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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Compression Project /cgi-bin/YaBB.pl?num=1567201633 Message started by DragBikeMike on 08/30/19 at 14:47:11 |
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Title: Compression Project Post by DragBikeMike on 08/30/19 at 14:47:11 The project I’m about to discuss is a bit over the top. It’s difficult and risky, but the results have been more than gratifying. There are still some bugs to work out, but I’m making progress. Some of you will think it’s a totally crazy approach, others may like the idea. Either way, it’s worth a look. I have a thirst for quench. If you Google search “cylinder head quench clearance”, you will find all sorts of experts advocating good, tight quench. It’s the clearance between the flat portion of the piston top and the flat bottom of the cylinder head (around the combustion chamber). As the piston nears TDC, fuel/air mixture trapped between the top of the piston and the cylinder head’s quench area squirts out at high velocity. This increases turbulence, which promotes better air/fuel atomization and reduces the potential for detonation. This is an illustration of a wedge combustion chamber. The S40 uses a pentroof. The concept is the same. Squeeze & squirt. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 14:48:51 You should be able to run significantly higher compression if your engine is set up with proper quench. Depending on the engine setup, optimum quench clearance is usually around .025” to .070”. I personally like .040” on a street engine. The Savage engine, for all intents and purposes, has no useful quench. That’s because the stock savage engine is set up with a deck height of minus .162” and a head gasket thickness of .028”, for a total of .190” between the flat portions of the head and the piston top (when the piston is at TDC). I present to you “The Problem”. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 14:51:12 Not only does our engine have a dismal 8.5:1 compression ratio, it also has no quench area because the piston never gets close enough to the cylinder head to create any useful turbulence. Some of you are running a Wiseco high compression piston. The Wiseco increases the compression by filling some of the combustion chamber with a pop-top dome, but the portions of the piston that overlap the flat surfaces of the head still remain a good .165” away at TDC. Result, no high velocity squirt. I’m not knocking the Wiseco. It is an inexpensive and easy way to amp up your compression. It just doesn’t create any quench, and I want some quench. I present to you “The Solution”. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 14:55:23 If you bring the flat top of the stock piston closer to the cylinder head at TDC, you accomplish two things. First, the obvious bump in compression ratio. Second, the quench area is tightened up significantly. Through direct measurement with a depth micrometer, I confirmed that on the stock engine the top of the piston at TDC sits exactly .162” below the top surface of the cylinder. This is the deck height. Combine this negative deck height with the thickness of the head gasket and you arrive at the stock quench clearance. To determine the compressed height of the head gasket, I clamped a used gasket between a set of torque plates and tightened the fasteners to 24 ft-lbs. The head gasket is .027” to .028” thick when compressed. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 14:57:25 So, the negative deck height of .162” combined with the head gasket thickness of .028” results in the piston being situated exactly .190” from the head at TDC. Since my favorite quench clearance is .040”, I would need to reduce the cylinder height by .150” to achieve my desired quench clearance. Another option would be to increase the piston compression height (distance from the centerline of the wrist pin to the flat top of the piston) by .150”. Both options have tall hurdles to clear. Lobbing .150” off the top of the cylinder requires machine tools and will result in the cam chain going loose as a goose. Also, it will retard cam timing, possibly cause interference problems between valves & piston, and create fit-up issues with the forward chain guide, dowels, etc. I have the machinery, correcting the cam timing is easy, resolving the fit-up issues is straight forward, but that loose cam chain might be a hard problem to solve. Installing a piston with an additional .150” compression height will require a special order (minimum purchase, ten pistons). Also, increasing the compression height affects the thrust action of the piston skirt which, IMO, would require engineering analysis (i.e. Wiseco engineering staff should be giving this modification a good look.) Piston thrust is affected by placement of the wrist pin, the length of the connecting rod, the stroke, angular velocity, etc. Way above my pay grade. I’m not willing to throw down a big wad of cash on ten special pistons (nine of which I don’t need), but I really want to see how this engine will perform with proper quench. I decided to satisfy my thirst for quench by lobbing off the top of the cylinder. If I can figure out a way to deal with the loose cam chain, maybe I can prove that the engine runs great with tight quench, and in the process conjure up some additional forum members who might be interested in the special piston. No guts no glory. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 14:58:30 The first thing to do is figure out what sort of compression ratio we can expect with the quench tightened to .040”, and then figure out the anticipated dynamic compression. I use the compression calculators at rbracing-rs.com. Their calculator for static compression ratio requires bore (3.703”), stroke (3.700”), combustion chamber volume (57cc), piston top volume (2cc, more on this later), head gasket thickness (.028”), and deck height (.040” quench - .028” gasket = .012” desired negative deck height). The static compression ratio worked out to 10.9:1 with .040” quench clearance. That’s kinda high for 92 octane pump gas in a 94mm bore. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:00:23 Their calculator for dynamic compression requires the static compression ratio (10.9), exact length of the connecting rod (centerline of rod bearing to centerline of wrist pin is 6.573”), intake valve closing point @ .050” lift (DR650 cam closes intake at 34 degrees ABDC, .050” lift), elevation above sea level (my garage is 650 feet), boost pressure (0), and the usual data on bore, stroke, etc. The dynamic compression calculator predicts cranking pressure will be 217 psi with static compression at 10.9. I think that’s gonna be too high. Maybe I can make do with .060” quench. Recalculating using .060” quench I get static CR 10.4:1 and cranking pressure predicted to be 205 psi. I would prefer around 190 psi but I also prefer .040” quench. It’s a compromise. So now, instead of lobbing .150” off the cylinder to achieve .040” quench, I will be lobbing off .130” to achieve .060” quench. That should be way better than .190” pseudo quench. Looks like I’m shooting for .060” quench, 10.4:1 compression ratio, 205 psi cranking pressure. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:02:09 Lobbing .130” from the cylinder top will bring the entire head .130” closer to the piston. At TDC, that could cause a problem with valve interference. I don’t want the valves clobbering the piston (or should I say the piston clobbering the valves?). Solution, cut valve reliefs into the top of the piston. The volume of the four valve reliefs was a total of 2cc. That value was used in the static compression ratio calculation. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:03:22 What about the cam chain? Way back when I was testing the Fastman’s (Fast650’s) HammerHead, I tried to figure out exactly what would happen if I lowered the head .125”. I made an eccentric bushing that would simulate a .125” drop in cam centerline. The bushing, when inserted into the cam sprocket and supported by a dummy camshaft, simulates the cam situated .125” lower, very close to how things would be if I lobbed .130” off the top of the cylinder. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:05:09 With the eccentric bushing installed things looked like this. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:06:40 And of course, the situation at the cam chain tensioner was dismal at best. Not only was the tensioner plunger extended to 27mm (very bad), but the drive & slack sides of the chain were dangerously close. Look at the chain just above the tensioner. This would have to be corrected. The Verslagy tensioner mod can only do so much. I’m fixin to drop this head another .005” from where this photo shows. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:08:40 The tensioner started out at 13.5mm. When I lowered the sprocket .125” the tensioner plunger extended another 13.5mm to a total of 27mm extension. So, we are lookin at about 2.7mm plunger extension for every .025” change in head elevation. Try to remember that number, it will come in handy later. I looked at using a cam chain with two less pins. The stock chain is 132 pins. A GSXR-1000 uses a chain with the same pitch & width and only 130 pins. With the eccentric bushing still in place, I tried installing an open chain with two less pins. It won’t go on, too tight. The shorter chain idea is a non-starter. Verslagen’s post in the tech section regarding his trick tensioner has a comment by a member named Aeres. It seems Aeres was able to take a bunch of slack out of his (or her) cam chain by bending the rear guide to increase the arc. I figured I might be able to increase the arc in the guide with an adjustable bolt. I call it a jack bolt. Turning clockwise would cause the jack bolt to push on the back side of the guide and force the upper portion of the guide to arc out into the chain. I gave the concept a try on the HammerHead. I spot faced the area on the cylinder head just behind the rear chain guide. Then drilled and tapped 3/8-NF threads. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:09:45 Then I installed a jack bolt such that it would push on the back of the tensioner when I screwed the jack bolt in. Note that the tensioner plunger that was extended 27mm is now extended only 13mm. The pawl is removed from the tensioner for test purposes. You can screw the jack bolt in and out and watch the tensioner plunger move. When the jack bolt is screwed in, the plunger retracts. When the jack bolt is screwed out, the plunger extends. It seemed to work good. |
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Title: Re: Compression Project Post by verslagen1 on 08/30/19 at 15:10:22 Yes, but you'll only get 2 small quench areas due to the 4 valve configuration. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:11:24 Here is a look at the jack bolt assembly installed on my Stage II head. In this photo the jack bolt is backed out all the way. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:12:17 In this photo the jack bolt is screwed in about 1/2”. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:14:30 When I experimented with this jack bolt idea, I was in the middle of preparing and installing my stage II head. I prepped the stage II head for the jack bolt too. Instead of a 3/8-NF jack bolt I set it up for a 5/16-NF and incorporated a steel threaded bushing in the aluminum head (for durability). But I wasn’t ready to try it yet, so I plugged the jack bolt hole and put the idea on the back burner. At that time, I was concerned about making the cam chain drive too rigid. Although the factory design seems to lock the tensioner in place, that long rear guide is still flexible. Once I put that jack bolt in there, the rear guide becomes rigid. So, when the cylinder grows, the pawl restrains the bottom, the jack bolt restrains the middle, and the pivot bolt restrains the top. It’s not gonna give much. We already have a problem with accelerated chain wear. I wasn’t willing to solidify the system. Later, I start seeing discussion on the forum about Batman’s complete removal of the tensioner pawl, and then Dave sets his up with no pawl and a stopper to restrict plunger retraction to 1mm. While I understand that Batman’s system is working fine, I need more control over my valvetrain. The unrestrained plunger setup is fine for a daily driver, but I’m pushing mine past 6.5K on a regular basis, and I’m fixin to bring the valves a whole lot closer to the piston. With the pawl removed, you can watch that plunger stroke in and out a bunch as the engine rotates. Every time the intake lobe goes past the nose, the valve springs take control and drive the cam. That takes the slack out of the rear side of the chain. The pawl is there to prevent the cam from running away. The cam lobe has a deceleration ramp that is intended to gently place the valve on the seat. The deceleration ramp can’t perform its intended function if the rear side of the chain is slack. The chain must hold back the cam as the intake valve is closing. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:16:45 This photo shows how much that plunger moves when the pawl is removed. I coated the plunger with grease and rotated the crank in the direction of rotation five or six turns. The grease line tells the story. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:18:09 Dave’s setup (no pawl, stop to limit back travel) limits the slack on the rear side of the chain. I can use a tensioner with the pawl removed, incorporate a stop to limit plunger retraction, and install the jack bolt to take up the majority of the excess slack. Instead of extending the front side of the tensioner plunger (like Verslagen), I extended the back side 15mm. That provides additional engagement with the tensioner bore to keep the plunger straight and prevent cocking. I left off the rack for the pawl (I could never machine that) so the plunger has a nice close fit completely around it’s circumference. It’s very stable. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:19:06 Then, 7mm washers were used to act as a stop. With the jack bolt adjusted so that the plunger extends 18mm, two washers limit back travel to 1.5mm. Some time ago, I did a post on cylinder expansion. I measured growth at exactly .025” from ambient to normal operating temperature. I know from the eccentric bushing measurements that the plunger extends or retracts 2.7mm for every .025” change in cylinder height. The rate of expansion for aluminum is roughly twice that of steel. So, when the cylinder grows .025” the chain is growing about .012 (each side). The plunger should retract about half of 2.7 mm from ambient to normal operating temperature. The 1.5mm back travel limit provides a little grace. We shall see how it works out. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:20:38 Here’s the finished tensioner installation with jack bolt adjusted for 18mm plunger extension. Almost all the plunger shaft is engaged with the tensioner housing. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:22:02 Periodically, I will inspect the plunger extension, and if necessary, adjust the jack bolt to restore the extension to 18mm. It will become part of my routine maintenance. Now there is the issue of cam timing. Awhile back, Armen gave us the lowdown on indexing the drive sprocket on the crankshaft. There are more splines on the crank than teeth on the sprocket. That means that you can move the sprocket one-spline, but it does not change the position one-tooth. So, I advanced the sprocket one spline on the crank and it dialed in my cam timing perfectly. Talk about a lucky break. A BIG mahalo to you Armen. Here's a look at what advancing the sprocket looks like. Notice the dots on the sprocket and the end of the crank shaft. Also note the cleanliness plug stuffed in the opening to the engine sump. You don’t wanna be workin in here without that cleanliness plug. I’m guilty of violating this commonsense rule. I gotta try harder. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:26:13 It looks like all the big problems have been addressed. Lob off the cylinder .130” to reduce quench to .060” and increase CR to 10.4:1. Provide adequate clearance between valves and piston by machining valve reliefs .130” deep in the top of the piston. Remove excess slack from the cam chain using the special jack bolt and extended tensioner plunger. Correct cam timing by advancing the drive gear one-spline. Machining that cylinder was quite a project on my teeny-weeny Chinese lathe. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:28:26 Cutting the valve reliefs was a lot easier than cutting the cylinder. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:31:03 When all the machining was done, it had to be assembled with gaskets and torqued to spec in order to verify correct quench. Quench was checked by laying feeler gages on top of the piston and then laying a strip of lead wire on the feelers. Rotate the engine through several times, remove the head, and measure the thickness of the crushed lead wire and feelers. The total thickness of the feelers and lead wire was .0595”. Close enough. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:33:21 The front chain guide had to be trimmed to make sure it didn’t interfere with the cylinder head. The T-shaped tabs and shoulder had to be filed back such that they no longer protruded above the gasket surface. It’s easy. The material is a hard rubber and easily worn away with a file. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:35:55 Prior to machining the cylinder deck, the oil feed groove for the cylinder head must be made deeper. The stock groove is only about 1/8” deep. Since I was removing slightly over 1/8”, the groove would be eliminated. I used a die grinder to make the groove ¼” deep. That way, once I was finished machining the deck, the remaining groove would be about 1/8” deep. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:38:31 To make sure that the two dowels that locate the cylinder head don’t interfere with the head, I shortened each dowel 1/8”. I made sure that the head would go all the way home, even without a gasket. It’s always good practice to verify that nothing is gonna hit when the engine is all back together. Use modeling clay to check for ample valve-to-piston clearance. Place clay on the piston in way of each valve relief. Apply a liberal coat of grease to each valve so the clay doesn’t stick to the valves. Assemble the engine completely, torque the head and adjust the valves. Then rotate the engine through (at least four revolutions). Do not force it. Rotate gently. If it gets hard to turn something is probably hitting. Investigate. Disassemble and measure the clay to determine clearance. I use a small drill bit with a piece of aerosol spray tubing. Verify vertical and radial clearance (minimum .080” intake & .100” exhaust). This setup had about .140” vertical on the exhaust valves and the intake valves don’t even touch the clay (so much for valve reliefs). BTW, used head gaskets come in handy for these checks. New gaskets cost about $40 a copy so save an old gasket for clearance checks. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:39:22 You stick the bit down through the clay until it hits the aluminum, then gently run the plastic tube down until it just touches the clay. Pull the assembly out without disturbing the tubing. Now you can measure how thick the clay is. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:40:53 So now it’s time to put it all together for real. All the clearances check out. I won’t go into all the gory details about honing the cylinder, checking ring gaps, etc. Let’s just say put it together in accordance with the manual and good shop practice. As I stated earlier, I set up the tensioner jack bolt so that the tensioner plunger extended 18mm. Each time I inspect the tensioner, I will adjust as necessary to bring the plunger back to 18mm. If the drive and slack sides of the chain start getting too close to each other, I will install a new chain, rear guide, or both. Only time will tell how well it holds up. To lock the jack bolt in place, I fabricated a jack bolt lock cap. It uses an o-ring to keep the oil in the engine. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:42:26 Given how ugly things could get if the jack bolt came loose, the lock cap must be secured. Safety wire is mandatory. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:43:16 Once the engine was all back together and installed in the frame, it was time for a very important check. Before I removed the engine, I checked compression. It was 175 psi. I’m hoping that now the compression does not exceed 195 psi, but I machined a lot of material off that cylinder. The rbracing calculator predicted it should come in around 205 psi. It was time to find out. Oh no! That sucker pumped out 245 psi. Now what? That is an awful lot of squeeze for 92 octane E10. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:45:23 Time to make a decision. I can take the engine back out, disassemble, and machine a pocket in the top of the piston to lower the compression. That’s a lot of work. But there’s only a small amount of work remaining to put the bike back in operating condition. Why not try it and see what it does? If it detonates, stop and add fuel and/or pull out ignition timing. If it still detonates, remove the engine and machine the piston. At least I can find out if it will run with the new cam chain tensioner system. It started right up. No problem cranking it over. I did a 500-mile break-in with 10W-40 mineral based oil. The first 100 miles was total kid gloves. Never took it past 4K. Never gave it more than ¼ throttle. The next 200 miles was a bit more aggressive. Maybe as much as ½ throttle. Kept it below 5K. The last 200 miles was normal driving except for no WOT. Throughout the break-in I continually accelerated and decelerated. Tried not to run at a steady speed. It ran just fine. Absolutely no hint of the dreaded spark-knock, ping, rattle, etc. I was mystified. It felt frisky. The increased compression and .060” quench really cleaned up the carburetion. It idles better. Throttle response is very quick. It really raps when you blip it in neutral. It’s way torquier. It’s a blast to pass on two-lane roads. Clearly more powerful. There’s noise, not loud noise, not necessarily bad noise, different noise. It’s hard to explain. The tappets sound about the same, click, click, clicking away, but there’s also an unusual resonance, whir, hum sort of sound. It doesn’t sound like anything is eating itself up. No grinding or scraping sound. But it is different. After logging 500 easy miles it was time for an oil change and visual inspection. I dumped the dino oil and popped off the clutch cover. The oil looked fine. No chunks of rubber or metal. I poured it through a fine mesh wire strainer. All I caught were a few pieces of hardened Loctite. I stirred it up with my shop magnet. Just picked up a few small bits of metal typical of what you would expect from an engine that shares oil with a crash-box transmission. The tensioner plunger was at 19mm extension. Not too bad. I figure there had to be a fair amount of bedding in since new areas of the rear guide are bearing on the chain. I can live with 1mm increased extension for now. I pulled the rear chain guide. It had a few areas where it showed impressions and rub marks from the chain. It looked like a typical cam chain guide. No evidence of failure. The spark plug showed no signs of detonation. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:46:19 Here’s a picture of the current rear guide next to a new one. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:47:06 This is what the wire strainer caught. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:47:50 Here’s what the plug looked like. Not seeing anything that would hint at detonation. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:49:58 It was good to go WOT. I strapped on the GoPro and headed out. It ran great on my way to the test area. I gave it WOT every chance I got and there was still no hint of detonation. Rolling it on in 5th gear felt amazing. It simply has torque everywhere, and acceleration is strong. Got to the test area and started doing 2nd gear WOT pulls, recording each pull on the GoPro. On the 4th pull I thought I might have heard a rattle. On the 5th pull I heard it again as the tach flew past 5K. It seemed to be detonating so I discontinued the test. On the way home it ran just fine. I pulled the spark plug and there was no evidence of detonation. I inspected the piston through the spark plug hole using a flexible camera. The piston looked fine. Review of the videos confirmed my seat-o-da-pants impression. This thing is a lot faster. The 2nd gear 4K to 7K time is now 2.89 seconds. That’s .73 seconds faster than the baseline I established with the Stage II head and stock carburetor, and .56 seconds faster than the stage II head with Super E carburetor. Consider that the .56 second improvement is only for second gear. There are five gears. There is an improvement in every gear so a WOT trip through the full gearset is gratifying. Just need to address the detonation issue. If what I think I’m hearing is in fact detonation, I must eliminate it. If it’s something else, or my imagination, I have to figure it out and put the issue to bed. IMO, if it was detonating it should have left some telltale indicators on the spark plug or piston, but those components look fine. I also figure, that it should rattle when I load it up in 5th gear, but it doesn’t. I couldn’t hear any rattling when I reviewed the vids. I went through them with the volume at max. No rattle. First order of business was to add more fuel. I upped the main jet two sizes from a 62 to a 66. Took it for a short ride to see how it ran. It felt good, but I could swear I heard a rattle when I took it WOT in 1st gear. It was getting late, so I put it to bed for the evening. I was going to take it for a vid run in the morning. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:51:25 The next morning, I threw in a colder plug (DPR9EA-R). I went to roll it out of the garage, and I couldn’t move it. The rear tire was flat as a pancake. There was a steel rod stuck clean through my old worn out tire. Oh well. It will be a good two weeks before I can get a new tire and tube out here. Lucky I didn’t get stuck out in the boondocks. What a drag. Two weeks downtime, minimum. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:53:24 In the meantime, I plan on installing a wide band Air Fuel meter system and pulling 2° to 4° out of the ignition timing. Any of you play with that ignition pickup? How did you do it and how did it work? Once I’m back on the road, I will continue testing, add fuel as indicated, and see how it goes. The BIG question: is it really detonation or is it paranoia? If I can’t find any concrete signs of detonation like balls of metal on the plug, cracked plug insulator, or sand blast texture on the piston, I’m not so sure its detonation. The contraption has always been a bit of a rattletrap. Maybe it’s just the normal Savage cacophony. The 245-psi cranking pressure has me freaked out. I might have target fixation. For now, I have learned a few things. It looks like the problems associated with dropping the head .130” can be managed. You may end up with an engine with reduced life expectancy, but hotrods have never been models of economy. If you wanna play you gotta pay. Only way to answer this question is to keep runnin it and see how it holds up. 10.4:1 compression ratio makes some real good power, and that 245-psi cranking pressure seems to work out reasonably well with the Savage combustion chamber and .060” quench. Under normal everyday driving conditions, it’s superb. WOT is killer fast (hopefully not in the literal sense). Dave has mentioned a number of times that the S40 responds well to an increase in compression. That is an understatement. This thing loves more squeeze. I am amazed that it can handle 245 psi on 92 octane. The little starter can still whip the motor over smartly, even with over-the-top cranking pressure and no flywheel. Looks to me like there’s a lot of potential in a flat top Wiseco with .130” additional compression height. If it turns out that I do have a detonation issue, the Wiseco could always be manufactured with a slight dish in the top to bring the cranking pressure down 20 to 30 psi. Still need to find out if skirt thrust will be a problem if the compression height is raised about 3mm. More to come. I’ll keep testing and adjusting as necessary, and periodically post updates. |
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Title: Re: Compression Project Post by DragBikeMike on 08/30/19 at 15:54:45 I want to thank the Fastman (Fast650) for holding my hand through the process. He was my sounding board and offered great encouragement and advice throughout the project. It’s always great to have someone to run your ideas by. Thanks to Batman for taking the bold step of pulling the pawl out of his tensioner. It proved that you can run the thing with the chain unrestrained, and that helped formulate the basis for my tensioner plunger setup. Thanks to Dave for sharing the details on his modified tensioner with me. It helped me arrive at the value for setting the stop. Thanks to Verslagen for all his hard work on the Verslagy tensioner. Groundbreaking, to say the least. Reading all the posts on that setup gave me all sorts of ideas on how to deal with the loose chain, and good insight as to just how far you can let it go. Thanks to Armen for his chain sprocket indexing trick. It worked like a champ and allowed dialing in the cam timing to the gnats-behind. I hope some of you find this report interesting and useful. If you have any suggestions or personal insight LMK. Knowledge is power. |
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Title: Re: Compression Project Post by verslagen1 on 08/30/19 at 16:26:53 484E413D3F383C0C0 wrote:
0C2D160567490 wrote:
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Title: Re: Compression Project Post by jcstokes on 08/31/19 at 01:06:48 Pardon my ignorance, but did you machine 130 thou off the block/barrel? |
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Title: Re: Compression Project Post by LANCER on 08/31/19 at 04:54:11 Years ago when my engine died due to a puncture on the bottom of the case, I had the original Stage 1 cam made/installed and also had the head shaved 25 thou. (.025") and the cylinder shaved 15 thou. (.015") The numbers may have been reversed, 15 thou (.015") head and 25 thou (.025") cylinder, memory is a bit foggy. Also required was a slight bore of 94.5mm due to some scraping, and it received the silicone carbide treatment. It ran great, no issues at all. I don’t remember the cylinder cranking pressure but it seems like it was about 185-190. Everything else within the engine remained stock. Can you offer a general comparison between what you have done and the little I did back then ? You are taking a whole lot more off than I did. |
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Title: Re: Compression Project Post by Armen on 08/31/19 at 07:05:00 Hey DBM, As usual for you, outstanding work! You basically did what I was thinking about doing on mine. One quick hint-When you are checking valve-to-piston clearance, assemble the head with very soft springs. Set the valve clearance as usual. Rotate the motor slowly while holding the rocker arm pushing down on the valve. When you feel the rocker lifting up, slow down. Rotate slowly til you feel the rocker at it's highest point (piston pushing up the valve). Stop pushing down on the rocker. Stuff progressively larger feeler gauges between the rocker tip and the valve stem until you determine the amount of clearance you have between the valve and piston crown. Did I read correctly that you are going to retard the timing? Tighter squish should mean more turbulence should mean faster flame travel should need less advance. So, less is good. thanks again! Any plans for a dyno run? |
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Title: Re: Compression Project Post by DragBikeMike on 08/31/19 at 13:52:38 Regarding Versy's comment: "Yes, but you'll only get 2 small quench areas due to the 4 valve configuration." I would like more quench area, but it is what it is. IMO, if you combine the quench area on the intake side and the quench area on the exhaust side, it looks about equivalent to a Harley Evolution cylinder head's quench area. It's certainly better than no quench at all. I've been looking at a lot of sport bike engines at my buddy's independent shop. They all seem to be set up with zero deck and .028" head gaskets. They all also have pentroof combustion chambers. Seems to me the factory did that for a reason. I don't know if I will ever figure out whether or not the improvement in performance was worth all the effort, but I certainly am learning a lot. From the learning perspective, its worth it. BTW, thanks for the info on the pickup Versy. Here's a pic of the quench area. Its the area marked in red. |
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Title: Re: Compression Project Post by DragBikeMike on 08/31/19 at 14:00:55 JCStokes, yes, I machined .130" off the top of the cylinder. I was on the fence for awhile trying to decide whether or not to remove the material from the top or the bottom. Taking it off the bottom is a bit harder because you have to stop the cut right at the cylinder liner. It also is a bit more critical to maintain perpendicularity so you don't end up tipping the cylinder to the right or left. Taking it off the top is easier to machine but there's that pesky oil feed groove to worry about. In the end, the design made it easier to decide. Seems there is a flange in the bottom of the liner that locks the liner in-place. I had no idea how thick the flange is and didn't want to risk lobbing it off, so I took the material off the top. Here is a shot of the flange in question. |
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Title: Re: Compression Project Post by justin_o_guy2 on 08/31/19 at 14:04:05 Do we need to take up a collection for you to get a flipping pencil sharpener? |
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Title: Re: Compression Project Post by DragBikeMike on 08/31/19 at 14:06:22 Here is a shot that shows the new cylinder deck after machining. You can see there is no longer a raised flange, its now flush with the top cooling fin. |
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Title: Re: Compression Project Post by DragBikeMike on 08/31/19 at 14:17:21 Lancer, thanks for sharing those numbers along with some historical info on your mod. Looks to me like you reduced the cylinder head height about .040". You also had a slightly larger bore. Both affect CR. I'm gonna try and plug the appropriate numbers into the calculator to see what the static CR was. The dynamic CR is dependent on intake valve closing. If my memory serves me correctly, Dave was kind enough to loan me a Stage I for timing checks. If that's the case, I should be able to see what the calculator predicts for cranking pressure. I'm comfy with the calculator results on static CR, that's straight forward number crunching. But the dynamic calculator didn't predict my cranking pressure worth a darn. It will be interesting to see the results. I might add, when I used the calculator for a stock Savage engine, it predicted 8.2:1 CR and 152 psi cranking pressure. That's very close. I have no clue why it was so far off on this modification I am in the middle of. |
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Title: Re: Compression Project Post by jcstokes on 08/31/19 at 14:19:28 Jesus, 130thou is over 1/8 inch, will this affect flow/ quantity in the oil groove, and what does the oil grove feed? |
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Title: Re: Compression Project Post by DragBikeMike on 08/31/19 at 14:37:21 Hey Armen, I'm flattered that you and I were on the same wave length. How were you planning to deal with the slack cam chain? Great tip on checking for adequate valve-to-piston clearance. I normally use checking springs, but in this case I was simply too lazy. I already knew the TDC lift numbers, and scooping out .130" valve reliefs made me pretty close to positive that there would be loads of clearance. I use the soft springs to make it easier to bar the engine through and provide better feel in the event of contact. Your method is way cooler. I'm likin it. As far as the dyno is concerned, yes, I want to get it on a dyno. Those are few & far between out here, and since they closed down our race track in 2006, there's not a whole lot of demand for dyno time. My last attempt was a disaster and wasted a bunch of my time. That's why I am now doing videos of the tach during testing, and then timing acceleration from 4K to 7K. The video record along with the A/F meter work excellent for test & tune. Not perfect but it certainly gives a good indication if things are better or worse. I'm very satisfied with the performance results on this project. But there's just nothin like havin an actual horsepower & torque curve. I'm workin on it. I've been meaning to retard timing on this thing for awhile now. Would be nice if there was a way to adjust it without tearing everything apart. I agree, taking some advance out should be beneficial with the increased squeeze and tighter quench. I'm thinkin if I have to retard more than 4 degrees it would be better to tear it down and dish the piston. What do you think? BTW, your loan of your chopped up head got me started on this crazy project. Thanks again. Then, The Fastman fixed me up with the HammerHead and it's been Nirvana ever since. These old beat-up parts serve as fabulous test beds for ideas. Don't throw em away. |
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Title: Re: Compression Project Post by Armen on 08/31/19 at 21:37:18 What is total advance now? Seems a really happy motor runs about 28 degrees total advance. Can't think of any that did less. Lots of crappy combustion chambers ran a lot more. Most welcome for the loan of the jigsaw head. I honestly didn't think it would be .130" cut. Judging by the numbers being thrown around, I knew the bike had zippola squish. As far as I got was to think about extending the tensioner, and putting a piece of steel rod in the center of the spring to limit the amount of travel back into the tensioner. Was going to put a window in the side of the cylinder so I could check tension cold and hot and come up with an ideal cold chain tension. Got seriously sidetracked on my project. Just this past week I finally got back to it. Did the double-wide sprocket bearing and the modified axle spacer. Removed a bit of the exhaust donut. Then I spent a ton of time on the side stand (modified 675 Triumph). Then the muffler bracket. And........ |
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Title: Re: Compression Project Post by Dave on 09/01/19 at 04:28:13 I go away for a few days.......and DBM is turning the Savage world upside down! :-? I also noticed that the sound of my engine changed considerably when I put the 95mm Wiseco in. The additional compression seems to make the power pulses more pronounced and this extra power resonates out of the engine when you are using that power. If the Wiseco were to be modified I am not sure the actual deck height would be changed much.....the top of the piston had a relief cut all the way around the top OD of the piston - improvement might be as simple as eliminating the relief. Good work DBM! |
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Title: Re: Compression Project Post by batman on 09/01/19 at 08:11:12 Mike ,If the problem is to high of a compression ratio , rather than retarding ignition timing , or machining the piston dome , due to your static compression being 245 psi , I would backup a bit and remove the advance in cam timing. the exhaust valve's early opening may have something to due with the strange noise your hearing , higher chamber pressure still has to find it's way out of the head through the same size valve seat. the intake valve's earlier closing has also boosted your CR ,something I didn't see taken into account in the compression formula you used that arrived at 215psi . You could also drop CR AND increase the effectiveness of the quench you've created by the use of Singh grooves. the loss of compression might be made up by the increase of combustion efficiency . As far as I know ignition timing advance stops a about 5000rpm, the fact that your getting 7000 rpm out of second gear (500 rpm over redline) hints the ignition is pretty forgiving ( and fast with the sparkplug centered in the head) .I really don't see that retarding it farther would be necessary, or that you would see a perceptive change. A 2-4 degree change might be negated simply by changes in elevation.(but may show slight improvement as you get closer to sea level). |
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Title: Re: Compression Project Post by DragBikeMike on 09/01/19 at 16:56:12 Armen, that quest for a featherweight is a never ending battle. I admire your tenacity. If you folks haven't seen any pics of Armen's masterpiece, I suggest you lobby hard for a look see. It belongs in the Guggenheim. Regarding ignition advance curve: The factory service manual lists advance on the original Savage as 5 degrees BTDC before 2000 rpm, and 30 degrees BTDC after 4000 rpm. Then, in 1988 that spec was changed to 5 degrees +/- 2 degrees BTDC below 2000 rpm, and 30 degrees +/- 2 degrees BTDC above 4000 rpm. This spec remained unchanged until 2003. Then from 2004 to present, the spec is listed as 5 degrees BTDC at 1100 rpm. Data I took and posted back in April of 2018 showed that my 2016 LS650 (stock at that time) was running 3 degrees at idle and 27 degrees fully advanced. This old post gives the lowdown on that test. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1521968829 So Armen, your 28 degree threshold might be right on. But alas, I must try. I used to run 25 degrees on my hotrod Harley, but that was with a power adder. Virtually everything I have read and am currently reading suggests that you pull out timing when you jack up compression. That's not intended for protection. Its for the exact reason you gave, the charge is more turbulent and homogeneous so it burns a lot faster. Hence, you need to light it off a bit later. We are in total agreement. |
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Title: Re: Compression Project Post by DragBikeMike on 09/01/19 at 17:11:38 Lancer, I took a look at the scenario you described. Milling .025" didn't tighten up the quench but did reduce combustion chamber volume. Taking .015" off the cylinder tightened the pseudo quench a bit (reduced it to .175"), but IMO not enough to improve combustion any appreciable amount. I had to make an assumption regarding your finished combustion chamber volume. I assumed that milling .025" off the head surface would be approximately equivalent to 70% of a reduction in volume due to reducing cylinder height by .025". So I figured out the volume of a 3.700" cylinder .025" tall and took 70% of that. It worked out to 3cc. I reduced combustion chamber volume from 57cc to 54cc and plugged all the numbers into the rbracing calculator. The result was a static compression ratio of 8.73:1. Then I used that value, along with an intake closing point of 40 degrees ABDC @ .050" lift (data from Dave's Stage I), and an elevation of 652 feet (based on your location) and plugged that data into the dynamic calculator. That predicted a cranking pressure of 157 psi. Like I mentioned earlier, I'm comfy with the static calculator, but the dynamic I'm not so sure for our application. It's a Harley specific calculator so there might be induced errors when applied to a metric cruiser. What sort of performance gain did you experience with that setup? BTW, how did you puncture your crankcase? |
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Title: Re: Compression Project Post by DragBikeMike on 09/01/19 at 17:24:30 Dave, I agree the bump in CR makes a distinct change in the exhaust note. Mine went from a muted thud, thud, thud to a muted pop, pop, pop. It sounds healthier, but I certainly wouldn't say pleasant, or muscular. Let's face it, this ain't no V-Twin. My muffler is also very quiet. The raised top of the Wiseco is .060" above the flat top of the piston. In addition, the flat top of the Wiseco is .025" taller that the stock piston. So if the Wiseco were simply manufactured with the entire top flat as you suggest, it would reduce the quench clearance by .085". That would give us .105" quench clearance. I didn't run the numbers on that but I intend to. No doubt it will raise the CR and the cranking pressure, but I'm not sure we would realize much additional turbulence. One benefit of having the top flat is there is nothing to impede flame travel. I don't think the current Wiseco impedes flame travel, but if the pop top were tall enough to protrude into the combustion pocket in the head it would tend to trap unburned charge in the areas that surround the combustion chamber (the pseudo quench zone). I took the measurement on the pop top with a cheap depth mic but I think it should be good within a couple thousandths. |
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Title: Re: Compression Project Post by DragBikeMike on 09/01/19 at 17:26:27 This shot shows the Wiseco and the stock piston sharing the same wrist pin. If you look close, you can see the flat top portion of the Wiseco just slightly higher than the stocker. |
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Title: Re: Compression Project Post by DragBikeMike on 09/01/19 at 17:28:14 In this shot, the pistons are still sharing the same wrist pin. When I lay the .025" feeler on the stocker, there is no discernable step between the two pistons. |
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Title: Re: Compression Project Post by DragBikeMike on 09/01/19 at 17:54:07 Batman, I originally planned on using the cam retard trick if this thing posed a compression issue. I've used it in the past and it can provide some relief under the right set of circumstances. I figured if there was too much compression I would experience the classic symptoms, hard starting and knocking when I lugged the engine. Closing the intake later starts the effective stroke later. That makes the engine easier to crank and tends to eliminate detonation when lugging the engine at low speed. That's not the case with this engine. I'm not even sure if it actually is detonating. I simply don't have any experience with cranking pressure this high running on pump gas. It starts right up and I don't get any audible indication of knocking doing day-to-day street cruising. There's no visible indicators either, like ugly spark plugs or sand-blasted piston tops. All seems normal. The only time I think I might be hearing any bad noise is at high rpm. Under that condition, the retarded cam timing will enhance inertia filling and bring the pressure up rather than bleeding it off. For now, I'm going to leave cam timing set right on the factory marks. I'm not sure about Singh grooves. I really don't get the concept. I viewed one of his infomercials on throttle bodies but it just didn't seem logical. Maybe I missed something. You've mentioned that you incorporated those grooves into your engine/carburetor. Do you have any pictures you can share so we can get a better idea about what they look like, where they go, how to cut them, angles, depths, etc. My primary reason for pulling out timing is performance. I think it will make more power with less ignition advance. If that provides a little more margin for preventing detonation, bonus. It also gives me the opportunity to play with that ignition pickup and figure out a good way to move it around. It would be great if the system had a vacuum retard like a Harley. |
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Title: Re: Compression Project Post by LANCER on 09/02/19 at 05:05:50 Performance with the setup as described above ? -94.5mm piston, stock CR -Stage 1 cam -good flowing muffler, memory is fuzzy on stock or 1.75” OD header I had a 4.9 sec. 0-60 and a 12.1 sec. with a speed of the high 80’s in the 1/4 mi., from a standing start. That is the only hard data I had. This was about 12 years ago. It ran very well, easy start, smooth idle, no hiccups going to wide open, acceleration was quick, had to lean over the bars to keep the front wheel down on launch. The standing start launch hampered the times a bit because of that. After spending 30 minutes doing these runs I decided I needed to beef up the clutch so installed HD springs later. On the road it felt like getting out of a VW Bug and into a small sports car. Noticeably quicker with a little extra top speed. Passing on the highway was made easy. It was a blast to ride. |
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Title: Re: Compression Project Post by batman on 09/02/19 at 09:11:11 Mike I talked about the Singh groves ,but I''ve never had my motor torn down ,it remains stock . I did use the Gagetman groove in the stock CV carb I run , That groove is just in front of the throttle plate , at idle and low throttle setting the fuel slides down the plate hits the grove and is deflected up into the center of the intake passage ,finely atomized . saving fuel at idle, (mpg increased by 3.5 ) and allows me to run down to 40 mph in 5th gear with no hesitation when accelerating . The use of the Singh groves have a few benefits , Suzuki's claim of a TSCC ,I find doubtful , Intake velocity drops to zero as the piston approaches TDC , and the intake valve closes at 11 degrees before TDC, and the cam has no overlap. How much swirl does it provide then? just when you need it most for better ignition probability. The Singh groves provide added turbulence as the piston rises to TDC ,and provides a path for the flame front to enter the quench zone for complete burning, (something you were concerned about and I would be too -not a good place for carbon build up). the grooves start at the back of the qench zone and proceed to the front at a 4 degree angle , start with a hacksaw blade , and finish the groove V shaped with a knife blade file ,rounding the edges at the surface slightly (to avoid carbon buildup. ) the amount of material removed will decrease your CR ,you'll have to cc the head to know how much . the other benefits of the grooves are with more complete combustion comes better mpg and reduced head temperatures in spite of you higher CR. You way think Singh is a wako ,but he has a US patient. Ford motor company filed a patient for a similar device 6 months later.The Singh grooves show there best performance in mid rpm but that's where the bike runs most of the time. IF I ever get into my motor I'll be employing them,but I'm the jerk who tossed his tensioner paw away 19000 miles ago! |
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Title: Re: Compression Project Post by justin_o_guy2 on 09/02/19 at 11:13:49 Makes me wonder why it exists. Except for the fact that it sends bikes to the graveyard, in to shops, and sells chains.. Are we supposed to believe the factory never even tested the idea of no pawl? Gutsy move, and really, Frikken smart, which is kinda rare for jerks. |
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Title: Re: Compression Project Post by Armen on 09/02/19 at 11:53:01 Batman, Are you sure about your numbers??? Intake open til 11 degrees BTDC? Maybe 11 degrees after BDC? Can't imagine any engine having a piston coming up on an open intake valve. |
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Title: Re: Compression Project Post by batman on 09/02/19 at 12:13:51 No wrong numbers ,my best guess is 26 degrees before TDC for the intake to be closed . And yes the valve is open as the piston rises that's why the torque peak doesn't occur until 3400rpm. the cylinder doesn't fill because the piston pushes the fuel air mix back into the intake passage. |
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Title: Re: Compression Project Post by DragBikeMike on 09/02/19 at 14:58:28 Wow Lancer, 12.1 quarter mile. That's sweet. Was that at the dragstrip or did you use some sort of performance analyzer? What carburetor were you running with that setup? I was hoping you would share how you punctured the engine case. Its always good to know the lowdown on failures like that. Batman, do you have any pictures or sketches of the groove in your carburetor. Regarding the groove you are describing, I assume its in the piston. Do you have a sketch, or a link to the website. Regarding cam timing. Using the tried & true direct measurement method, the stock cam puts the intake valve on the deceleration ramp at 70 degrees after BDC. At that point, it is only open .015". From there, it gradually places the valve on the seat, and the valve is on the seat at 70 degrees before TDC. For all intents & purposes, there really isn't anything flowing through the intake valve once it enters deceleration at 70 degrees ABC. |
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Title: Re: Compression Project Post by batman on 09/02/19 at 15:52:53 OK I'm all wet ! on the numbers but there's still 70 degrees of piston moving upward from BDC while the intake is open .the pressure building in the cylinder only has to over come the pressure of the intake (14.7 psi) before some is pushed back. |
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Title: Re: Compression Project Post by LANCER on 09/02/19 at 16:06:51 Case damage was done on I-26 in SC. Size/shape just like the top of a piggy bank, a narrow slit the size of a 50 cent piece; squared corners and all. Strange. Never found what hit it. Metal-metal screeching sounds and then seizure. It did restart 40 min later and limped to get me home then pulled the engine. Hole was welded. You can still see the scar. Did the runs on a flat 2 lane country road. Did runs both ways alternating. Was running the stock carb, jetted, with a Dail-a-jet. Hi, and the slide had been drilled a bit, the two holes on the bottom. I had the Veypor computer mounted on the bike. The data gathered from that gives immediate time, speed and exact distance traveled, with an acceleratorometer to detect the instant movement is detected. Then all data is down loaded into a computer program that provided second by second hp, Torque, rpm, and a dozen or more others. Anyway, it worked. With stock gearing and some added perkiness it had a real tendency to jump off the line. I don’t care for wheel spin, it eats rubber and slows times |
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Title: Re: Compression Project Post by batman on 09/03/19 at 06:23:29 Mike , sorry I forgot to say that the grooves aren't placed in the piston ,they're in the major quench areas of the head .directly between each set of valves ,only two grooves for our 4 valve head . pointing at the sparkplug. Sommender Singh grooves is all over the web with pics |
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Title: Re: Compression Project Post by ohiomoto on 09/03/19 at 07:07:02 https://somender-singh.com/ http://https://www.hotrodders.com/forum/attachment.php?attachmentid=48246&stc=1 http://www.mtfca.com/discus/messages/331880/363115.jpg http://https://somender-singh.com/images/Slider/Racer-Trophies.jpg |
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Title: Re: Compression Project Post by Dave on 09/03/19 at 10:42:13 The Singh grooves cut into the flathead/sidevalve head do look like they would help the flame front travel to the far corners of the combustion chamber....the far edge if the piston is very far away from the spark plug. The machining marks are a good indication they have cut the head down to reduce the combustion chamber size to increase compression in this engine. I am not so convinced it would help the Savage much - the spark plug is central to the combustion chamber, and the size of the squish areas are very small....and the combustion chamber is mostly open as the piston is flat and the head is domed. I don't see how the travel of the flame front is restricted in any way. But......I am also not an expert in this area! :-? |
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Title: Re: Compression Project Post by DragBikeMike on 09/03/19 at 12:40:32 Jeeez Lancer, that case damage incident sounds like it could have been a lot worse. You're fortunate that road hazard didn't bring you down. Ouch!!! What did that Veypor computer gizmo give you for HP & torque? Batman, those grooves sure look interesting. I'm lovin that old-school sidevalve head. Ah, the good old days. The pentroof sure is pretty. Thanks for the pictures. I will give the grooves some thought. I intend to be tearing it down fairly soon to add the next stage of modification (the larger valves), so who knows, maybe I'll try the grooves. But to be honest, I don't see the technical merit. One of the objects of the tight quench is to force the hideout charge out of the quench area, the groove sort of defeats that. I agree with Dave, the concept seems more credible on the sidevalve. One big downside of that groove is it is absolutely not reversible. If it doesn't work out, the head is a boat anchor. But I will google search this guy Singh and see what he has to say. You got any pics of the groove you put in your carburetor? You have some bonafide first hand experience with that so I would say it warrants a closer look. |
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Title: Re: Compression Project Post by LANCER on 09/03/19 at 14:46:50 Seems like the hp worked out to be about 42. I had some difficulty when I initially tried to use the program and came up with an odd assortment of numbers, but got the procedure down and got consistent numbers. That is where 42 came from. I do not remember the torque number. Do the time, speed and hp numbers seem appropriate ? 12.1 sec, 89mph in the 1/4 mi. from 42 hp and with a total weight of 550 lbs. bike & rider ? ? |
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Title: Re: Compression Project Post by Armen on 09/03/19 at 17:57:04 Hey Batman, Had to dig thru the factory manual for the cam timing numbers. Here they be: |
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Title: Re: Compression Project Post by DragBikeMike on 09/04/19 at 02:36:07 In response to Lancer’s questions “Do the time, speed and hp numbers seem appropriate? 12.1 sec, 89mph in the 1/4 mi. from 42 hp and with a total weight of 550 lbs. bike & rider??” Not having swung a leg over the motorcycle in question, I can only comment based on my own limited experience modifying engines and play racing over the years, various books that I have, and readily available calculators that can be found on the internet. I am by no measure an expert on the Savage, that’s why I hang out in this forum. Lancer provided the following information on engine modifications. Bore 94.5mm, CR stock, Stage I cam, good flowing muffler, stock carb with a dial-a-jet. Looks to me like a very mildly modified engine with stock compression, free flowing exhaust and a mild street cam (about 220° duration). Increasing the stock horsepower from 30 to 42 represents a 40% improvement. That seems optimistic given that the cylinder head and compression ratio are stock. Generally, modifications like this would probably result in a 10 to 15% improvement in HP. For example, when I did the dyno run on my engine after installing the DR650 cam, modifying the muffler & airbox, machining the flywheel, and rejetting the stock carburetor, I had an 11% improvement. I thought that was reasonable for the level of modification. So, IMO the 42 HP predicted by the Vaypor computer is suspect. That could be a result of any one of several variables (vibration, input error, issues with the download, corrupted data, erroneous data, bad satellite link, etc.). The quarter mile speed seems out of line with the elapsed time. I have a table from “The V-Twin Tuner’s Handbook” that correlates MPH & ET. A 12.1 ET correlates to 108 mph. If I go the other way, 89 mph correlates to a 14.51 ET. I personally think that for the Savage, a 14 second quarter is respectable. If you consider that road tests in motorcycling periodicals pegged it as a low 16-second/high 15-second econo-cruiser, runs in the mid 14’s are a big improvement. If you use any of the readily available calculators on the internet, significantly more than 42 horsepower would be required to hurl the Savage through the traps in 12.1 seconds. Those calculators align closely with a formula in the V-Twin Tuner’s Handbook. That formula is: ET equals 6.183 times the cube root of weight over horsepower. If you crank Lancer’s weight and HP value through that formula, you get an elapsed time of 14.5 seconds. To arrive at a 12.1 second elapsed time, the formula predicts that you must increase HP to 73, or reduce weight to 320 lbs. If you want to play with some of the calculators, here’s some links. None of these calculators or formulas are perfect, but they are useful tools. Estimate quarter mile ET from MPH https://speedmaster79.com/tools/14et-mph Calculate ET and trap speed from HP & weight https://robrobinette.com/et.htm ET & MPH calculator http://www.wallaceracing.com/et-hp-mph.php Formula for ET from HP & Weight https://www.stealth316.com/2-calc-hp-et-mph.htm |
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Title: Re: Compression Project Post by batman on 09/04/19 at 05:53:05 Dave , a closer look at the 4 valve GSX head pictured above shows hot only the V shaped groove at the exhaust valves ,but the small grove leading from that down the ridge between the valves to the sparkplug. The large grooves provide the swirl as the piston rises, and the small grooves provide an accelerated path for the flame front , back to the quench zone to insure combustion in that far area , as the piston drops . Mike's quench area is .060 not ideal . While adding the grooves may reduce Mike CR slightly ,this may not be all bad, when you raise CR by one point from 8.5 to 9.5 you gain about 5% more power ,but raising it from 9.5 to 10.5 you gain only about 2.5% . Mike 's present CR is 10.41 ? He may still have 10:1 even with the grooves , and reduce his 245 static CR to somewhat closer to 200 psi, something the stock piston(casting) can handle . The motor should run cooler , and is another thing that should be considered , higher CR ,comes with higher ignition/head temperatures. |
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Title: Re: Compression Project Post by Dave on 09/04/19 at 06:35:15 Batman: If this is the picture you are referring to.....I only see some pencil marks where they intend to file some grooves, and the start of one groove. I looked at the site that was linked, and even looked at the video and I did not see the completed head. I can see how the little grooves might help to get the flame front moved to the squish area.......my mind doesn't really have the ability to comprehend a combustion process that happens 30-40 times each second! http://www.mtfca.com/discus/messages/331880/363115.jpg |
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Title: Re: Compression Project Post by batman on 09/04/19 at 06:46:58 Dave , why not go to Singh's website and look at a finished head ? |
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Title: Re: Compression Project Post by Dave on 09/04/19 at 07:04:14 3A392C3539366C60580 wrote:
I followed the link: https://somender-singh.com/index.html I looked at the videos, I opened the gallery....I looked at his thoughts, and I never did find a photo of the finished head. |
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Title: Re: Compression Project Post by batman on 09/04/19 at 07:20:47 Just type, sommender singh , and hit search. you'll find plenty of pics if you llok down the page to the gallery . You might also look up test results of the Singh grooves by Garrett Robert Hering.- http;//www.heringg.com/singh Keep in mind that this test was performed on a two valve head, GEO motor, with one groove and one small quench area. I have faith that results would have been better if a 4 valve head motor would have been used. |
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Title: Re: Compression Project Post by verslagen1 on 09/04/19 at 10:55:37 Egad... found it. http://www.herningg.com/projects/groovyheads.html |
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Title: Re: Compression Project Post by Fast 650 on 09/04/19 at 12:14:57 I have looked at several sites where people have tried this modification. They all make the same mistake in their testing... they test the engine in stock form first, then mill the heads and groove them and test again. I haven't found a single test where they compared just a milled head to a milled head with the grooves. So how do you tell if it was the grooves that made the improvement or if just milling the head alone was what made the improvement? |
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Title: Re: Compression Project Post by LANCER on 09/04/19 at 15:15:59 Thanks for your evaluation. |
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Title: Re: Compression Project Post by justin_o_guy2 on 09/04/19 at 15:45:44 Looks like teething pains are included |
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Title: Re: Compression Project Post by batman on 09/04/19 at 19:41:18 Vercy just showed you the site. A GEO motor two heads ,both rebuilt to stock specs, one with Singh grooves , one stock - both mounted to the same stock motor. with the stock gas tank, fuel pump, exhaust , and tranny. |
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Title: Re: Compression Project Post by verslagen1 on 09/04/19 at 19:53:12 Batman, you spell like joker. ;D |
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Title: Re: Compression Project Post by Fast 650 on 09/05/19 at 10:16:42 3C3F2A333F306A665E0 wrote:
Sorry, the only thing that my browser shows in that link is two different smallblock Chevys. |
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Title: Re: Compression Project Post by DragBikeMike on 09/05/19 at 14:24:12 I reviewed Mr. Herring's report. He did a powerfully impressive test. A lot of work obviously went into that. I am trying to make a hotrod. WOT performance is most important to me. I am willing to put up with poor fuel economy and minor drivability issues in exchange for the best WOT performance I can achieve. Nowhere in the test does Mr. Herring take it WOT. Best I can tell it never gets past 30%. Looks to me like his high load data is achieved by throttling the load cell bleed, not the fuel injection system throttle body. He even states in his summary that torque, power and thermal efficiency were "unchanged at high loads". I think Mr. Singh's invention has merit for improved fuel efficiency and drivability. I was confused at first because on almost every data table the stock cylinder head made more horsepower than the grooved head. Then I figured out that the hydraulic load cell oil temps were higher for the grooved head tests, and as such, registered lower pressures which in turn resulted in lower HP readings. You can find that nugget of gold in his notes. I was baffled that he didn't make an effort to use some sort of correction factor to adjust for the hydraulic oil temp. In his introduction, he states that his test is intended to confirm or disprove the claims listed in US patent 6237579. I pulled up that patent. It's really cool. First time I ever tried that. Best as I can tell, I think what's goin on here is an idea that is intended to improve fuel efficiency & drivability while at the same time lowering emissions. All good things. I don't think it's intended to make my Savage a hotrod. The patent description does say the invention should allow higher compression ratio and decrease the tendency to detonate, so I will keep it in mind if the detonation issue turns out to be a real problem. But I think I would lean toward dishing the inexpensive piston rather than grooving the expensive head, especially since my issue seems to be confined to WOT high rpm operation and this groove thing only seems to affect low & mid range ops. The US patent office didn't hand Mr. Singh that official number for the heck of it. There is obviously some merit in the invention. |
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Title: Re: Compression Project Post by Dave on 09/06/19 at 05:11:47 797F700C0E090D3D0 wrote:
I don't believe the US Patent Office does any testing to prove something works to issue a patent - you just need to have an concept that is novel and unique and different from other patents that have been issued. I believe a lot of patents have been issued for things that may not work in the real world. I go to a Banjo Collectors gathering where they have folks giving presentations - and one year a fellow showed Patents that had been issued for banjo related gimmicks......most of them were never actually put into production as they had no real merit in the real world and did nothing to improve the banjo. |
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Title: Re: Compression Project Post by ohiomoto on 09/06/19 at 06:06:14 I've been mildly interested in Singh's work for several years, but I'm not enough of a gearhead to bother. I was hoping DragBikeMike would take the bait! :) If I had a reason to pull the head off of my bike, then I would probably do it, but it would just be a "seat of the pants test". Unless my MPG improved significantly because I do keep tabs on that. If I remember correctly, he used this mod on some race bikes??? I think that was somewhere on his site. |
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Title: Re: Compression Project Post by DragBikeMike on 09/06/19 at 12:29:58 The patent office doesn't evaluate the merit of the invention??? Ooooops! My bad. :-X I didn't know that. You learn something new every day. |
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Title: Re: Compression Project Post by Fast 650 on 09/06/19 at 13:11:43 All you have to do to get a patent is pay the $200 filing fee and write up a vague description of what your patent is. Many are intentionally vague in hopes that someone will accidentally infringe so that you can sue them for infringement. A few years back someone worded it so that the meaning was not obvious, but they filed a patent for hyperlinks, which have been in use at least since the days of Windows 3.1. Had someone not realized what that patent really was and pointed out prior work, every single web page worldwide would have been infringing and would have had to pay royalties for infringing on that patent. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:46:06 When I left this saga back in August, I had a flat tire and suspected detonation. The project had to go on hold until I could get a new tire. My plan was to add more fuel, install a colder plug, try pulling out some ignition advance, and install a wide-band air fuel ratio (AFR) meter. Now its time to report how all that worked out. The DPR9EA spark plug worked fine. No fouling problems. The #66 main jet was a dog. It killed acceleration. So the 62 main jet went back in. I still suspected that I might be hearing some spark knock, so I pulled off the alternator cover and modified the ignition pickup. It’s not difficult, but it is humbug. As previously mentioned, about the most you will get out of elongating the mount holes is 2°. My calculations indicate that for every .051” you shift the pickup along the circumference of the rotor, you change the timing 1°. That’s an important number because each time you adjust it you must tear off the alternator cover, so it’s good to have an idea how far to move it. Guesswork here would suck. Once I had the cover off, I fabricated a simple tool to establish the exact radial position of the pickup so I would be able to relocate it and verify that the air gap would not be altered. It’s located 2.913” from the center of the stator. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:47:02 Then I established a reference so that I could return the ignition timing to the stock position in the event that the retarded timing didn’t work out. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:50:20 Now it was time to modify the mount holes to allow the pickup to be moved. Its highly magnetic, so as you are filing away at the holes, the filings want to get into every nook & cranny. Also, the wires are permanently attached, so you have this bundle of alternator stator and mag pickup to juggle. I made a little wood block setup to hold the pickup while I worked on it. I used masking tape to keep the filings out of the nooks & crannies. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:51:04 This gives you an idea of what to expect when you start filing. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:51:48 Depending on whether you want to advance or retard the timing, one hole gets elongated closer to the pickup body, and the other just gets opened up completely. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:52:28 I shifted the pickup .102” in the retard direction, and reinstalled it using the special tool to verify air gap. Loctite seemed in order. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:53:57 I put it back together and verified that the ignition timing was retarded about 2° by shooting it with my strobe light and special timing fixture. It was now 0° BTDC at idle and 27° BTDC above 4000 RPM. That looked good to me. The spec for full advance is 30° BTDC. I wanted less advance for two reasons. First, the tight quench and increased compression require less advance because the mixture turbulence is improved. That mandates less ignition lead and I had felt from the beginning that the engine would run better with less advance. Second, I suspected it might be detonating and pulling advance out would improve that condition. At this point, I had also installed an AEM wide band AFR system and was ready to get some good data. After running the guts out of it in 1st thru 3rd gear, I could see that I did not have anything close to a lean condition. It was running very good but I was still getting little noises and rattles. I just couldn’t rule out detonation. I figured I should kill it with kindness. It had plenty of fuel, and I pulled out some advance, and the plug was certainly cold enough. Let’s amp up the octane and see if the mysterious noise goes away. I picked up a product called “Race Gas”. It’s an additive that supposedly can increase the octane of pump gas from like 92 to 106. I did a little research on the internet but mostly got stuff that looked like infomercials on the HotRod channel. I talked with the guys at the local speed shop and they said the stuff is legit. I also talked with some of our local import street racer crowd who are major big into boost, and some of them said it does the trick. So, I bought a very expensive can of the stuff. Any of you ever heard of it? |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:56:14 After playing around with octane, I still didn’t feel sure that there wasn’t any detonation. Sometimes there was absolutely no unusual noise, other times I could swear I heard rattling. I did find some rattles associated with the lanyard for my GoPro. I eliminated those. So I figured it was time to really ring its guts out. I tried a few land speed record (LSR) runs. By now, many of you have probably seen my post on the crankcase breather. When I started trying to break the sound barrier, I noted that the AFR would flatline rich once the engine hit 7000 RPM in 4th gear. That tuned out to be the crankcase breather puking oil into my airbox. That resulted in two things. The AFR going grossly rich, and what I am now sure was detonation. Oil contamination of the fresh charge will cause detonation, and I was now getting indications of detonation on my spark plug reads. Tiny little silver balls were showing up on the electrodes. I fixed the breather issue with a special catch can & vent assembly. The engine now pulled clean past 7000 RPM. My acceleration time was still right at 2.9 seconds in 2nd gear from 4K to 7K. I knew it was running well, but I wanted some concrete data. Time for a dyno pull. To prep for the dyno pull, I thought it would be wise to get a look at the cam chain & tensioner. I had logged 310 miles since the post break-in inspection. That’s not a lot but it sure would be embarrassing to oil down the dyno. I pulled off the clutch cover and took a look. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:57:24 The tensioner was still extended exactly 18mm, right where I left it at the last inspection. The 310 miles I had logged since then were brutal. All sorts of 2nd gear 7500 rpm pulls, dozens of trips through the first three gears at WOT. Five LSR runs all the way to 7K or more at WOT. That thing was WOT at every opportunity. I know the general consensus is that the short runs are toughest on the cam chain, but this uber high rpm stuff isn’t exactly pampering the thing. I was very pleased to see the tensioner still at 18mm. Very encouraging. The drive and slack sides of the chain still have ample margin. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 04:58:38 The dyno told me what I already knew. This 40-incher is runnin good. It made 40.94 horsepower at 6600 RPM, and 38.35 ft-lbs of torque at 5050 RPM. It makes in excess of 30 HP (stock output) from about 4300 RPM all the way to 7400 RPM. It makes in excess of 30 ft-lbs from 2800 RPM all the way to 6800 RPM. It’s a sweet powerband that just doesn’t quit. |
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Title: Re: Compression Project Post by DragBikeMike on 10/10/19 at 05:01:23 The S&S carburetor is dialed in as good as I’m gonna get it. A bit rough around the edges, but certainly easy enough to live with. The stock airbox (modified) and K&N filter are keepin up just fine. The stock muffler (modified) and MAC 1.79” ID header are handling the exhaust chores admirably, and it’s still very quiet. I have done a couple of additional mods to the muffler and I will update that post later. The DR650 cam has proven to be the bargain of the century. When you consider how big the carb and header are, and then look at the flat power curve, you must give at least half of the credit to the cam. Of course, the bumped-up compression and tight quench deserve the other half. The redline shows the souped-up Stage II head certainly flows plenty good. I guess I will never feel comfortable with the high cranking pressure. With this much compression, I will always feel the need to feed the beast enhanced fuel. I plan to finish up the rest of the additive and then start planning to tear it down. I want to try and dish the piston and find a cam that closes the intake closer to 50° ABDC. I need to get the dynamic compression ration down to 9.2:1 (about 190 psi). That way I could be completely comfortable with 92 octane E10. For now, I think I will enjoy the little Savage just the way it is. Have some fun with it. Rip it up a bit. Get a better feel for how well the cam drive holds up. This project has been a lot of fun so far. Hey, it’s a HotRod disguised as a mild-mannered reporter. |
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Title: Re: Compression Project Post by Gary_in_NJ on 10/10/19 at 05:29:56 Mike, Impressive work, and impressive results. |
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Title: Re: Compression Project Post by Armen on 10/15/19 at 12:31:52 Thanks so much for sharing the results of your hard work! So, care to make any guesses as to HP increase by fixing the crank breather puking? Maybe I should ask that on the other page. |
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Title: Re: Compression Project Post by DragBikeMike on 10/15/19 at 14:16:24 Actually Armen, the dyno run was done after I installed the catch can. So it makes just about 41 HP with the catch can mod. It would be nice if I could install a check in the breather line and then dyno again, but I would have to be independently wealthy to work like that, plus I need a lot more free time. Maybe I should buy a dyno and install it in my garage. I don't think my current test regimen, 2nd gear pull on video, is sensitive enough to measure improvements as small as a check valve in the breather. Who knows, maybe a check in the breather would result in a measurable decrease in acceleration time from 4K to 7K. You can be certain that I will try it. But I can't imagine it would be that dramatic. |
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Title: Re: Compression Project Post by jcstokes on 10/15/19 at 14:58:15 What a lovely photo, aside from the carburettor and handle bars, it's hard to tell it's not stock, you should feel very proud. |
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Title: Re: Compression Project Post by DragBikeMike on 10/27/19 at 23:28:36 Since I have it all torn apart to fix my sucked out cylinder base gasket, I looked over all the particulars to see how it's holding up. I've put right about 1000 miles on it since I did the mods to increase compression and tighten quench. About 500 of those miles have been real torture on this engine. It has seen a ton of WOT operation. The cam chain tensioner plunger is still right at 18mm. The front & rear chain guides look fine. |
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Title: Re: Compression Project Post by DragBikeMike on 10/27/19 at 23:30:39 The combustion chamber looks fine. No signs of detonation. Only a very thin coat of carbon, maybe .005". Valves look great. Nothing ugly goin on here. |
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Title: Re: Compression Project Post by DragBikeMike on 10/27/19 at 23:34:09 The piston crown looks good too. Also no signs of detonation. Same light coat of carbon just like the combustion chamber. Valve reliefs show no sign of deformation. Looks like the crown can take it. The underside of the piston looks good too. Nice and silver, no indication of coking or discoloration, so it's not getting too hot. |
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Title: Re: Compression Project Post by DragBikeMike on 10/27/19 at 23:35:16 The piston skirt has no signs of galling or seizure. |
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Title: Re: Compression Project Post by DragBikeMike on 10/27/19 at 23:38:22 The special tensioner plunger is lookin good too. No unusual wear. It does have a bit of a polish on the edge, but overall looks just fine. |
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Title: Re: Compression Project Post by DragBikeMike on 10/27/19 at 23:41:26 So far so good. It runs good and is holding up well (except for my breather/gasket fiasco, that really isn't associated with this compression project). I think this is going to be a solid mod. |
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