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/cgi-bin/YaBB.pl General Category >> Technical Documents/Reference >> Fork & Shock Improvements for Café Conversions /cgi-bin/YaBB.pl?num=1421689358 Message started by Gary_in_NJ on 01/19/15 at 09:42:38 |
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Title: Fork & Shock Improvements for Café Conversions Post by Gary_in_NJ on 01/19/15 at 09:42:38 The RYCA guys got a lot right with the design of the CS-1. From its mechanical simplicity and purity to its aggressive looks; the CS-1 is a perfect homage to the classic single cylinder café racers of the 50’s & 60’s. However, if there is one aspect of the transformation from LS650 to CS-1 that can be improved – it is the front & rear suspension. RYCA’s solution of reducing the fork stroke to lower the front by 50mm has two significant drawbacks; 1) fork travel is reduced to just 75mm and in order to keep the forks from easily bottoming, 2) the fork springs are highly preloaded leaving little in the way of suspension compliance. This approach detracts from an otherwise elegant design. I wanted to build a RYCA CS-1, but if I was going to commit the time and money to build a café racer I wanted to ensure that the front suspension was appropriate for a “sporting” street bike. In making my CS-1 I have developed a solution for the forks that will: 1. Retain the full 127mm of fork travel at the slider ( there is an additional 13mm at the top-out spring) 2. Improve compression, damping and rebound to be similar to a cartridge type fork 3. As a result of 1 & 2 above, significantly improve ride & handling 4. Maintain the cool stance (50mm fork drop) of the CS-1 while improving the aesthetics Here is a breakdown of my solution. Retain the Full 127mm of Fork Travel No doubt, one of the reasons the CS-1 looks so darn cool is because of the way Casey raised the rear of the bike via an 18” wheel and longer shocks and lowered the front end by reducing fork travel by 50mm and using an 18” front wheel. Not only does it look cool, but it effectively reduces the rake and trail allowing for quicker and lighter steering. While this approach works perfectly for form; the fork solution is not very functional. Reducing travel AND stiffing the forks via highly preloaded springs is the perfect recipe for an uncomfortable and non-compliant suspension. It’s like riding a jack-hammer. Besides, you never want to give up suspension travel. Given the limitations of the LS650 fixed position upper triple clamp, RYCA didn’t have much choice but to shorten the stroke of the forks. But there is a very simple solution to replace the stock upper triple clamp so the forks can be adjusted (raised) to attain the proper stance. I purchased a LS650 lower triple clamp from eBay for $25 and converted it into an upper clamp. The entire process is simple and takes less than an hour. If you can modify the LS650 frame for the CS-1 conversion, you can modify the lower triple clamp into an upper triple clamp. The lower triple clamp has the steering stem pressed into position. Using a cut-off wheel, band saw or saws-all simply cut the stem flush with the top of the clamp. From there you will need to drill-out the center hole from 0.8125” to 0.8750” (a Unibit in a drill press works great). You should also cut/grind off the steering stop blocks and polish/blend the surface. In fact, cut the steering stops off first as it will give you a lot more room to maneuver around the steering stem when you cut it off. With this upper triple clamp in position, you can now slide the forks up in the triple clamps. You DON’T need to slide the forks up by 50mm, more on this later. If you are using RYCA’s speedo & tachometer brackets you will need to fabricate a means to mount the brackets to the lower part of the new upper triple clamp. You can make use of the unused headlight mounts in the upper triple clamp and fabricate a simple adaptor plate. Alternatively you can use the RYCA brackets as a template and fabricate a custom instrument bracket out of 0.125” aluminum. Just as I finished making my custom upper triple clamp RYCA introduced their own upper triple clamp that allows for adjustment of the forks as well; best of all – all of the work is done for you – at a cost of $250. It’s the old time-money trade. There is another difference that tilts towards using the modified triple clamp and that is the height/thickness of the T-Clamp at the pinch bolt. I will explain more on this later. Improved Damping I worked with Matt Wiley at Race Tech to develop a suspension solution for the LS650 forks. This solution will work for a café conversion and an unmodified LS650 (although the spring rates and valve setup will be different). Using a Race Tech Gold Valve Emulators (part number FEGV S3801) and linear-rate fork springs (part number FRSP S29380XX, XX is replaced by rate) you can significantly improve the damping (compression & rebound) of the conventional damping-rod forks used on the LS650. I’m not going to go into a lot of explanation on this as there is great documentation on the Race Tech website (racetech.com) as well as dozens of technical articles on the internet, but here is some info from Race Tech’s FAQ: “Damping rods while inexpensive to manufacture have major limitations. To create compression damping, oil is shoved through a hole or holes. Shoving oil through holes creates very little resistance to flow at low vertical wheel velocities as when hitting a dip or gully or applying the front brakes. This allows the forks to shoot through the travel fairly easily, diving or bottoming in these situations. On the other hand when the wheel hits something square edge, especially at speed, it needs a lot of oil to pass through the damping holes very quickly. Unfortunately the nature of shoving oil through holes is that as the wheel velocity increases the damping force increases with the square of the velocity. In other words if you double the velocity you get four times the force. This means the hole basically "hydraulic locks" resulting in a harsh spike. Damping rods give the worst of both worlds; they are both too mushy and too harsh at the same time. An Emulator is a valve that sits on top of the damping rod and is held in place with the main spring. To install them simply remove the damping rods and drill out the existing compression damping holes so they are so large they do not create any appreciable damping. Then during reassembly simply drop the Emulator on top of the damping rod. The Emulator creates the compression damping of a state-of-the-art cartridge fork. The ride is both firmer and plusher than the damping rod and is completely tuneable.” I’ve used Gold Valve Emulators many times in the past (street and dirt bikes) and have always gotten outstanding results. Race Tech has supplemental tuning instructions for vintage racing bikes and these instructions apply to café conversions as well. The instructions call for drilling additional small holes in the base of the emulator valve to improve low-speed flow. By following these instructions you will have dual-rate valving that provides low speed compression damping and high speed compression damping via the Emulator. My tuning details are at the end of this write-up. When using the Gold Valve Emulator you’ll need to use Rach Tech’s linear-rate springs. Progressive-rate fork springs just don’t work in a fork that has proper compression valving. The problem with progressive-rate springs is they attempt to do what proper valving actually does. Progressive-rate springs can have unpredictable or undesirable performance characteristics; too soft in the initial stroke (most notable with brake dive) and too stiff in the later portion of the stroke (resulting in a harsh ride). Preloading doesn’t solve the problem, it just transfers the problem to a different portion of the stroke or eliminates that usable portion of the spring…at which point you might as well be using a linear-rate spring. Using springs that are properly selected for the application and the rider’s weight (I used 0.70kg for my 170# weight) will allow you to set the correct suspension sag for the bike. For a street bike you should aim for 25% to 30% of your suspension travel for total sag. Since we have the full 127mm of travel available to us, this equates to 32mm to 38mm of sag. Ideally you should aim for 35mm of total sag with the rider on the bike. Remember I said that we don’t need to raise the forks in the triple clamp by 50mm? Here’s some guidance on how high to raise the forks and maintain the design stance of the RYCA conversion. The stock gap between the top of the fork slider and the bottom of the lower triple clamp is 187mm. If you were to add RYCA’s 50mm spacers (which we won’t be doing) that gap is reduced to 137mm. That’s our target gap/stance. RYCA’s fork solution has zero sag so that 137mm fully extended gap is present with or without a rider on the bike. One of the advantages of using the modified lower/upper triple clamp is that sits 13mm higher than the stock t-clamp at the top of the fork tube location - the stock clamp is 23mm where the new clamp is 36mm at the pinch bolt. Further, the OE forks were recessed 6mm from the top of the OE triple clamp. By raising the forks to be flush with the top of the modified triple clamp we’ve already made up 19mm of the needed 50mm, resulting in a 168mm gap fully extended. Of the 35mm of total sag we built into the suspension about 10-15mm of that will be present even without you on the bike (free sag), reducing the gap to 152mm-147mm. If you raise the forks (measured at the top of the tube, not the cap) by 16-21mm above the triple clamp you will have a gap in the desired range of 137mm allowing you to retain that proper RYCA stance. I say just set the fork tube raise at 25mm and be done with it. Important Set-Up Note: You can raise the forks as high as you want, but you should leave a minimum of 127mm (fully extended) between the top of the fork slider and the bottom of the lower T-Clamp. Otherwise your sliders may come in contact with the lower triple clamp during extreme braking. It’s up to you – you have about 10mm of available adjustability. The higher you raise the forks the faster the steering geometry. Since RYCA’s solution has zero sag, the rake is 29 degrees whether you’re off the bike or riding it. With 35mm of total rider sag deployed you will have about 28 degrees of rake when you are riding the bike. Using the available 10mm will get you in the range of 27 degrees of rake. Users of RYCA’s Upper Triple Clamp: At 23mm RYCA’s new T-Clamp is the same height as the stock unit. If you use this upper T-Clamp the forks will sit at a range of 29-34mm above the triple clamp when adjusted for a 137mm gap. This could look a bit odd, especially at the higher value. If I were to use the RYCA upper triple clamp I might consider using a 10-15mm travel spacer between the damping rod and the top-out spring. In order to keep the suspension compliant I would compensate for the travel spacer by reducing the preload spacer. Just follow the set-up instructions below and it should all work out. Looking Cool Here’s an opportunity to improve the aesthetics (form) and function of your CS-1. You can replace the stock LS650 38mm fork caps (you no longer need the flange on the OEM caps) with fixed or adjustable fork caps. Using adjustable fork caps will make the process of setting fork sag much easier and will give your forks a modern “race-bike” look. I found a few sources for 38mm adjustable fork caps on Amazon and eBay. I ordered a set for a Yamaha SRX400 from eBayer ericzzh715 for $35.99. A bonus advantage of replacement fork caps is that they will sit nearly flush with the top of the fork tube, versus the OEM caps that sit 7mm above the top of the fork tube. That’s an additional 7mm that the forks won’t protrude above the T-Clamp. Since you don’t have that unneeded flange on the cap you can remove a fork tube without disassembling the triple clamps and clip-ons. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 01/19/15 at 09:43:13 Finally, to further improve handling I’m using the fork brace offered by RYCA to reduce fork flex. This too looks cool and, more importantly, reduces fork flex during cornering and braking. The brace makes the front end of the bike more predictable and reduces the potential of tire cupping and irregular wear. My total investment for the above is about $500; $25 for the Triple Clamp, $36 for the Fork Caps, $110 for the Gold Valve Emulators, $125 for the springs and $190 for the fork brace (price the Race Tech components on Amazon to get the best prices). With all of the above changes you will have a bike that rides and handles as good as it looks – and a much better ownership experience. You’ll love riding your CS-1. Modification & Tuning Details • Drill out existing damping rod compression holes to 1/4” and add additional holes for a total of 6. There should be a pair of holes opposite from one another (180 degree spacing) and a single hole opposite of another single hole (also 180 degree spacing) for a 2-1-2-1 pattern at 90 degree intervals. The single holes can be drilled out to 5/16”. • Drill out the dimples on the base (under the spring) of the GV Emulator so you have a total of 4 holes. This will improve the low-speed compression damping. • On the Emulator use the 40# (Blue) spring at an initial setting of 2.5 turns. Adjust as needed in 1/2 turn increments to obtain the desired compression damping. If you need to go below 2 turns, replace the blue spring with the 26# Silver Spring and start at 3.5 turns. • Use 15w fork oil at a height of 130mm (GV in, spring out, tube at bottom of stroke) • If using Adjustable Fork Caps, set all the way out (retracted). Cut preload spacers so the top of the stack is about 7mm below the top of the fully extended fork tube. This will provide a baseline preload of 15mm (the cap is 22mm fully retracted). Use this setting whether you are using a modified upper triple clamp or a RYCA upper triple clamp with a travel spacer. • Set the fork height at 16-21mm from the triple clamp to the top of the fork tube (or 137mm from bottom of lower T-Clamp to top of Slider). If using RYCA’s upper triple clamp a 137mm gap will result in a fork height of 29-34mm above the t-clamp – consider the use a travel spacer between the top-out spring and damping rod. • Target Sag; bike only 10-15mm; with rider 35mm • Rule of Thumb: The first 1/3 of fork travel is controlled by the spring and is used mostly for sag. The next 1/3 of travel is controlled mostly by the GV Emulator. The final 1/3 of travel is affected by oil height. If initial compression is too soft (fork travel is too fast), increase the spring tension (tighten) of the GV Emulator in 1/2-turn increments. Do the opposite if it’s too stiff or slow. If the final 1/3 of travel is too soft and bottoms, add oil in 10cc increments. Do the opposite if you can’t use 85-90% of all fork travel. If you need to slow rebound switch to a heavier weight oil (by the same manufacturer as there is no consistency between manufacturers). Do the opposite to quicken rebound. • If you cannot achieve the desired free sag setting (10-15mm) with the range available of the adjustable fork caps, it is an indication that the spring rate is incorrect. I know this seems counterintuitive, but if there is too much sag - the spring rate is too high; too little sag indicates that the spring rate is too light. A great resource for setting sag can be found at http://www.ntnoa.org/suspension_preload.htm As you can see, you now have all of the same adjustments as modern cartridge forks (preload, high-speed compression damping, low-speed compression damping and rebound). Since you don’t have “clickers” you’ll have to somewhat disassemble the forks to make adjustments. Oil level changes are easiest; simply remove the fork cap (one at a time so the bike doesn’t squat down) and add/remove a measured amount of oil. To make changes to the Emulator, remove the cap, spacer, washers and slowly remove the spring with a turning motion so the oil says in the fork. You can then remove the Emulator with a magnetic parts chaser. For a whole-sale change in the fork oil you’ll need to remove the fork, disassemble, drain and reassemble using your original technique and procedures. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 01/20/15 at 05:21:30 This is definitely a thorough and well planned change, and I agree that keeping the available fork travel is a big improvement over installing spacers that lower the front end....reduce travel......and make for an excessive amount of pre-load. I might even be intrigued enough to try these emulators and springs in my bike soon. And while the theory of all this seems sound - at this point this is untested, as it does not appear your bike has been ridden yet. Looking forward to the completion of your bike...and a Build Thread in the Rubber Side Down section. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 01/20/15 at 14:41:28 My bike is being assembled and I wont get a chance to dial in the suspension until the salt and sand are off the road. However, with that said I have a lot of experience with suspension set up and I'm certain that I'm quite close with my baseline. Matt and I discussed in detail the set up for the CS-1. The only real unknown is my baseline spring rate. I chose 0.70kg and 0.75kg was a possibility as well. My experience tells me to err on the lighter side for a street bike. If I need to go heavier, Race Tech will provide a swap out. I have photos to post of the damping rod and emulator modifications. I'm on the road this week and won't have access to post them until the weekend. I'll also provide a measurement for the spacer. I was able to reuse the stock spacer and I think I cut it down by about 10mm. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Flint on 01/20/15 at 19:36:15 That was an excelent post Gary and I read it several times. I bought a new S40 and have read many reports of people grinding footpegs and mufflers while cornering. Not something I wanted to hear of course. Raising the back seems simple enough by changing shocks but the front end seemed a bit problematic. After reading your report I feel a bit better. Thanks. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 01/23/15 at 08:21:31 The RYCA Cafe' (and most clones of their design)will have a similar weight without the rider - for me the big difference would be the extra couple of gallons that my fuel tank can hold. What is the best way to determine what rate of springs to use in the forks? Should I weigh the front of my bike with and without the rider? Should I measure my current pre-load and sag with the stock springs? Currently I do use a lot of my available travel....I have installed 0.5" spacers to lower the front end, and I have dropped the tubes in my forks about 1.5". |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 01/23/15 at 09:28:10 RaceTech has a spring rate calculators on their webisite (Search on the Menu Bar then Spring Rate). The calculator for the LS-650 should not be used for café conversions as our bikes weigh about 60 pounds less and our weight distribution is vastly different front-to-rear. I used the calculator for a Yamaha SR500 as it approximates our bikes fairly closely and it’s also a bike that typically gets modified into a café racer. When using the calculator simply click the “Street” riding type and enter your weight. You can update the bike weight for your specific bike. This is “fairly accurate” and should get you in the ball park for spring weight. Always round up to the nearest suggested spring value. The next highest value can also be used due to our forward weight bias with a rider on board. For example; the calculator suggests a rate of 0.688kg for a 170 pound rider on a 310 pound bike riding on the street. That rate doesn’t exist, so I rounded up to 0.70kg. I could also use 0.75kg, but my experience tells me that I’ll be happier with the lighter spring – it’s slightly more plush – and I can achieve the correct free and total sag. If you are “Joe Street Racer” (no judging – I use to be him and enjoyed it) I’d suggest going for the heavier spring. If you have two bathroom scales you can get the weight of your bike (full fuel) by placing a scale under each wheel. I’d be interested in knowing the weight distribution. You should be using “a lot” of your available fork travel – about 90% under severe braking. If you are using a lot during normal riding it’s an indication that the oil level is too low or the spring rate is too light. A good way to determine fork travel usage is to put a zip tie on your forks. It shouldn’t be so tight that it’s hard to move, nor too loose that it won’t hold its position. Go out for a “normal” ride and see where the spacer is sitting. If you have 4-1/2 inches of travel (5 inches less your ½ inch travel spacer), I’d expect to see the zip-tie around 2-1/4 to 2-1/2 inches from the wiper. More usage would indicate a spring rate that is too light. Then go out again but this time include a few “emergency stops”. In this case the zip-tie should be around 4 inches. If it’s more you need to add fork oil. All of this is assuming that your free sag and total sag are correct. If these don’t meet the guidelines above (10-15mm free and 35mm total) then these calculations won’t tell you very much. Since you have raised the tubes in the clamps by 1-1/2 inch, I’m assuming that you don’t have much sag in the system. Also, the stock springs are progressive so they are both too light and too heavy. The only use I had for the OEM springs was to determine the correct length spring. Race Tech loves working with racers and tinkerers and will work with you to get your suspension correct. If you order an Emulator and Springs and can’t get the sag correct, they will use your measurements to determine the correct spring rate and swap-out the incorrect springs for the correct ones. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 01/23/15 at 10:31:51 Thanks - I will weigh my bike and let you know. Instead of having 2 scales - you can get by with a single scale as long as you have a block the same height of the scale under the other wheel to keep the bike level. It is really handy for me that our home scale is the same height as a 2x4 laid on it' side. (I have to be sure to get the tire tracks off the scale when I return it to the bathroom....so my wife doesn't know what I was doing). And for that 7mm gap at the top of the fork tubes where the cap doesn't cover - I found an O-ring that fit in that groove perfectly and it looks like it belongs there. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 01/23/15 at 10:42:27 Yes, one scale with a wood block will work just fine. There is an o-ring that is attached to the fork cap. That should be inside the groove that sits just above the threads on the cap. It should look like this: |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:21:59 Here is a better photo of the difference in the caps. BTW, the flange on the OE is not 7mm, it's 12mm. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:32:18 Here are some photos of the fork modification and assembly. The first set of photos show the modifications to the base of the Gold Valve Emulator. This photo shows the spring base in place in the Emulator valve. You can see there are two holes and two dimples. Next to the Emulator is a base plate where the dimples have been drilled out to 7/64". |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:33:57 This is an action shot of me drilling the dimples out. Make small cuts so it doesn't spin out of your fingers. Use cutting fluid. I use BoeLube paste as it makes drill bits cut like a hot knife through butter. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:34:41 BoeLube, invented by Boeing. Best lube available. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:36:22 When you reassemble the Emulator, replace the yellow spring with the blue spring. If testing shows that the silver spring works best, I'll update the instructions. When you reinstall the spring you'll be setting your initial valve tension. Hand tighten the post into the valve base so the spring doesn't move on the post. Add the nut at the bottom so it just contacts the valve, then make your initial setting by rotating the hex fitting on the post by 2-1/2 turns (or hold the post and tighten the nut by 2-1/2 turns). |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:42:12 Here is a 0.70kg fork spring shown next to the OE progressive rate spring. The OE springs are 405mm long and the RT springs are 375mm. This difference is accounted for with the height of the Emulator valve (16mm), the longer depth of the fork cap (12-25mm) and the spacers. Also, the OE springs are 31.8mm in diameter and the RT springs are 29mm in diameter. Race Tech has springs that are 31.8mm wide, but the rates are too high for my weight. If you weigh over 210 pounds, consider FRSP S3234 springs. They are 32.7mm in diameter and start at a rate of 0.80kg. They are 340mm long, which means they are lighter. If these came in 0.70 or 0.75kg, I would have gone with that part number. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:44:03 Here is a photo of the spacing of the Damping Rod compression holes. On the sides where there are two holes there should be a space of 20mm. As I mentioned, drill these out to 1/4" for the pair and 5/16" for the singles. There is no harm done if you just make them all 5/16". This damping rod is right on the line where you use all 1/4" holes or all 5/16". That's why I used two different sizes on mine. If I were to do it again, I'd just go 5/16" for all six holes. What is important is that these OE holes be made larger so they don't restrict oil flow for compression damping. That is now handled by the Gold Valve Emulator. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:47:46 Drilling tips: Go in steps (1/8" then 3/16" then final size) and make small cuts, backing off often to allow the bit to clear. Use cutting fluid (or Boelube) too. After the rod is drilled, you have to debur the outside and inside surfaces. The photo shows me using a speed deburring tool, but a larger drill bit for the outside and a rat-tail file for the inside can be used. Use brake cleaner and compressed air to get the small bits of metal out of the rod. You don't want metal floating in your forks, otherwise say goodbye to your fork seals and the screen in the Emulator. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:50:23 If you use the adjustable for caps you'll want to use the OE washer between the PVC spacer and the cap. The ID hole of the RT washers are too small and will come into contact with the clip at the bottom of the cap. The RT washer can be used between the top of the spring and the PVC spacer. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 01/24/15 at 14:57:20 Here is a photo of everything ready to go. Well almost. The photo shows two RT washers (see post above) and the OE spacer. I did use the OE spacer but only because I had 32mm OD washers from a prior project. The OE spacer will slide over the RT washer and spring (not if you use the FRSP S3243 spring). No problem, Race Tech provides a length of PVC that is used to make two spacers. I think my spacer length is around 120mm. Next time I have the forks apart I'll take a measurement. The measurement is only valid for those using the adjustable fork caps. If you are using the OE or fixed 38mm fork caps your spacer will be longer by about 10-15mm. If you use the FRSP 3234 springs your spacer will be longer by 35mm. What is important is that your baseline preload should be 15mm. You will make adjustments from there when you set the sag. That's why the adjustable caps are so nice, you don't need to open the forks and add washers or a longer spacer...just turn a wrench. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Levi on 02/11/15 at 22:57:40 Hey Gary so how did the conversion turn out? I'm wanting to start the process on this! :D |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 02/12/15 at 05:39:01 666F7C636B6D0A0 wrote:
I don't know yet. Everything is together and ready to go, but I've got icy and salt/sand covered roads in NJ. Not the best or safest conditions for testing. I'm hoping that I can get it out on the road in 4 to 6 weeks. All of my static measurements check out so I'm sure I'm down to just a few tweaks - if any. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by LANCER on 02/16/15 at 15:50:01 Somebody needs to turn up the sun to melt the roads so we can hear the results. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by phatts27 on 02/17/15 at 05:47:08 **also in nj. **also thinks the snow should melt |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by RB on 03/11/15 at 16:46:48 Hey Gary Just stating the obvious, for all of anxious short travel fork owners, the weather in Jersey looks warm enough for a test ride......kidding (sorta). Looking forward to hearing how this mod worked for you. Thanks for posting this one. Cheers RB |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Jeff71 on 03/11/15 at 20:19:42 Did you guys see what Ryca just came out with? :) https://www.youtube.com/watch?v=3sqEtQ8x9-A Jeff |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/12/15 at 05:57:16 I'm looking at the weather closely too. There is a lot of sand on the roads right now...and there is a stream running across my driveway (it's an actual stream that appears during heavy storm surges) due to the rapid snow melt. Right now the bike is in pieces as I go through final assembly - torquing and applying Loctite to all fasteners - following initial assembly. I also have some SWEET custom parts inbound. There are some very talented people on these forums and I have taken advantage of their designs, ingenuity - and when possible - their labor. I just finished making some brackets out of 0.125" 2024 for the rear brake light switch and ignition key that I had prototyped in 0.032" 2024. So there is some work to be done this weekend. I'm feeling good about completing the final assembly Saturday and then adding the two inbound parts when they arrive next week. I don't need the custom parts for a test ride. We're supposed to get a good driving rain on Saturday. I'm hoping that clears most of the sand off the roads and completes the snow melt. My driveway is over 1/4 mile long, as soon as the stream clears I can at least get it going under power. I'll conduct my low-speed brake tests on the driveway and evaluate/measure the fork dive. Regarding the RYCA upper triple clamp, I mentioned in my first post that it is available. I had sent a photo of my custom lower/upper to Ryan and he was like "sweet dude...I'll have one on the website in a week". If I had known I may have saved myself a lot of work. Even so, I'm very happy to have found my own solution at a cost just 1/10 of RYCA's upper. That, and my upper sits 13mm higher at the pinch bolt then the RYCA unit which makes the perceived protrusion of the fork raise seem smaller. My forks sit 25mm above my clamp; had I used RYCA's custom clamp they'd sit 38mm higher. To my eyes that would look very strange, resulting in using a 13mm spacer in the forks. So my upper allows full travel of the forks. In short...I like mine better ;) |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by RB on 03/12/15 at 17:19:17 Good luck with the bike work and the weather. I've got my tank and bodywork at Connery's Custom Paints getting painted a Mercedes AMG matte grey. It'll be more than a few more weeks before I'm ready to ride. But like most, I'm looking forward to getting back on the road, Feb was cold!! |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by verslagen1 on 03/13/15 at 09:15:37 [split] [splithere] (http://suzukisavage.com/cgi-bin/YaBB.pl?num=1426262416)[splithere_end] |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 03/15/15 at 15:14:07 Well today was the day when my bike migrated from the building stage to the riding stage. I updated my Builders Log on the short ride, but I wanted to provide initial feedback on the suspension. With the bike on the ground and with my son’s help I was able to dial in the sag on the suspension. My forks are preloaded at 15mm, and 0mm at the caps. I’m using adjustable fork caps so adjustment is as simple as turning a wrench. The caps allow up to 20mm of additional preload. The goal for properly set-up forks is 10-15mm of static sag (just the weight of the bike) and 35mm of total sag (me on the bike with gear on and the tank filled). My initial static sag was 19mm and my total sag was 38mm. I also measured the sag at the rear at 10mm static and 30mm total. This is with the preload adjustors set at 4 clicks. The method for measuring the rear allowed for some variability so I don't have high confidence in those figures, but they are in a proper range. I'll get better data in the coming days. I dialed in an additional 5mm in the front and achieved 11mm static and 33mm total. I'm gonna leave everything where it is for now until I have a few hundred miles on the bike. My ride was short (due to a fuel issue) and not very taxing on the suspension. However I can already tell that the suspension is dialed in nicely. A few slow speed brake tests show that I'm using a fair part of the stroke. Higher speed testing will reveal the exact amount, but under heavy braking it should be near 90% and under normal riding in the range of 50-60%. If you've been waiting to pull the trigger...go ahead. It all works as expected and all signs indicate that this is a sweet riding bike. No RYCA owner has ever uttered those words before. By the way, this was the first opportunity I had to sit on the bike while not on the building stand. It's a tiny little thing. And it’s not the torture rack I expected. I wouldn’t call it comfortable, but I’d say it’s an aggressive riding position for a sporting street bike. It’s stretched out well, and that takes a lot of weight off of the wrists. With some airflow on my chest I’d imagine that this might be an OK riding position. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/16/15 at 04:40:21 What is your weight Gary???? sounds very dialed in already. Nice job! .....when do you want me to send you my forks? ;) |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/16/15 at 05:23:15 I'm 170 pounds. Use the calculator here to determine the correct rate springs --> http://racetech.com/ChooseVehicle.aspx DO NOT use the calculator for the LS-650, it's not correct for cafe conversions. Rather, choose the radio button for "Street" then Yamaha/ SRX600/1895-89. Be sure to update the weight of the bike with the weight of your bike. 310 to 320 pounds should be correct. You are only going to use the rate information for choosing the spring (i.e 0.80Kg). The Spring part number is FRSP S29380XX, XX is replaced by rate (in keeping with the prior example FRSP S2938080). The GVE part number is FEGV S3801. It should come with a Blue and Yellow Spring. I'd be happy to update your forks. You're local (well, in state) so no need to ship. You can bring 'em to me. But it's a fairly simple job. It's one of those things that once you start you see how easy it is. The hardest part is deburring the inside holes that are drilled in the damping rod. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by haylo on 03/16/15 at 15:13:56 Gary...Thanks again for all your help! I'm thinking of mounting my clip-ons above the top clamp for a tad better ride position. Any thoughts on this? Haylo |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/17/15 at 05:16:57 3D342C393A550 wrote:
If you are using RYCA's top triple clamp I think you will be fine. If you are using a modified lower t-clamp I think that there a possibility that the top of the fork sliders will make contact with the bottom of the lower triple clamp. Here's how I get there... I looked at this quickly a few weeks ago, and if my memory is correct the mount for the clip-ons is 40mm (1-5/8"). My forks are raised 25mm above the triple clamp and I have 13mm reserve between the the top of the stroke and the bottom of the t-clamp. If I were to raise the forks up an additional 15mm (5/8") I'd be into my saftey zone by 2mm. However, my triple clamp it 13mm taller at the pinch bolts then the RYCA unit. If you use the RYCA upper you'll have plenty of margin at the top of the stroke. If you use a modified lower you'll be 2mm into the margin. The likelihood of bottoming out is near nil...but it does exist under the most extreme conditions. All of my measurements are based on using flush fork caps like my adjustable caps. I believe there is 7mm of additional margin on the stock caps. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/17/15 at 05:27:41 I got my bike all sorted out last night, so I hit the road for a good test ride. The bike communicates very well. There wasn't a moment where I didn't know exactly what the front tire was doing. This gives me great confidence in the bike. Not surprisingly, the feedback from the front tire/forks feels a lot like the other bikes I've modified with RaceTech Emulators, especially my SV650S. So right off the bat the CS-1 feels very familiar. The spring rate I've chosen seems to be spot on. I was able to get the right sag figures (11mm of static sag and 33mm of total sag) and the ride is controlled and comfortable with no undue oscillations. My initial setting for the GVE seems to be good so far. Under normal riding and braking I used 70mm of fork travel - that's 55% of available travel - right in the sweet spot. I still have to take measurements after extreme braking, but I'm not sure I can achieve those conditions with the OEM brakes. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/17/15 at 06:07:28 1) What did this mod due to the final front ride height? 2) Can you take a measurement of rake and trail with rider? That would be a good piece of info to have. 3) Ultimately; what was the total cost of the upgraded forks? 4) Clarification: will the stock ryca clip ons work with the stock upper clamp ON TOP of the upper tree? I already have a Tkat brace. Looking also for slightly higher bars. Possible swan necks or mounting the clip ons above the bar. Gary: PM sent |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/17/15 at 06:21:33 1) The ride height is almost exactly the same as RYCA's 2" drop. My bike sits a about 10mm lower then the kit height without a rider, and over 25mm lower with a rider on board, so the rake is less then RYCA's. How much I don't know yet. 2) I will take measurements. 3) As indicated in my second post in the thread; "My total investment for the above is about $500; $25 for the Triple Clamp, $36 for the Fork Caps, $110 for the Gold Valve Emulators, $125 for the springs and $190 for the fork brace" 4) With this mod you can mount the clip-ons above the triple clamp. See post #32 above. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 03/17/15 at 10:40:22 2D2937303968675E0 wrote:
I believe he answer is no. The stock upper clamp on the Savage does not have a clamp, it has a lip that prevent the fork tube from extending up through the top yoke...the tube slides up into the yoke and hits the bottom side of the lip, and the cap screws on and clamps the lip between the tube and top nut. You cannot get the tube to extend up above the stock upper clamp. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/17/15 at 10:46:07 Yeah, perhaps I wasn't clear enough, you will need to replace the upper triple clamp. You can make your own or purchase one from RYCA. You might want to contact Gerry as he can make one as well. His is cut-out and has a real custom look. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by haylo on 03/18/15 at 16:32:22 During my assembly of the modified upper clamp (described by Gary), I found the RYCA clip-ons just a tad too "thick". Too much tube would have to be exposed for this mod. It's close though. Another brand clip-on perhaps? haylo |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/18/15 at 17:20:40 I just went out to the garage and took a measurement, the clip-on mounts are in fact 1-5/8" high. Do you still have the RYCA 2" spacers in place? If so, you are correct it will never work. You'll have to remove the spacers. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by haylo on 03/19/15 at 09:30:34 Gary..No, the spacers are out. That was the primary reason for making this mod..to regain that 2" of travel. With the RYCA clip-on installed above the top clamp the seal does contact the lower clamp (with no spring installed). I assume this will not be a problem once all the internals and fluid are in and with caps on. Certainly would like to try the higher bar position. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/19/15 at 09:42:38 Got ya. Yes, without any resistance from the spring and oil it will make contact - but it should only be a few millimeters. You can confirm this by having the lower "just" make contact with the lower triple clamp and then measure how much fork is protruding above the upper triple clamp. It should be about 1-1/2". |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by haylo on 03/19/15 at 10:46:04 Gary..We're on the same page regarding measurements! So in your opinion that additional 1/8" exposure needed for the clip-on should not be a problem once all internals, fluid and cap are installed? Thanks a ton for helping with this. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/19/15 at 10:55:11 If you use that last 1/8" of travel, you've got bigger problems then the 1/8" of travel - you probably just hit a 12" deep pot hole and now have a oval front wheel. If you want to play it safe, you can add a 1/4" spacer (cut from the 2" spacer) between the damping rod and top-out spring. But in reality, if you get your suspension dialed in right you wont be using the last 10 to 15% of fork travel. That's 13 to 19mm. I'm thinking you'll be good to go. I can't wait to see a photo of the clip-ons mounted above the t-clamp. I think there's a lot of people interested in that result. What I'm mostly interested in hearing is a ride report. I'd like to hear the "night-and-day" difference in ride and handling. I can only imagine how uncomfortable the 2-inch drop is to ride. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/30/15 at 06:24:45 I'm thinking that the oil height in the forks could be 140mm rather than my initial setting of 130mm (less oil). I'll know for sure after doing some heavy braking tests in the coming days, but as of now I'm using about 60% of available travel and I've yet to go beyond that mark. However with that said, I haven't hit any big bumps nor have I been able to make a real short stop. After the brake tests if I get into the 85% range I'll leave it be. To reduce the oil height I just need to remove the caps (one at a time) and insert a hose into the forks and attach it to a syringe to extract a measured amount of oil. A 5 minute job. Knowing that the inside diameter of our forks is 33mm and we want to reduce the height by 10mm, that measured amount of oil is 8.55ml (0.289oz) for every 10mm [Volume = Pi x R^2 x Length]. My spring rate and GVE settings are spot on and should serve as a good reference point for anyone doing the fork conversion. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/30/15 at 09:24:55 Nice report Gary. BTW: springs and GVEs arrived in the mail the other day. School is off this week, but I may have some day time to get in a tinker a bit, and maybe removed the forks. The rear shocks are probably noticeably stiffer, only because you know have a compliant working, properly sprung front fork set. What is your preload on the rear? |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 08:28:55 STOCK UPPER FORK TREE MOD. - Observation - comment - caution! When doing the "famous Gary from NJ" fork mod., my upper triple clamp will be a modified stock lower. I'm in the process of doing that right now. Again, this is for a modified STOCK LOWER that to become an upper. This is necesary since you need to have pinch bolts, as the new tube position will be through the upper clamp (see Garys' picts). RYCA now offers a upper clamp too. Gerry made an entirely new upper....way cool looking piece! Anyway - back to the mod I'm doing on the donor stock lower: 1) Stem removed, cut flush with the top surface of the clamp. check 2) Steering stops removed and smoothed. check 3) Stem hole opened to .875, that is SLIGHTLY larger than the stock hole in the upper clamp. I'm fine with that as it will give a small amount of room for misalignment. The upper bearing will actually hold the stem in alignment with the frame along with the lower bearing - as by design. The upper tree will then be sandwiched between the crown nut and the bearing retaining nut. CHANGE: I check the thickness of both trees - they are the same at ~ 26.7mm. I noticed that the stock tree upper, has a spot face relief on the underside where the stem comes through of a depth of 4.86mm. The purpose of that spot face is to allow the larger OD threads (where the upper stem bearing nut engages) to enter into the underside of the upper tree. I checked my new tree then and added a spot relief with a 1" drill. I had to drill a little deeper to accomodate the angled cutting face of the drill. I went down ~5 mm. A little deeper is not a problem, too shallow is. WITH the spot relief, the top chrome nut will now tighten the upper tree down directly onto the top face of the bearing nut. WITHOUT the spot relief, the top chrome nut MAY (will in my case)tighten the upper tree down onto the ramped transistion area or even the top threads of the larger OD threaded portion of the stem where the bearing nut engages. If so, the upper tree will not bear up against the retaining nut. This could result in the top threads being damaged; the bearing nut backing off - causing loss of bearing preload and loose head bearings. FIX: spot relief - takes more time and effort...but easy to do initally. If the mod is already done? Machine a ~1/8" (3mm) flat washer that goes between the bearing retainer nut and upper tree. Reminder of what the stem dimensions are (sorry..no camera today to take a pict.) From the top down with a vernier on the ODs.: Chrome crown nut 21.75 mm dia. - 12.5 mm height Smooth section for upper tree: 22 mm - 22 mm height Small transistion: 2mm in height Bearing Ret. Nut: 24.75 mm dia. - 15mm height As you can see by the dimensions listed, the smooth area for the top tree is smaller than the top tree. Gary ; comments? You may have added the relief - I'm not sure, but its something to look for.... Mike One HISTORICAL note: "old" style bikes used to have a pinch bolt at the crown nut. BUT, those crown nuts had sleeves that went through the upper and locked against the bearing retaining nut. The savage doesn't have this design. The upper tree just slides over the stem and as the crown nut is tightened, it loads the upper tree down onto the bearing retainer nut, locking it into position. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/31/15 at 09:16:19 Photo's will go a long way here. This is a photo of my initial fit. http://i834.photobucket.com/albums/zz263/GaryCorde/Mobile%20Uploads/IMG_1704_zpsbe911272.jpg I did not add any relief, nor do I think it is necessary. The steering stem is held in place by the steering stem nut. The upper triple clamp is now held in place via the pinch bolts (primary) at the forks and the steering stem cap nut (secondary). In fact, the stem and cap nut only serve as a pivot location in this configuration. This is different then the OE method where the fork-caps and upper triple clamp are working as a system. The new method is how the vast majority of modern bikes are designed and assembled. In the new configuration, the upper triple clamp does not provide any clamping force to the steering stem, however it does severe as a "jam-nut", keeping the stem nut from backing off from it set location/torque. Even without the 4.86mm relief at the bottom of the upper triple clamp the steering stem cap nut has more than adequate engagement for the cap nut. If there is any concern, simply leave the washer out. I used the washer and I'm very comfortable with the engagement. I don't think that the 4.86mm will effect anything. If you have the means to bore the lower side of the upper triple clamp, by all means do - but it is not a safety concern. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 09:33:53 Hi Gary. I'm 100% in agreement, that is set up is better than original. Maybe I wasn't clear in my explanation: The bottom relief will allow the taper / larger OD section of the stem to intrude into the top tree "as much as needed". Its not a matter of the top crown nut having a reduced thead count. there are plenty of threads available. The issue is on the bottom of the tree. The safety issue is IF: the top tree contacts the little "ramp" section or the bearing retainer threads BEFORE it contacts the bearing retaining nut. As you said; the top tree is the effectively the "jamb nut" for the upper retaining bearing nut. I'll have to post a pict..... |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 03/31/15 at 09:39:52 I get what you are saying. I don't have a 1" drill bit that can cut a counter bore. 4.86mm is essentially 3/16" If there is a gap (I have to check) this could be closed with a 3/16" washer. I believe that the fork spacer washers (how convenient) could be repurposed for this use. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 11:29:02 here are some picts. I used a stem and the OEM top. Picts 1 and 2 are the top and bottom WITH the bottom relief in place, as stock. You can see that the flat washer under the crown nut is needed due to running out of useable threads! Relief covers some of the bearing retainer nut threads. Picts 3 and 4, I flipped to top tree to simulate a "no relief" condition. You can see the "ramp" section prevents the top clamp from going any lower, which many result in the top clamp not jambing the bearing retaining nut. My camera was dropped, so the picts with the shaded left edge distort the image.... :D nothing is bent! lol I've got a 1" drill you can use... OR come on down with the tree and we'll drill it real quick.... OR: yes, use a 3mm washer / spacer above the bearing retainer nut / below the upper tree to close the gap. The only down side is you'll have less threads at the crown nut. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 11:29:19 . |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 11:29:42 . |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 11:30:01 . |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 03/31/15 at 15:25:50 Here are some photos of the actual assembly. I don't think it's worth shimming. http://i834.photobucket.com/albums/zz263/GaryCorde/Mobile%20Uploads/IMG_1845_zps1c59b34c.jpg http://i834.photobucket.com/albums/zz263/GaryCorde/Mobile%20Uploads/IMG_1844_zpse8f6c27a.jpg |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 15:34:22 1) Can you get a feeler gauge in there? if so, what's the value? If its touching...you're fine. 2) If you tap the notch on the bearing retainer, does it move (unload) easily? If you can unscrew the bearing retainer slightly - check for wiggle between the stem and steering head. Optimum is none. But I've also been on ball bearing bikes that had a very slight amount, and it made no difference to me. Your call though, whatever your comfortable with. If was just easier for me to add the relief with everything apart. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 03/31/15 at 16:08:09 The adjusting nut is torqued to spec, so there is no movement at the nut nor is there any wiggle. The distance between the bottom of the upper triple clamp and the top of the adjusting nut is 0.039" or 5/128 of an inch. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 03/31/15 at 17:07:08 Hey Gary. That is a small gap for sure. But a gap is a gap. The nut is torqued, but essentially the locking feature (the top tree) isn't there to keep it there. If you're going to ride as is, maybe just put a witness paint mark between the headstock and bearing retainer nut to be able to do a visual check to see if it moves. Question 1: was your final fork spacer length 120mm??????? ( will check that it is 7mm down from the top of the tube upon initial set up as you suggest). Question 2: in your set up, you mention: Use 15w fork oil at a height of 130mm (GV in, spring out, tube at bottom of stroke) 130mm measured from where to where? or is there an ounce or cc measurement? Thanks for all your help..... |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary in NJ on 03/31/15 at 18:55:05 696D73747D2C231A0 wrote:
[/i] Answer 1: I think that the final spacer was 127mm. My length isn't important. You just need to cut the spacer so you are 7mm below the top of the fork tube (fully extended). Answer 2: The 130mm is measured with the GVE installed, the spring out, and the fork tube at the bottom of its stroke. It's a distance (in mm), not a volume or liquid measurement. I find it helpful to use a syringe with a piece of hose attached so the total length from the bottom side of the top handle to the bottom of the hose is 130mm. http://i834.photobucket.com/albums/zz263/GaryCorde/Mobile%20Uploads/IMG_1743_zps408aa657.jpg Just rest the syringe on the top of the fork tube and pull up on the plunger until you're sucking air. As I mentioned a few posts ago, 140mm might be a better value. I don't think I'm getting 90% use of my stroke and the extra 10mm will make a big difference. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 04/01/15 at 05:54:22 I gave this some thought on the way to work this morning. I believe that if the stem adjusting nut were to back out until it made contact with the upper triple clamp, it could only travel 20-30 degrees of rotation before making contact with the upper triple clamp, and it would still be well within the torque spec of 22-29 ft-lbs as I'm at the higher value. In fact, the recommended procedure is to torque to this value and then back-off the nut 1/4 to 1/2 turn. I believe I'm somewhere between that value. I can safely back it off until it makes contact with the upper triple clamp. While I think it would be "nice" to have the recess, it's not at all necessary. If a future builder has the capability - great. If not, don't worry. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by haylo on 04/01/15 at 06:44:37 What is the top tree bottoming out on if not the lip of the bearing nut? The RaceTech info specified 150mm as the measurement of the oil. That seemed a tad much but turned out to be about the same as the stock cc recommendation. Isn't the emulator taking up space? Gary...your 120mm seems more in line. How did you come up with that amount? I used a "plastic" toilet riser...measured down from the moulded washer 150mm and drilled a hole. Over filled the tubes then suctioned till drawing air. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 04/01/15 at 06:52:58 767F6772711E0 wrote:
Matt Wiley from RaceTech suggested 130 to 140mm. I thought "better to be too stiff at the bottom of the stroke than too soft" so I chose to use the 130 (more fluid) figure. It just takes a few minutes to make this adjustment and I will probably make this adjustment after the weekend. Whether 150mm or 120mm, it will always be close to the OE fluid volume of 15oz as every 10mm of height is only about 0.3 oz - so that 30mm swing is just under an ounce of fluid. But a 10mm height change makes a B I G difference at the bottom of the stroke. The OEM spec is 75mm. That's a lot of oil. They were trying to do all they could to stiffen the OE solution. Good solution on the oil extraction tool. Got a photo? |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by haylo on 04/01/15 at 08:17:26 You're right! I was thinking backwards and probably confused a few with my post. The 150mm is in fact a lesser amount. My computer is soooo old...Flicker or Photobucket just won't accept me! I'd like to send pics of the clip-ons mounted "above" also. Not sure I like the look....but can live with it if easier on the wrists. That is my only discomfort when riding the RYCA. I'm not going to worry about the relief issue with the top clamp but if I go back to the lower mount of the clip-ons...I'll probably look into it while disassembled. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 04/01/15 at 10:23:40 Havlo; its a very easy thing to remove the top clamp with modded lower as the top. crown nut, 2 pinch bolts.....Oh, yes...gauge cluster too. Its all going to depend on your tolerance stack in the build. Gary may be OK, but you might not be. OR....you might be better than Gary too! Gary: why a washer between the cap and spring? |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 04/01/15 at 11:33:41 3337292E277679400 wrote:
The spring does/will move around in the forks. The washer is a nice stable surface that will protect the hinge-pin that is used on the bottom of the adjustable cap. 3337292E277679400 wrote:
I did some digging last night. I have some fork spacer washers left over from other fork builds (FZ6 or SV650..can't remember) that are 35mm overall, 25mm at the center and 2mm in height. Perfect for gap filling. I'm sure RT would send them. [/quote][/i] |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 04/03/15 at 14:42:08 My son and I just spent some time dialing in the suspension setting. Here's where I'm at (and staying for the moment). I used the averaging method (without bounce and with bounce) to obtain these values. These numbers are with me in my riding gear with a full tank of fuel. Forks Free Sag (no rider) 15mm (7mm stiction) Total Sag (rider) 35mm (3mm stiction) Total Travel 75% at 140mm of gap Shocks (preload collar set on 4 of 5) Free Sag 10mm (5mm stiction) Total Sag 39mm (2mm stiction) Stiction is the delta between the bounce value and the no bounce. The stiction values are good. You want them below 10mm, the lower the better. These measurements were taken many times, and every time you get something a bit different. The numbers above are averages after my final adjustments. The rear shock numbers need further research. I know that RYCA lists the rear suspension travel as 2", but I'm thinking that is the shock travel, not the travel from the end of the swingarm. My measurements are from the axle nut to a spot that my son liked on the license plate. The delta between fully extended and the total sag figure is about 1.5". I hope I'm not using 75% of the shock travel just sitting on the bike. I have a feeling that the actual suspension travel at the end of the swingarm is closer to 3". Even so...that's 50%. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by swing69 on 04/06/15 at 11:12:23 Hi Gary. strange as it may seem, I came up with a 127 spacer as well! One spring was slightly longer than the other (4mm worth), but I made both spacers the same. I also replaced the adjustable disk on the fork cap PIN with a cotter pin, that way I could use the RT washer. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by singlesgoinsteady on 08/11/15 at 17:05:38 Gary, you think the lower-to-upper triple mod could work with upright bars? Might be able to drill new holes in it for the bar risers? Mine is a tracker and yes, the front suspenders are bottoming duds as is. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 08/11/15 at 17:48:18 I'm gonna say no because I'm not sure that the softer aluminum of the lower (now upper) would make a proper support. Perhaps if you are able to make a doubler to spread the load from below. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by singlesgoinsteady on 08/11/15 at 17:53:26 Right I'll take a look at the machined Savage uppers. Also saw them on Dime City. Can't remember if they are made for standard bars. I love your fork mod. The only thing I don't love about my bike. Mostly. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 08/12/15 at 03:52:32 4A50575E555C4A5E5650574A4D5C585D40390 wrote:
I bought the machined upper from RYCA. It was really rough machining and took quite a while to get smoothed out and polished - it appeared the CNC machine was chattering while cutting. I let Ryan at RYCA know, and he was going to contact the machinist. The aluminum is really soft and easy to scratch once it is polished. I believe there is plenty of material if you want to drill it and attach bar mounts.....it is a big solid piece of aluminum. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by singlesgoinsteady on 08/13/15 at 06:10:40 Thanks Dave, at first glance. The other thing I was thinking of trying, but, am limited in my fork knowledge is sending my forks out to get progressive springs, have them and the fork tubes cut & take Ryca spacer out so that I get back to full travel, but, still be shortened in the stock triples. Obviously not as effective at improving ride, but, certainly getting more travel. Clearance would have to be checked. I just don't want clipsons, I want upright bars for my dirt tracker look (and comfort haha). |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by justin_o_guy2 on 10/30/15 at 22:22:13 If I get a toilet seat and a hammer for retail, do I get the lube free? What's the surface you're drilling on? With the spiral grooves,, Very in depth and technical report on the upgrade. How's your ground clearance? I was dragging pegs till the rubber under the right leg required stitches. Baling wire to rescue. Speed bumps nearly dragged the frame. I would enjoy a ride on a hopped up, lightened and tuned suspension...Hafta be a real hoot. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 10/31/15 at 05:05:34 U 6B747275686F5E6E5E66747833010 wrote:
The drill surface in the photos is my drill press. The ground clearance is the same as the RYCA set up because the bike has the same stance. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 11/01/15 at 02:46:51 4A555354494E7F4F7F47555912200 wrote:
I seriously doubt if anyone will be dragging the pegs on a Cafe' conversion. The front is lowered 2" - but the back has been raised nearly 3", and the footpegs are now in the middle of the bike and set much higher than the stock pegs. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 07/01/16 at 06:13:05 Additional Tuning Notes The suspension on a motorcycle is a system. The forks and shocks have to work in balance for good performance and a comfortable ride. This article is focused on the forks and specifically CS-1 Café forks with RaceTech Gold Valve Emulators (GVE) installed. By using GVE you have greater ability to adjust and tune the performance of the forks to suit your needs. GVE allow you to adjust compression damping and rebound damping. But before we get to that, let’s understand what it is that we are trying to balance. We can break this down into four elements: 1. Unsprung Weight – The weight of the wheels, tires and brake components 2. Sprung Weight – The weight of the bike (excluding unsprung weight) and the rider 3. Springs – The part of the suspension that supports the sprung weight 4. Damping – The aspect of the suspension that controls how fast the suspension moves (compresses and rebounds). In sentence structure, the springs support the sprung weight of the bike and rider and damping controls how fast the suspension compresses and rebounds. Simple, right? There are five different adjustable elements to understand to properly tune your forks so they suit your riding style and weight. 1. Fork Springs What do they do? They support the sprung weight of the bike and rider. A spring has a neutral position when unladed (sitting in the box), a static position (installed and preloaded for the bike and rider) and a dynamic position (moving while riding due to road irregularities, braking and acceleration). When in a dynamic position the spring will always be seeking its static position. How are they adjusted? The first adjustment is choosing the correct spring for bike and rider. Once you’ve confirmed that you are using the correct straight-rate spring, the way to fine tune the spring is through preloading. You preload (pre compress) the springs by adjusting the length of the spring stack (GVE, spring, spacer, washers and cap) by adding or removing shims (washers) that are placed between the fork cap and the spacer. If you have adjustable fork caps you can make the adjustments very easily without disassembling the forks by turning the adjusting rod in the fork cap. How do I know when it’s right? There are two types of sag settings that you need to set; static sag; the amount the spring compresses under the load of the bike, and race (also known as total) sag; the amount the spring compresses with the rider on the bike, in a riding position. You want about 10mm of static sag and 25% to 30% of your suspension travel for total sag. This equates to 32mm to 38mm of sag for our 127mm of travel. 2. Compression Damping via Gold Valve Emulator (GVE) What is it? Compression Damping controls the rate (or speed) that the forks can compress. We know that the spring is always seeking its static position. Without damping the spring will seek this position as fast as it can and the inertia of the bike and rider will cause the spring to overshoot its movement towards the static position. Without damping the bike will feel as though you are riding in a rodeo. Too little compression damping results in a fork that goes through its initial stroke too quickly (and feels mushy) and too much compression results in a fork that feels stiff/harsh. How is it adjusted? The GVE is adjusted by selecting the correct spring (yellow, blue or silver) and then preloading it so the valve opens under the right circumstances. For the CS-1 Café application the #40 blue spring is used with a baseline preload of 2-1/2 turns out. Increasing the preload increase the damping (stiffer) and decreasing the preload decreases the damping. How do I know when it’s right? You’re gonna hate this answer, but it’s the truth – you’ll know when it’s right when you like it. If the forks are harsh, reduce the preload on the GVE by 1/2 a turn. If they then feel soft, add back in an additional 1/4 turn of preload. This is an iterative process. 3. Rebound Damping What is it? Rebound damping controls (slows) the speed at which the spring seeks its static position from a compressed position. Rebound is the intersection between ride and handling. Too little rebound and the forks will wallow like a 1970’s Cadillac. Too much rebound and the forks will feel darty/twitchy. How is it adjusted? On forks using GVE rebound is adjusted via the weight of the fork oil. The baseline is 15wt with an air gap of 140mm. Going to a higher viscosity oil increases rebound (slows the rate at which the spring seeks its static position) and a lower viscosity decreases the rate at which the springs seek its static position. An important note on fork oils – there is little commonality between manufacturers of fork oil. So if you are going to go from 15wt oil to 10wt, choose the same manufacturer otherwise you may go from 15wt to 15wt…or 5wt – there’s no way to know. How do I know when it’s right? When the forks provide a comfortable and controlled ride, and the handling feels linear and natural, the rebound damping is correct. 4. Oil Height What is it? The amount of oil in the fork. You are actually measuring the AIR GAP. It is measured from the top of the slider tube to the top of the oil with the fork compressed, GVE in place and the spring out. The baseline air gap is 140mm. How is it adjusted? This one is easy…remove or add oil as needed. It is usually added/removed in 10mm increments for tuning and then as required for fine tuning. For the forks used on the CS-1 Café, each 8.55ml (0.289oz) of oil added or removed equates to a 10mm change in oil height (the forks have an ID of 33mm and solving for this equation gives us the volume of fluid: Volume = Pi x R^2 x Length). To change the oil height just remove a fork cap (one at a time - if you remove both fork caps your bike will sag to its stops and you’ll probably make quite a mess) and insert a hose into the forks and attach it to a syringe to extract or add a measured amount of oil. How do I know when it’s right? If the final 1/3 of travel is too soft and bottoms, add oil in 10cc increments. Do the opposite if you can’t use 85-90% of all fork travel. 5. Stroke What is it? It’s the amount of available fork travel used. It’s determined by the combined effect of spring selection, preload, damping and oil height. As a general rule of thumb, the first 1/3 of fork travel is controlled by the spring and is used mostly for race sag. The next 1/3 of travel is controlled by compression valving via the GVE. The final 1/3 of travel is affected by oil height (air chamber). Ideally you want to use 85-90% of available fork travel; 60-65% for normal riding and 85-90% under heavy compression (like an emergency stop). How is it adjusted? Since it’s the combined effect of everything…it’s everything noted above. With that said, try to only change one element at a time. Fork tuning can be confusing at times. If you change too many things at a time, you have no way of knowing what gave you the desired (or undesired) effect and how to minimize or maximize the change. How do I know when it’s right? You don’t know…until you make a change. If you make changes and like the results…you’re not done. If your changes take you further from where you want to be…then you’re done. Always remember. The forks and shocks work as a system. A change at one end of the bike will likely result in a change at the other end. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 11/06/16 at 18:48:12 Getting the Rear Right I mentioned the shocks above in the tuning guide but didn’t provide any guidance because this “how-to” started life as “fork-centric” and I hadn’t found a solution that I liked for my bike. Having done the necessary research for my bike I thought I’d share the knowledge. As mentioned above, the forks and shocks are a system and need to work in harmony. For example, let’s say you follow every bit of advice given above and get your forks perfectly in the sweet-spot (good for you). If your shocks are too soft or under-dampened your forks will be underloaded and won’t be able to move through their full stroke. Further, soft shocks effectively increase steering rake, making the steering light and vague. If your shocks are too stiff you will overburden the forks, causing you to dial-in an overcompensating amount of rebound during tuning. Remember, rebound is the intersection between ride and handling. Too much rebound and the forks will feel darty/twitchy. But most importantly, shocks define how comfortable the bike will ride. So it’s important for performance and comfort to get the shocks right. What makes one shock better then another? Like the forks, the primary function of the shock is to 1) support the sprung weight of the bike and rider and 2) provide damping to control the speed of movement throughout the stroke of the shaft. Without damping a spring will seek its static position as quickly as possible, overshooting its static position due to inertia. Also, just like the forks, a shock uses oil and air to create compression and rebound damping. As the shock moves it creates heat which is absorbed into the oil. When the oil gets hot it foams within the chamber and if the oil gets too hot it causes cavitation (slipping) within the chamber – impacting the ability of the shock to provide predictable (or meaningful) damping. The faster that heat can be absorbed and dissipated, the better the shock can perform its primary function of providing predictable damping. As a rule: the bigger the oil chamber the more effective the heat management of the shock. Also, better shocks tend to have external adjustments for compression and rebound damping. This allows the rider/operator to dial-in (fine tune) the shock without having to remove the shock and make internal damping adjustments via the valving stack. Let’s review the various types of shocks that are “reasonably” available for bikes like ours. Shocks come in three basic styles; Twin-Tube, Gas-Emulsion and Reservoir (piggyback reservoir & remote reservoir). Twin-Tube shocks are the type most typically seen on budget bikes. They are self-contained with an inner oil chamber and an outer air chamber (hence, the twin tubes). The damping rod (shaft) is connected to a piston that moves through the oil, creating damping. The vast majority of these shocks are typically low performance, non-rebuildable, provide fixed damping and only adjustable for spring preload (usually just 5 positions for spring preload). Advantages – usually cheap ($50 to $200 pair). Disadvantages – limited adjustability, fixed dampening, small oil chamber and non-rebuildable, so when the damping no longer meets your needs you throw them away. Best use: play/monkey bikes, around town bikes. Emulsion shocks (sometimes called gas-pressurized) are next on the shock hierarchy and offer a significant improvement over twin-tube shocks. Emulsion shocks are single tube shock that have a self-contained reservoir that separates the oil and air. Because of this they are not quite full of oil because they require an air space to deal with the displacement of the shock shaft. The better emulsion shocks use nitrogen instead of air and therefore are called “gas shocks”. Nitrogen is desirable over air because it doesn’t expand/contract with temperature changes like air. This is a desirable attribute since the shocks have a small gas/air chamber. The gas is compressed (pressurized gas) to raise the temperature and lower the pressure that cavitation occurs within the chamber. Once cavitation begins, the shock no longer provides meaningful damping. Advantages – not terribly expensive ($200 to $600 pair depending on features), typically rebuildable (including the damping stack/valving so the high-speed compression can be customized for your bike and riding style), typically infinite adjustability within a range for spring preload and on higher spec units adjustability for low-speed compression. Disadvantages – relatively small oil chamber so they don’t manage heat well. Best use: street bikes where the rider enjoys a comfortable ride and doesn’t do much “spirited” riding. Up next are gas-pressurized reservoir shocks, both piggyback and remote. The difference between these two types of reservoir shocks is the size of the oil chamber and their ability to absorb and dissipate heat. Since the remote reservoir is detached from the shocks, it can more effectively manage heat (on higher-end units the valving is also in the remote). Because of this defining feature these types of shocks are usually considered “high performance”. Otherwise everything mentioned about gas-emulsion shocks applies to this type of shock. Advantages – large oil/gas chamber so they manage heat extremely well, typically rebuildable (including the damping stack/valving so they can be customized for your bike and riding style), typically infinite adjustability within a range for spring preload and on higher spec units adjustability for low-speed compression, high-speed compression and rebound. Disadvantages – expensive ($400 to $1,200 pair depending on features). Best use: track bikes. The above is generalized but is a good primer and provides a basic knowledge of shocks. The shocks found on the vast majority of budget bikes are of the twin-tube variety. So it’s no surprise that Suzuki uses twin-tube shocks on the LS650/S40. RYCA also supplies twin-tube shocks in their kit that appear to be the same quality as the OEM shocks. Unfortunately the shocks supplied by RYCA are under dampened (a design limitation) and to compensate for the poor motion control, they are also over sprung – the worst of both worlds. But if we’re being honest, if you’re riding with the RYCA fork solution, you’ll probably never notice the crappy shocks. If you have taken the time and spent the money to improve your front suspension, by now you are probably very unhappy with the shocks. So if we are going to improve the shocks to work as well as the forks, what do we need/want? First consideration is shock length. Turns out the RYCA guys got this spec spot-on. The kit shocks are 13” (330mm) eye-to-eye (from the center of the upper mounting hole to the center of the lower mounting hole) and can’t really be much longer. I tried a length of 13-3/8” (340mm) and experienced some chain contact at the front end of the swing arm during braking and bumpy road surfaces. It’s barely noticeable but I went back to 330mm and the contact was gone (335mm is probably a safe length). I wanted to experiment with the longer length to see if a rake of 26-27 degrees would improve the handling, but I found the steering to be a bit light for my liking. I could have made adjustments to the forks to compensate, but with the chain contact it wasn’t worth any of my effort. 13” works perfect. Another consideration is spring rate. A RYCA conversion is a light bike with most of the weight bias towards the rear end. My bike weighs 330 lbs with fuel (157 front / 173 rear) without me and about 500 lbs with me (222 front / 278 rear). Since we don’t have a link suspension, we want progressively wound or dual-rate springs. We need shocks with 14mm mounting eyelets. We need shocks that provide more than 2 inches of travel. The short stroke is a result of cramming everything into one tube (oil, air chamber, valving, piston, rebound spring). This is also another reason why a reservoir shocks are desirable – they inherently provide more stroke. So with the above information I decided to identify shocks for my café racer with the following criteria: - Adjustable length that allowed for lengths in the range of 330 to 340mm. - A reservoir type shock for the extra performance and additional stroke/travel. - A fully rebuildable shock so the valving can be suited to the attributes of a light-weight café racer. - External adjustments for compression and rebound damping would be “nice-to-haves” but not necessary because once the valving is correct, I typically don’t make further adjustments (just like our forks). - Here was the hardest one, I didn’t want to spend more than $500 for the pair. There are many choices for shocks above $500 (closer to $1,000) from Fox (Podium), Ohlins (36P), RaceTech (G3-S), YSS (G-302) and Progressive (970 Series) to name a few. And then there are knock-offs of some of the above shocks that are typically below $100. I didn’t want to spend $700 to $1,200 for the originals and didn’t want to bother with the knock-offs. There are always questions and skepticism about the quality of the knock-off shocks. In forums these questions usually quickly dissolve into arguments between people who have never used them who claim they are junk to people who own them and say they work. I’ve seen every claim on the junk side including they are made of pot metal and will disintegrate to there are no actual components (valving or piston) inside the shocks. On the surface this could be believable, and in some cases maybe even true. But there are a few knock-off manufacturers that seem to get good reviews form people who actually have used them, namely RFY and TEC. The RFY and TEC reservoir shocks look a lot like a the Ohlins 36P or HO-142 shock (not a high-end racebike unit with external damping adjustments, but a good streetbike version that is fully rebuilable/adjustable) but they are a fraction the cost. At that price point can they actually be a viable option? On several of the places I was doing research (CB350 and Triumph forums) there was a gentlemen by the name of Chris that actually had experience rebuilding shocks and decided to do a tear-down and conduct a comparison of RFY shocks to Ohlin shocks. His findings were shocking (get it?). He found that the RFY copies are quite faithful to the originals. Moreover, he felt that the only thing that would keep him from recommending these shocks as an inexpensive streetbike shock was its set-up. Over time he developed a good working understanding of the RFY and TEC shocks and began to offer a rebuild service, as well as a custom build-to-order service of these shocks. It was the custom build-to-order service that caught my attention because if I decided to try this inexpensive alternative I knew they wouldn’t work on my bike out of the box. Further, I also do not possess the proper specialized tools to conduct a proper rebuild of a pair of shocks. Finding someone that could get the shocks right the first time took the risk out of the equation. So I provided my personal needs and my bike needs to Chris, and for a little over $200 I had shocks that worked out of the box for my bike. These custom/rebuilt RFY shocks checked all of my boxes: - Adjustable length that allowed for lengths in the range of 330 to 340mm. - A gas-pressurized reservoir type shock for the extra performance and additional stroke/travel of 2.75”, an improvement of ¾ inch. - A fully rebuildable shock so the valving has been built to the attributes of my café racer. - 14mm top mount and eyelets. I hate to sound like a fanboy, but the shocks completely changed my enjoyment of my bike. Simply put, these shocks work. My rear suspension now matches the performance and comfort of my forks. The suspension is finally in balance. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 11/06/16 at 18:48:56 (continued from above) If you have the tools (spring compression too, spring dyno, nitrogen) to rebuild and valve the shocks yourself these shocks are well worth your time, money and effort. They are well suited to the LS650/S40 platform. If you know a good reliable suspension shop, I wouldn’t hesitate to have them rebuild a pair of RFY for your needs. This may be an iterative process with your shop. If you want to order a pair of shocks and be able to install them when you receive them, contact Chris at CL Mototech at the website below. There shouldn’t be much (or enough to matter) difference from bike to bike, so replicating my shocks will be straight forward. I expect Chris will need to know the rider weight which may impact spring rate and valving. http://chrislivengood.net/wp/product/fully-built-shock-package/ Article of RFY Type 1 teardown http://chrislivengood.net/wp/rfy-shocks-overview/ Click through Chris website for a lot of good info. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Armen on 11/07/16 at 17:41:20 Thanks for the in-depth write up, Gary! When you refer to 2" of travel or 2 3/4" of travel, are you referring to the actual amount the shock compresses, or to wheel travel? The shocks are set inboard of the rear axle, so 2" of shock movement would translate into more than 2" of wheel travel. One of the things that always made me crazy about Harleys is that a lot of them have about an inch of shock travel and 2" of rear wheel travel :-? thanks, -Armen |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 11/07/16 at 17:50:17 The travel figures are at the shock, not suspension travel. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Armen on 11/08/16 at 03:07:41 Thanks Gary. Have you calculated rear wheel travel with the new shocks? I'm ordering a set this week. Thanks for the well written article and the lead! |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 11/08/16 at 04:55:04 1D2E3139325C0 wrote:
I haven't but I've been thinking about it. I'll talk with one of our mechanical engineering during lunch to understand the kinematics. 1D2E3139325C0 wrote:
You're gonna love 'em. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Armen on 11/08/16 at 05:04:46 When I get mine, I'll yank the springs, mount them, and measure the wheel travel. All that thinking makes my brain hurt ;) Are you running an 18" or 19" front wheel? Still have the 19" on mine. Prob end up with an 18" thanks |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Gary_in_NJ on 11/08/16 at 06:05:28 I went with the 18" front. I wanted to improve the steering feel and quickness and the 18" front improves the rake. The 18" front also has a lot less gyroscopic effect, making for lighter/faster steering. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Armen on 11/08/16 at 06:26:58 Yup. My thinking as well. For now, I'm just trying to get the bike on the road. The rear wheel ended up costing about $600 with all the bells and whistles, so I have to pace myself a bit. The 18" will also improve braking a tiny amount. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Dave on 11/08/16 at 14:48:28 And....if I can be a "buttinski".....I am running a 100/80-18 and/or a 90/90-18 front tire, and they provide all the tire that this relatively lightweight bike needs. The 100/90-19 and 100/90-18 tires are far bigger and heavier than these smaller tires. |
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Title: Re: Fork Improvements for RYCA Café Conversions Post by Armen on 11/08/16 at 15:11:09 Dave, Yup, got that. I ride a lot of customer bikes with 'full figured' front tires, and try to explain to the owners that the bike handles worse with wider tires. |
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Title: Re: Fork & Shock Improvements for Café Convers Post by Gary_in_NJ on 11/12/16 at 19:12:46 Armen, Turns out your question about how does shock stroke translate into suspension travel is a great question. Your method was enlightening too. It also turns out that RYCA was spot on correct in choosing an eye-to-eye (E2E) of 13 inches. Since my bike is apart for paint I had an opportunity to test various shock lengths to see how it affects suspension travel and chain contact at the leading edge of the swing arm. Having the bike on a table/stand made this test very easy. Here is the test setup: - Front wheel in a fork and the bars strapped to the table simulating a race sag condition of 35mm compressed - Hydraulic jack at the base of engine case - Shocks removed - Tie-down strap attached between the upper and lower shock mounts on right side of the bike - Kenda Cruiser K671 130/70-18 Rear Tire - Rear tire pressure at 32 pounds - 1-1/2” of chain slack With the above setup I was able to raise/lower the bike to adjust the distance between the upper and lower shock mount. This enabled me to see at what shock length the chain made contact with the swingarm and by using a tie-down between the shock mounts, raise the rear tire to see what suspension travel is at different shock lengths both fully extended and fully compressed. Let’s look at the Goldilocks length of 13” E2E. The RFY Model 1 shock has a stroke of 2.75”, resulting in a compressed length of 10.25”. Fully compressed, the chain is about as tight as you’d want it because at a compress length of 10.125 you can no longer raise the rear wheel because of chain tension. The tire is difficult to turn at 10.125”, so a compressed length of 10.25 works out well. Also, at an E2E distance of 12.75” with the chain tight, the chain makes contact with the swing arm, just barely. At a E2E length of 13” with a fully compressed stroke of 10.25 inches there is 4.25” of suspension travel. This is an important figure to know for setting sag (static and race). With an extended shock at 13”, the top of the shock mount bolt is 25.75” from the ground. Allowing for about 10mm of static sag (the weight of the bike only) and the top of the shock mount at 25.375” from the ground, the E2E distance is 12.625” and the chain is clear of the swing arm. I simulated a shock with an E2E of 13.125 and at this length (4.5” travel, 26” top of the mount) the sag setting is 25.625” at the top of the mount resulting in an E2E distance of 12.75” and the chain making contact with the swingarm. For several reasons 13” E2E is the maximum length (with the RFY Model 1 shock with 2.75” stroke) you can use. Just 1/8” longer and the chain makes contact with the swing arm and the chain is at maximum stretch. |
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Title: Re: Fork & Shock Improvements for Café Conversions Post by Armen on 11/13/16 at 04:50:15 Hey Gary, Thanks so much for taking the time to do all that work, document it, and post it. I'm ordering a set of shocks this week. Was going to last week, but ended up replacing my furnace, so I'm in a bit of sticker shock :-? I'm running a belt on mine. With the 2" travel RYCA shocks, the belt goes from crazy loose to pretty tight during it's travel. Wondering if the additional .75" of shock travel will make the belt tension even crazier. I'll dummy it all up when I get the shock. Worst case scenario, I'll make spacers to go between the shock bumpers and the top shock mount, and kill a bit of travel to reduce the range of belt slack. And still have a sexier shock in terms of damping. If my math is correct, the wheel moves about 1.545" for every 1" the shock moves. Reducing the shock travel by .250" will still give 3.86" of wheel travel, which is prob enough for me. And more than the 3.09" afforded by the RYCA shock. More stuff to do in my abundant spare time... |
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Title: Re: Fork & Shock Improvements for Café Convers Post by Gary_in_NJ on 11/17/16 at 19:27:39 With my bike in a stand I decided to take some rake and trail measurements. My table stand is exactly level no no adjustments were required. The tires are inflated at 32 front and 32 rear. I performed the test with the suspension extended and at its race sag setting (35mm front and 30mm rear). Not surprisingly the rake figure was about the same in both configurations. Rake is at 28 degrees and trail is 3.5 inches. I expected the rake to be in the 27 degree range because that was the result I had with the prior shocks. But those shocks were much stiffer - the sag setting of the RFY shocks is more then 1/2 of the full travel setting for the RYCA shocks. The the trail number surprised me. I don't know why, but I expected this figure and to be in the 4.5 to 4.75 range. In any event 28 degrees rake and 3.5 inches of trail explain the light steering and flickable nature of the bike. |
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