|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> 12 USD Carburettor /cgi-bin/YaBB.pl?num=1686395619 Message started by Moarpower on 06/10/23 at 04:13:38 |
|
Title: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:13:38 So my 17aud carb arrived. It is packaged quite well with some blatant ripoff labels etc. Fit and finish is poor with machining marks externally and sharp casting edges. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:14:22 Another shot. The fake Sudco sticker is nice lol |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:14:57 Atleast the ports are smooth |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:15:28 No idea as to the needle size here but it was listed as DDJ I think |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:16:04 160 main jet |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:16:35 pilot jet. These are going to be useless for me. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:17:14 Slide spring. Seems fine |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:18:49 I don't want to sacrifice my factory cable so I always have one of these repair kits on hand for my kids' dirt bikes. It will be fine for testing . I'll not use it on the road for any length of time if the carb works. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:20:37 The cable connector came pre-rounded off! but hey for 12 bucks, ill order another |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:21:36 A brass end on the cable almost fit so I just had to open the throttle cable connector a little with a drill |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 04:22:23 Now im just waiting for the new jets to arrive. Looking forward to giving it a go. I know this slide needle will be an issue. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 06/10/23 at 18:56:08 Carb looks good to me, but I think you might have ruined the contraption that the cable hooks in to. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/10/23 at 21:46:50 All I did was deepen the hole. It was already rounded off and the casting was God awful so it's just a throw away part to me. Just has to work for testing. If the carb works I'll buy a genuine part to replace it. Wasn't worth ruining my current cable just in case. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 06/11/23 at 19:54:35 The cable doesn't go all the way through the contraption. The cable hooks into the top of the contraption. You install the contraption first, then you hook the cable into the contraption. That brass piece isn't necessary. Like this. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 06/11/23 at 20:04:17 The bottom of the contraption captures the e-clip on the slide needle. It sets the height of the needle. Your enlarged hole will possibly permit the e-clip to float up & down. You don't want the clip pinched by the contraption, you want it to have just a little wiggle. There is a shallow counterbore in the slide that accepts the e-clip, then the contraption captures the e-clip when you install the contraption. You want the needle free to wiggle around side-to-side, but have almost no up & down play. Your enlarged hole might screw that up. I've tried installing washers under the e-clip to make fine adjustments on the needle. That doesn't work. It wrecks the e-clip because it gets pinched. You want the needle to be able to wiggle around side-to-side but have no movement up & down. See how the e-clip sits nicely against the bottom of the contraption. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 06/11/23 at 20:09:05 In addition to the e-clip issue, now your cable swage will sit right on top of the needle. It might prevent adjustment. If you want to raise the needle, the cable swage might interfere. Worse yet, if the swage sits low enough, when you tighten the contraption the swage will hit the needle and break something. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/11/23 at 22:49:31 Thanks Mike. The purpose of this was just to see if the carb itself will function at all as I have my reservations given the price. I wasn't willing to modify my stock cable until I am certain. Once I have the different jets and have tested it as working, I will replace the cable and the cable attachment with factory parts. I have also ordered a couple of needles and jets to try. As it is, I can swivel the needle and move it side to side but there is no up ad down movement. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/12/23 at 01:10:33 Well I can certainly say the carb works. And while it isn't currently tuned for the savage, I'm impressed that a 17aud part works at all. I'll buy a used Suzuki ls650 throttle cable and make it work by referencing the guides on this site. It certainly has some more power at WOT as it stands out of the box, but the slide needle is way off. And the pilot is way too big. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 06/17/23 at 17:11:23 Might as well grab another for the kids dirt bike at this price. Anyone I. Australia, they have 2 left |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/08/23 at 03:07:53 Inset up the new 12 dollar carb and made a new cable as I discovered the original was badly frayed at the throttle grip end. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/08/23 at 03:08:25 Like a glove. ...almost |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/08/23 at 03:19:55 Thanks Fast_650 for the tips. I can see this carb is going to be a huge pain in the butt while playing with jets and needles. With the needle that it came with the slide would not fully seat into the short 140 main jet I fitted. I guess it requires the tall jets to seat the needle fully. Seeing as my factory carb is rubbish and the cable was trashed, I decided to mess with the cheap needle. I tapered the end until it it fully seated and the slide closed. I put the clip in lowest slot. 140 main and 35 pilot I could only get it to idle with the choke out. Stepping up the pilot to a 38 achieved a good idle. But the idle adjustment screw (which is plastic) made no change even when fully in. I used a shorter spring and this worked well and I was able to get it to idle well. I took it for a spin. darn it was faster. 90kmph in 2nd and WOT was awesome. Idle was smooth and the spring return of the slide was nice and snappy. Cruising however, not great. It was breaking up, kind of similar to a rev limiter. So I need to sort the needle issue. I ran out of time but I'm looking forward to doing more through the week. With the cable fitted, removing the slide is a huge pain. Are there any tips for quick and easy needle adjustment and swaps or is this setup just a massive pita with the cap and spring setup. |
|
Title: Re: 12 USD Carburettor Post by Surviving Philly on 07/08/23 at 06:50:25 Has a sticker that reads "for motorcycle RACE use only" ;D |
|
Title: Re: 12 USD Carburettor Post by Fast 650 on 07/08/23 at 12:10:06 61434D5E5C435B495E2C0 wrote:
Take the cable off at the grip to gain more cable length. That will give you more slack at the slide then. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/08/23 at 13:19:50 Of course! Thanks for that tip. Definitely more involved and tedious than the stock carb but that will make it easier. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/08/23 at 15:14:15 I move the needle up two slots and reassembled and installed the carburettor. The one downside of this carb is that it is much more painful to adjust the needle settings. Messing with the spring and cap is a huge pain. Getting the cable anchor threaded in while holding the spring out of the way is very tedious. When I installed with the new clip settings immediately noticed that I would need new jets as the short jets do not seat the needle correctly and dislodge the clip on the needle. I returned the clip to the lower setting and then had a hard time getting the bike to start and run. When I had it back together the snappiness of the slide return spring was nowhere near as satisfying as it was and it was quite loose. So I obviously messed something up. Had to go away for a couple of days but I will get back into it when I get home. I have a lot to learn with these carburettors I got quite efficient at pulling down and reassembling the factory carb very quickly to change the needle and jets when needed. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:20:32 "I decided to mess with the cheap needle. I tapered the end until it it fully seated and the slide closed. I put the clip in lowest slot." You really should stop hackin away at these critical parts. You mentioned you are using some sort of "short" main jet and that the short jet interferes. Why would you use any main jet other than the intended main jet? If you have a standard style PWK, the you should be using the standard style main jets. That would be these. https://www.jetsrus.com/a_jets_by_carburetor_type/jets_keihin_99101-357_main_Hex_25-xxx.htm |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:23:25 I can see from your photos that your cable swage is still waaaaay too big. The cable swage is supposed to go up in the cable hook and seat in a recess. It should look like this when it is seated correctly. See how the swage goes up into the socket. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:24:57 If it looks like this, then the swage is still too big. If the swage doesn't go up into the socket, it will always want to slip out of the hook. It will be very difficult to install. It can come out while you are riding and leave you stranded. So, not like this. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:29:20 "I used a shorter spring and this worked well and I was able to get it to idle well." Shorter spring where? Slide or idle stop screw? |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:36:39 "With the cable fitted, removing the slide is a huge pain. Are there any tips for quick and easy needle adjustment and swaps or is this setup just a massive pita with the cap and spring setup." "The one downside of this carb is that it is much more painful to adjust the needle settings. Messing with the spring and cap is a huge pain." "Getting the cable anchor threaded in while holding the spring out of the way is very tedious." I personally find the PWK fairly easy to work on, about the same as a Mikuni VM. Once you understand how the thing goes together it goes pretty smooth. First off, Fast650's suggestion on disconnecting at the twist grip first is a good place to start. Next, never try to install the cable into the hook and then screw the hook into the slide. Jeeeez, that's gotta be hard. How did you ever do it. Install the needle into the slide and then thread the hoouk into the slide to capture the needle. Lightly tighten the hook. It should look like this. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:39:07 Then pull back the spring and nylon lock ring and use a pair of surgical clamps to hold everything in place. You have to fight the spring a bit but that's typical of any carb like this. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:40:24 Then push the cable swage into the hook and pull up so that it goes tight in the socket. Like this. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:42:32 Then release the surgical clamp and lower the locking ring and spring on to the hook assembly. Make sure the tab on the nylon lock ring aligns correctly with the cable slot. Now the cable is captured. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:43:04 Ready to rock-n-roll. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/08/23 at 19:44:35 Just a note. I did this demo on top of my kitchen stove because there's good lighting for the photos. I find it harder to do on top of the kitchen stove than on the bike. On the bike, the cable isn't floppin all around. I suspect you need a new slide needle. Got any pics of what you did to it? |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/08/23 at 20:54:20 Thanks Mike. Those surgical clamps are going to be needed. I used zip ties. What a pain. I'll post pics of the needle when I get home. Basically, because it's a cheap part, I added a slight increase to the taper. For some reason it wouldn't allow the slide to lower all there way with the short main jets I stalled. I reinstalled the tall jet and it seated all the way down. I have ordered a few smaller sizes in the taller jets. I just need to decide what needles to get. I'll buy 2 to try for now. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/16/23 at 03:13:21 Using the shorter keihin jets is not going to work with this carb needle. The needle pokes through far enough to impact the shorter jets. The taller jets have a larger hole in the threaded end. I've attached a picture of how far the needle pokes out. I managed to get it idling well today with the 35 pilot. I used a tall, 130 or 135 main (uncertain as the number on it was worn off but I used small drill bit to determine its between 130 and 135. I reassembled and was quite disappointed as the really nice snappy throttle feel was gone and it was feeling very loose now. I got rid of most of the slack at the handle end but it really didn't feel like it did at first, which was quite stiff with the spring and really nice to use. Not sure what happened. Maybe I've reassembled wrong but I pulled the cap off again and re assembled the spring and it was still the same. Let it warm up and then out for a ride. It's much better than the stock carb. More responsive, and noticeably more power. It rode well all through the rev range, no bogging or surging at idle, Wot or while cruising at part throttle. 2nd gear would get to 90kmph easily. Only back fires were when closing the throttle and slowing down at high revs. When idling there is one issue. Snapping the throttle open quickly would bog the bike right down to near cut off. However, doing it again soon after it would rev fine. Opening the throttle at a speed slight slower than instant also worked fine. Onam looking for the needle DBM recommended. So far I can find them and ship from the USA. 18aud for the needle and 35aud shipping lol. I've emailed local retailers and I'll see what they say. The issue may also be related to float height which I'll check tomorrow. I really would like to fix the throttle feel too. The throttle feels very loose which is very strange as it is connected directly to a spring. Maybe a kink in the cable? But it moves both way very lightly with no resistance. Annoying. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/18/23 at 02:28:37 It's riding really well. Much more power than stock but I can tell the needle is a little lean. I have ordered a DGK needle that will hopefully be here by Saturday. I have attached a video of the bogging when I rapidly open the throttle. Interestingly, I don't feel the issue when I'm riding l, even if I take off fast from a stop. 17aud well spent. https://youtube.com/shorts/lN7ILSbcCHQ?feature=share |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/20/23 at 03:20:09 I went for a ride today running the included needle which I believe is DDJ, 135 main and 35 pilot. This is the plug after 70km. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/20/23 at 03:21:34 I've stepped up the pilot to 40 and will try the 138 and 140 main jets . But j think this plug looks either hot or lean? It's hard for me to tell as I'm colour blind. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/21/23 at 15:57:03 I finally received the DGK needle as recommended by DBM. He also recommended the EGK which is richer but it was not available from the Australian supplier of Keihin/Sudco. VS the DDJ needle, power delivery felt less harsh and the engine sounded better. The DDJ was undoubtedly on the leaner side but it still worked. I set the DGK at position 3 and it was quite good. I did notice after around 40 minutes of riding that I could get it to break up a little at the top end, around 3/4s to 4/5s throttle. But only at high revs. I'll move it to position 2 and see if that helps as it felt rich. Unfortunately, there has been no change to the quick throttle bog while idling. I am wondering if it could be my massive air-filter? |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/27/23 at 03:05:02 Hey guys. So my journey through building this bike and messing with things has been great. Ive got the new carb (12usd) running really well now. The DGK needle gave me rich bogging at steady high revs at positions 2 and 3. Moving it to position 1 has really minimised it. Hopefully not too lean tho. Running a 140 main and 40 pilot. I am hoping to make sure I have an appropriate slide cutaway. Hopefully, DBM will chime in with some wisdom on how to identify this. This is the slide I have. No marking anywhere. |
|
Title: Re: 12 USD Carburettor Post by TheSneeze on 07/27/23 at 06:48:49 http://suzukisavage.com/cgi-bin/YaBB.pl?num=1625732492/60 Reply #67 shows how to identify your slide. |
|
Title: Re: 12 USD Carburettor Post by Dave on 07/27/23 at 07:58:44 01232D3E3C233B293E4C0 wrote:
When I installed my VM38, I had an oxygen sensor and display meter on the bike so I could see what was happening with the fuel/air mixture while I was riding. It showed me some things that were contrary to what I believed was happening. THROTTLE ROLL OFF - EXHAUST POPPING. I had thought that the popping noise out the muffler was caused by the mixture going rich as a result of the air supply being closed off by the slide. It turns out that just the opposite happens and the mixture goes so lean that the spark plug can no longer ignite the mixture and often the fuel/air mixture goes out the exhaust valve and gets ignited in the hot exhaust system (POP/BANG). Evidently the high vacuum caused by the closed throttle can pull more air past the partially closed slide than the fuel coming out of the idle circuit can support (The slide needle has closed off the fuel flow from the needle jet)....and the mixture goes very lean. The TEV (Throttle Enrichment Valve) on the stock carb is supposed to open and provide an extra dose of fuel when this happens......there is no similar circuit on aftermarket carbs. This scenario is common on any motorcycle with a big piston/cylinder, a carb and a free flowing muffler.......just think how many Harleys you have heard popping and banging as they slow down. You really should not be richening up your pilot jet or opening your mixture screw to cure this - as you will be running an overly rich mixture while idling or at low speeds. You can reduce the severity of the noise by adjusting your idle speed a bit higher, or using your right hand to lightly open the throttle to provide more fuel flow (just open the throttle enough to reduce or stop the noise.....not so much that you are actually accelerating). THROTTLE OPENING - Whenever you open the throttle the fuel/air mixture goes lean. As the slide opens the vacuum in the carb throat is reduced temporarily....and it takes a short amount of time for the engine to respond and the vacuum to return to the same level that existed prior to you moving the throttle. The slower you open the throttle the lower the vacuum drop will be. This reduced vacuum results in just a bit less fuel being pulled out of the jet needle. The faster you open the throttle the more you reduce the available vacuum beneath the slide where the jet needle is located.....and the leaner the fuel/air mixture becomes. The stock carb has throttle butterfly and a vacuum operated slide (CV Carb.....Constant Velocity), and the goal is to keep a proper amount of vacuum and a proper fuel mixture - the carb is doing the work to keep the slide from raising too quickly. (Some carbs have an accelerator pump to provide the extra fuel needed when you open the throttle quickly). With a carb that has a manually operated slide and no accelerator pump - you are the one controlling how quickly the carb opens and the resulting fuel/air mixture. You should get into the habit of "rolling" on the throttle - rather than just wacking it open and putting the fuel/air mixture into a very lean condition (that can result in the engine bogging until the vacuum and proper fuel/air mixture return). STEADY CRUISE AND JETTING - When I was jetting the carb and could see the fuel/air mixture on the meter, I jetted so that the mixture was richer than 14.7;1 while the throttle was rolled open, and less than 12.5:1 during steady cruise. ADVICE - Don't be overly concerned about a bog if you crack the throttle open from idle.....that is really not a situation that will occur while you are riding, and it is a scenario that really exaggerates the primitive nature of a carb. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/27/23 at 21:43:12 Moarpower, just as Sneezy said, see reply #67 to the old post. On that page, it gives all the details on slide measurement. You should have a #7 slide. A letter "W" drill bit just fits under the leading edge of the cutaway. As far as markings go, a genuine Keihin slide has a logo and the slide number on the bottom of the slide like the attached picture shows. Here's what a genuine slide marking looks like. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/27/23 at 21:55:59 Here is a video of my bike's throttle response. I can snap it open pretty fast and there is instant response. That's with a #8 slide and an "EGK" needle. A #7 slide should be better. The video also shows how the bike tolerates a chopped throttle. Note that towards the end of the video, I repeatedly accelerate and chop the throttle. No backfires, no kabooms. You shouldn't have to hold the throttle open or set the idle extra high in order to keep the thing from backfiring. I set my idle at about 1300 rpm, and when I decelerate, I simply chop the throttle completely. As Dave mentioned, you can see that the fuel air mixture goes grossly lean when I decelerate, but there's no backfire. I don't know exactly why these bikes backfire, but my experience has been that the slide needle plays a bigger role than the pilot jet or the idle mixture screw. Again, I can't explain why, it's simply been my experience that when I get the slide needle squared away the backfire is gone. That has been my experience with the PWKs, the VM, and the stock carb. https://www.youtube.com/watch?v=1SEvGojazP8 |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/27/23 at 22:12:15 Here is a video of how the PWK works on a normal freeway merge. It runs smooth, pulls hard, and revs willingly. No hicups or hesitation, no misfire. https://www.youtube.com/watch?v=T58wkGD8VjQ There isn't anything special about my carb. Other than the smaller main air bleed I installed, it's just basic tuning. No add-on power jet or intelijet or thunderjet or dial-a-jet. Just regular tuning. It ran pretty much the same with the .075" air bleed too. If your carb doesn't run similar to this, then something isn't right. You shouldn't need a more restrictive air cleaner. That's moving backwards, depriving the engine of air. I have a very large K&N air filter. It works fine. It is possible to force a carburetor to work a bit better by restricting the air filter, but that's simply covering up the real problem. If you have a #7 slide, a .110" needle jet, a .075" main air bleed, and that DGK needle, it should run similar to mine. How did you install the carb? Is it on the stock manifold? If it's on the stock manifold, did you replace the stock clamp with the special Ideal clamp? Have you checked the manifold for air leaks? ThumperPaul had a lot of trouble with his PWK and it turned out to be a leaky manifold. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/29/23 at 10:56:52 I forgot to mention, the DGK needle is a leaner needle than the DDJ. I must clarify. The DGK is leaner from 1/8 to 1/4 throttle, but richer from 1/4 to 3/4 throttle. DBM 8/1/23 It's a knockoff so no way for you to know if the as-delivered needle is in fact a DDJ. The DGK has a slightly larger basic diameter (2.695 vs 2.685), and the taper starts farther down the needle (39.95 vs 36.80). Both needles have the same taper (1 degree 45 https://jetsrus.com/a_jets_by_carburetor_type/needle_keihin_N427-48.html I believe you mentioned that you have the needle clip in the top groove. That should be pretty lean. I would be careful with that. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/30/23 at 22:40:16 Thanks Mike. I thought the DDJ was leaner. I assumed that the bogging when backing off the throttle was from it being rich as it was worse with the clip in positions 2 to 5 |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 07/31/23 at 10:37:16 My comment on the DDJ vs DGK was simply to let you know where the two needles fall on the lean/rich scale. The link to the needle chart should be useful. It's very important to know where a particular component falls on the lean/rich scale so you can arrive at an informed assessment of any particular change. If you install a needle that you believe is richer, when in fact it is leaner, you will obviously arrive at an incorrect assessment of how the change worked and what to try next. That's why I previously warned you about cheap jet kits. It's hard to express in words how an engine is running, and you & I use different terminology to describe things. At this point, I have no idea if you are rich or lean. I simply want you to be aware of where a particular part falls on the lean/rich scale. Not having solid confirmation regarding your main air bleed, your needle jet, and your slide cutaway makes any sort of assessment close to impossible. What about the clamp on your manifold? Did you install a good clamp or is the stock clamp on there? |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 07/31/23 at 23:56:59 A good clamp the type suggested here on the forums is what Im using. It gets nice and tight. Slide is a number 7. Reading the needle charts is melting my dyslexic brain. Graphs and things I really struggle with. The DDJ and DGK both seem to run well right up to the last little bit of throttle before the main jet kicks in. They both sputter like they are going rich at that point and my only choice is to move to clip position 1 which I fear is a little lean as the bike is running hot but the sputtering stops. I assume that the final taper is slightly too rich? IM not sure if changing the main jet will have any effect but I will see if it does. Is there any needle closer to the EGK or DDJ (The DGK is a little lean) that will be slightly leaner at the end? Ideally, Id like to run in position 2 or 3. Ill try again to understand the needle chart. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/01/23 at 13:06:38 I must apologize, I gave you some semi-bogus info. I have been struggling with your problem, trying to understand what is going on with your bike. As a result, I keep going through needle charts and my old notes. Last night I realized I had given you some misleading info. I told you the DGK was a leaner needle (leaner than the DDJ). That is not exactly correct. The DGK is leaner at 1/8 to 1/4 throttle, but it is richer at 1/4 to 3/4 throttle. That's important since your problem occurs at the higher throttle openings. I have to correct my post. Your concern over being too lean is valid. You can hurt it with a lean mixture. One thing I noted on my bike was that the DGK needle had a tendency to control fuel delivery at wide open throttle. Typically, you want the main jet to be the controlling orifice at WOT. The needle and needle jet should be out of the picture by the time you get to WOT. That's why I switched to the EGK needle. The EGK has a steeper taper (2 degrees vs 1 degree 45 minutes). The EGK is richer than the DGK from 1/4 to 3/4 throttle. Note that the needle chart only shows the needle's effect from 1/8 to 3/4 throttle (1/8 to 1/4 horizontal top bar, 1/4 to 3/4 vertical side bar). The needle should drop out of the picture past 3/4 throttle, and the main jet should be controlling the fuel delivery. But you seem to be affecting your WOT mixture when you drop the needle position by installing the e-clip in the top groove. That indicates that your needle is controlling WOT mixture. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/01/23 at 13:15:54 I believe you are now running a #140 main jet. That should be enough main jet, but you have a misfire at very high rpm, and to clear the misfire you drop the needle to the lowest position (your position 1). Do I have that correct? If that is correct, then you are clearing up your misfire at WOT by leaning out the mixture, but a #140 main jet is simply not large enough to cause a misfire under those conditions. Are you still running that straight pipe with the baffle inside? I went back through all your old posts. You have been struggling with this high rpm misfire for several months. You had the high rpm misfire with your stock carburetor too. 5/21/23 you said: “The only issues I found on the ride today were at very high rpm. I'm not sure if it was in need of air or fuel. I could try a larger main jet if that might help? The hesitation/stuttering is only slight and at what feels like the top 10% of the rev range at WOT” You got things cleaned up pretty good by installing a decent air filter, but you still had the slight misfire at WOT. I believe in one post you removed your exhaust pipe extension with the baffle and it cleared up. 5/23/23 you said: “Ok, a quick and dirty test with no intake and open header seemed to rev out well in 2nd gear. I didn't do it much, just 3 or 4 pulls. Bur it was responsive.” Yesterday you said: “The DDJ and DGK both seem to run well right up to the last little bit of throttle before the main jet kicks in. They both sputter like they are going rich at that point and my only choice is to move to clip position 1 which I fear is a little lean as the bike is running hot but the sputtering stops.” Your bike is not behaving like I would expect. You have a very unusual setup with an LS400 cylinder head and a Wossner piston. Do you know what the valve sizes are? Are the valves in the 400cc head the same size as the valves in the 650cc head? You might possibly be struggling with a situation where your exhaust gasses are backing up at high rpm. That can cause the engine to misfire. It would run normally up to a point and then start to load up and misfire. Can you do another quick & dirty test to see if your baffle is the culprit. Don’t get carried away, just remove the pipe extension and try it to see if the misfire is gone. Lower gears only, don’t stretch it out. If it’s lean, going WOT in the higher gears could hurt it. If the valves in your 400 head are smaller than the valves in the 650 head, then the jetting requirements will be significantly different from a standard LS650 setup. What can you tell us about the valves in that 400 head? What size are the intake valves? What size are the exhaust valves? |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/01/23 at 13:21:11 Your baffle seems very restrictive. You mentioned there are a number of these plates over approximately a ten or twelve inch section of the pipe. The pipe ahead of the baffle has very little volume. There's no place for the hot exhaust gas to go. It just backs up in the pipe. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/01/23 at 13:24:25 Given the baffle location shown in your picture, the area upstream is pretty much the stock header. The inside diameter of the stock header is only 1.3". There isn't much room in there for all that exhaust gas. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/01/23 at 15:09:44 Mike, thanks for taking the time to look into my questions like that. I really appreciate it. What about the DGK led to it metering fuel at WOT? That's something I'd like to avoid. I'll just clarify the current situation. The issue isn't present at WOT. Sorry if my wording made it appear this way. It is present at 3/4 (maybe slightly past) while at higher revs. Currently im running the 140 main and 40 pilot. The bike is great to ride with either the DDJ or DGK needle. However, they both seem to be too rich at their final taper. This presents itself as great performance at WOT (no backfire or issues at WOT at all) and all through the rev range until just before the main jet takes over from the needle jet. At this point (and to be clear, I can deal with this issue and have fun riding regardless) it starts to break up and sputter, but the sputter stops if I increase or decrease the throttle. So to get this problem to appear on needle clip position 2, I have to hunt for it. Position 3 it's present over a wider section of the throttle range, 4 more so etc, with position 1 having it not present at all but being too lean all round. I messaged Sudco and got this response "The first letter is the taper angle, which affects more 1/2 - 3/4 throttle. The second letter is the L1 length which affects more 1/4 - 1/2 throttle, like clip position. The last letter is the straight portion diameter before the taper starts, which affects more 1/8 - 1/4 throttle. They overlap a little but that is where there primary affect. If you want a leaner taper than EGK then that would be DGK. If you wanted a leaner taper than DDJ, then that would be CDJ but we don't import that one, so there would be CCJ or CEJ. CCJ would be a half clip richer than CDJ and CEJ would be 1.5 clips leaner than CDJ. The PWK carburetors are designed for 2 strokes. 2 strokes require more fuel also require oil to go through the carburetor as well so the passages are larger than a 4 stroke carburetor. When people try to run the PWK on 4 strokes they have trouble getting them lean enough to function well in all circuits" |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/01/23 at 15:13:36 Regarding the valves on the 400 head, the part numbers are the same for almost the entire top end. Valves and springs etc are all the same part. I think my best bet, besides trying different needles which I am enjoying anyway as I'm learning, is to open up the exhaust a bit to help it flow better. I will make a new header and might even try removing the inner type from the stock one. I know this will be too big but it'll be a fun experiment. Perhaps I should do another test without the rear tail pipe to see if the problem ceases? |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/01/23 at 15:53:54 I just did a quick ride with the slip on tail pipe removed. Performance was slightly better over all and I couldn't find the 3/4 throttle stutter. Maybe the stock header and crappy tail pipe are the issue. I might try removing some of the baffles |
|
Title: Re: 12 USD Carburettor Post by LANCER on 08/01/23 at 16:00:07 In an ideal situation the volume inside the muffler should be the same as the volume inside the cylinder for best overall performance. Look at the mufflers that the factories have on their bikes, they have adequate volume. That is why the Dyna works so well on our engine, it has adequate volume. A straight pipe, with or without baffles, does not have the volume and it is chronically difficult to jet/tune well in all throttle ranges. Just like yours. If the carb you are using is designed for 2stroke engines then it would seem that it would have additional issues for you to solve. I’ve not used this type of carb so I’m not familiar with working out the issues. DBM is the person for that since he has history with this one. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/01/23 at 18:00:44 Thanks Lancer. The issue seems to be the restrictive pipe in my case. I think I will try removing part of the baffle and see how that goes. I really don't like the look of the dyna mufflers |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/01/23 at 19:22:43 I have ordered a cherry bomb style glass pack with and inlet and outlet ID of 44mm to slip on to the stock header. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/02/23 at 11:59:50 "The issue isn't present at WOT. Sorry if my wording made it appear this way. It is present at 3/4 (maybe slightly past) while at higher revs." "This presents itself as great performance at WOT (no backfire or issues at WOT at all) and all through the rev range until just before the main jet takes over from the needle jet. At this point (and to be clear, I can deal with this issue and have fun riding regardless) it starts to break up and sputter, but the sputter stops if I increase or decrease the throttle. So to get this problem to appear on needle clip position 2, I have to hunt for it. Position 3 it's present over a wider section of the throttle range, 4 more so etc, with position 1 having it not present at all but being too lean all round." Given that it takes WOT without any misfire, it seems unlikely that a restrictive exhaust is the culprit. If a restricted exhaust was causing the problem, the misfire would get progressively worse as you gave it more throttle. However, I do think a bona fide muffler will serve you better. "I just did a quick ride with the slip on tail pipe removed. Performance was slightly better over all and I couldn't find the 3/4 throttle stutter." So, once again your performance improves when you remove the pipe extension with the crazy baffle. You feel it's too rich at 3/4 throttle, but all other throttle positions are good. It's fine at WOT with a #140 main. All of that indicates that you could use a needle with less taper, but when you drop your current needle, you think it then goes lean in all the other throttle positions. It's the craziest problem. I'm baffled (sorry, I couldn't resist). Do you have a dial caliper? |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/02/23 at 12:11:52 "I think my best bet, besides trying different needles which I am enjoying anyway as I'm learning, is to open up the exhaust a bit to help it flow better." When you get to that cherry bomb, do a post with some pics before you install it. I would leave the head pipe alone. It will probably run better and be easier to tune with the smaller diameter head pipe. It's gonna be loud, but there are ways to tame it down and still maintain reasonable flow. I am gratified to hear that you are enjoying the tuning drill. You have been at it a long time. Glad you haven't given up on the beast. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/02/23 at 12:27:07 Lancer, these PWKs behave exactly like your VMs. They are a bit harder to dial in because the needle jet and main air bleed are fixed orifices, but they behave exactly like a VM. You wouldn't have any trouble dialing one in. IMO, the VM runs a bit cleaner, while the PWK makes a bit more power. The VM is a bit more flexible since there are so many readily available parts (needle jets in particular). Once dialed in, I really can't tell the difference. They run almost exactly the same (seat-of-da-pants). The only reason I started messing with the PWK was the challenge. I wanted to see if I could get one of these cheap knockoffs and make it work. Turned out to be easier than I anticipated. After I finish playing with the new PWK with the E-Tube, I want to revisit the old S&S super E. I have some ideas I want to try to see if I can iron out the rough spots. The S&S made lots of power at WOT, but it was a bit crude everywhere else. It was a hotrod. There's just nothin sweeter than having something totally different than everyone else, and also having it work good (like Versy's QuickSilver). |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/02/23 at 16:10:14 Thanks Mike. Given that it takes WOT without any misfire, it seems unlikely that a restrictive exhaust is the culprit. If a restricted exhaust was causing the problem, the misfire would get progressively worse as you gave it more throttle. Thats interesting. What do you think would cause it to be better without the baffled pipe if its not the issue? This is a pretty funky issue as it was better without the pipe. Maybe the pipe reaches a point of pressure where it cant quite force the exhaust through and when I go to WOT it moves out of that turbulent zone? I know the issue is tied to the needle but its interesting how the open exhaust fixes the issue. I guess with more flow it is just able to handle the extra fuel ? You feel it's too rich at 3/4 throttle, but all other throttle positions are good. It's fine at WOT with a #140 main. All of that indicates that you could use a needle with less taper, but when you drop your current needle, you think it then goes lean in all the other throttle positions. It's the craziest problem. Yeah it actually feels good over the whole range, except when at 3/4 in higher revs. Just a stutter/bog that goes away in pos 1. I feel like its too lean as the bike just gets hotter than usual. I can hear it creaking and clicking more than usual when I shut it off. So I just need a needle similar to the DDJ that has a little less on the final taper? I have a digital dial caliper that it terribly inaccurate. Ill buy a better reviewed one if I can find one that's not too expensive. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/03/23 at 10:14:19 You can use that dial caliper to do a comparison of the needles. I find that it helps me understand what's goin on with a particular needle, and it really helps when dealing with an unmarked needle. As long as the caliper is metal and the jaws/anvils are ground square, it works great. Set the caliper at a size that grabs the needle close to the bottom, then lock the caliper with the thumbscrew. Place the two needles in question side by side in the caliper. Like this. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/03/23 at 10:18:28 Then open up the caliper a few thousandths and place the needles side by side in the caliper. See how the needle on the right is running away from the needle on the left. The needle on the right is richer in that position. |
|
Title: Re: 12 USD Carburettor Post by DragBikeMike on 08/03/23 at 10:23:11 Then open the caliper up a few more thousandths. Check the needles again. The needle on the right is way richer. It's a good quick & dirty tool for comparing needles. The visual information helps me understand what I'm dealing with. The instrument is not nearly accurate enough to do a useful dimensional inspection of a single needle, but it's a great tool for comparing one needle to another, especially when one needle is marked and the other is unmarked. |
|
Title: Re: 12 USD Carburettor Post by Moarpower on 08/03/23 at 15:30:15 Ah, nifty trick Mike. Thanks. Ill do that today. |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |