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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Squish band /cgi-bin/YaBB.pl?num=1518089629 Message started by batman on 02/08/18 at 03:33:49 |
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Title: Squish band Post by batman on 02/08/18 at 03:33:49 I know the standard way of tightening the squish band is shave the top of the cylinder. I've always wondered if it couldn't be reduced by removing the gasket under the base of the cylinder and sealing it with a thin coat of something like yamabond,or if heat sensitive ,something as simple as a gasket cut from aluminum foil, or am I being crazy? I welcome comments. |
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Title: Re: Squish band Post by Armen on 02/08/18 at 06:31:26 On early Airhead BMWs, there is an aluminum base gasket. By the mid-70's, the gasket was eliminated, and 2 o-rings were used on the top stud holes. When I work on the early ones, I eliminate the base gasket and counterbore the underside of the cylinders for the late style o-rings. This does two things-it eliminates 2 gasket surfaces, raises the compression a tiny bit, and tightens the squish band a bit. Always a happier bike. When Norton went to 850ccs, they had trouble with the cylinders murdering the base gaskets. They worked with Loctite to develop a gasket goop that could be used in place of the base gaskets. That product still exists. So, IIRC, there aren't any o-rings on the cylinder base. Lose the gasket and goop it up. I believe Lancer skimmed the head and the cylinder. And used a high compression piston. Kinda tells me the bikes can tolerate a lot more compression and a much tighter squish band. Start with measuring the squish band with the stock used head and base gaskets. Then measure the used base gasket. In there somewhere it would be good to actually measure the combustion chamber and calculate the compression. My guess is that the bike could tolerate about .040"/1mm of squish. If this results in a really high compression ratio, start to lose the sharp edges on the valve pockets in the piston crown. My 2 cents. |
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Title: Re: Squish band Post by Dave on 02/08/18 at 17:24:23 I was able to find a remnant of a base gasket.....it squished down to 0.018", while a used head gasket is 0.025". The flat piston top on the stock piston is 0.160" down from the top of the cylinder! (NOTE.....later measurement was 0.172" with base gasket intact). I measured the distance from the piston crown to the top of the wrist pin bore on a stock piston and it is 0.645". The Wiseco is not a flat top piston, and it has a flat ring around the edge that is 0.670" from the top of the wrist pin bore - then when the dome starts it is 0.732 above the wrist pin (there are some valve reliefs cut in the piston). All of my measurements are done with a dial caliper of Asian decent, and the accuracy is not guaranteed! |
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Title: Re: Squish band Post by Armen on 02/08/18 at 17:41:22 Dave, Was that .160" without head and base gaskets? That's more like shoe-to-foot clearance :o |
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Title: Re: Squish band Post by batman on 02/08/18 at 20:37:12 Armen ,check out Somender Singh - Groves (U.S. patent 6237579) |
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Title: Re: Squish band Post by batman on 02/08/18 at 20:43:59 Dave, thanks for taking the time to do the measurements ! |
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Title: Re: Squish band Post by Armen on 02/09/18 at 02:58:48 Batman, Are you going to try those grooves on your head? |
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Title: Re: Squish band Post by piedmontbuckeye on 02/09/18 at 04:29:21 6C575A4D5C504B4D565E534C3F0 wrote:
I hope so!!! ;D |
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Title: Re: Squish band Post by Dave on 02/09/18 at 05:40:58 Well.....the piston stop about 3 dimes and a dog hair below the top of the cylinder. http://i63.tinypic.com/11kz69y.jpg I measured in the area without carbon on the piston this morning, and it is 0.172" http://i68.tinypic.com/24wajo6.jpg |
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Title: Re: Squish band Post by batman on 02/09/18 at 22:42:22 Armen , I might ,this guy is no joke! I first read about him in 2004 in Mechanic's Illustrated ,at that time he was just doing it to Briggs and Stratton mower engines (flat heads), but even then they produced more hp with less fuel, and ran cooler exhaust temps.(I think that could only happen with more complete combustion ) Even if the groves didn't work ,would they do any harm? I think they would only aide in what your doing by reducing the squish zone. |
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Title: Re: Squish band Post by Dave on 02/10/18 at 04:36:22 I watched several YouTube videos of folks with hacksaw blades and files.....but I didn't see anyone with actual test or dyno results. Mr. Singh seems to believe in it and is trying hard to promote it. If it really does provide a 20% improvement....it is hard to believe somebody hasn't paid the patent fees and put it into use on a production car or truck. https://pesn.com/archive/2005/10/13/9600187_Design_to_Improve_Turbulence_in_Combustion_Chambers/index.html |
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Title: Re: Squish band Post by Armen on 02/10/18 at 05:46:39 Two things: How long before the groves are full of carbon? Are those sharp edges going to get hot in a high compression combustion chamber and provide a starting point for pre-ignition? |
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Title: Re: Squish band Post by Dave on 02/10/18 at 07:49:05 The squish on the Wiseco is better than stock - but it still may not be ideal. The piston is really made for the DR650 - but it does work in the Savage and is better than stock.....perhaps it could be better. |
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Title: Re: Squish band Post by batman on 02/10/18 at 09:23:37 Armen, check out ,Herningg.com/singh/engine , a complete test of a Geo three cylinder engine with stock head and a Singh conversion head. A stock Savage motor with 8.5:1 compression will form about 850 lbs of pressure as the piston rises , try to think about how much velocity this will create in the slot, I don't believe carbon will have a chance of forming and causing hot spots. In singh's patent the slots were v shaped, which may have caused them to lose velocity and cause hot spots ,in the motor test above they were revised( by Singh) to straight slots 3/32 wide ,starting .040 deep at the outside and increasing depth at a 4.5 degree angle as they run toward the combustion chamber. I believe this will prevent any drop in velocity and thus keep any carbon from forming. |
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Title: Re: Squish band Post by Armen on 02/10/18 at 15:19:28 So, it sounds like measuring the actual compression ratio and the squish band is a good idea ;) And don't forget to advance the cam timing after shaving the cylinder. Hey Batman, why not yank the head on your bike and try it? One way to find out. Dave, If this bike really has .160"/4mm of piston to head clearance, that may be a lot of the reason the motor is so gutless. |
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Title: Re: Squish band Post by batman on 02/10/18 at 15:58:11 Armen I may do just that but right now my garage is unheated and 15 degree daytime highs don't play well with grabbing wrenches. |
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Title: Re: Squish band Post by Armen on 02/10/18 at 16:03:49 Yoiks! That's what my garage is like now, which explains why I'm typing inside where it's warm ::) |
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Title: Re: Squish band Post by batman on 02/10/18 at 16:10:15 Dave ,Singh not having a formal education ,tried to get is engines tested in India but the Four places refused to except to do it, stating that they could not test a modified motor unless he received permission from the motors manufacturer ,which was denied ,even though he offered to pay for the testing himself. Two racers in the USA modified some motors and were so impressed they helped him through the long process ,to gain his US patent. He presented his mod to the big three and other companies and was largely ignored.( pressure by Big Oil?) |
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Title: Re: Squish band Post by LANCER on 02/10/18 at 20:09:12 The combustion chambers of a 1990-95 DR650 and an LS650 are virtually identical; same size, shape, and with the same valves. The only real difference is the exhaust port and camshaft and a very slightly shorter stroke. |
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Title: Re: Squish band Post by Dave on 02/11/18 at 03:41:15 49444B4640571712250 wrote:
How far from the top of the cylinder is the piston at TDC on the DR650? |
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