Abgeschickt von Sven am 18 April, 2007 um 08:44:55:
Antwort auf: Compression ratio von Matz Rosenquist am 17 April, 2007 um 22:40:51:
Hi, there
David and Martin are absolutely right ! I have 2 bikes tuned with the original S-pistons, an 800 cc G/S of 1982 with a compression of 9,2 and a 1000 cc Mystic of 1994 with a compression of 9,5. In addition both have the regular 320 Schleicher cam ( RO 240.6 ), the 4V ignition coil, a bit more open airfilter systems, the Mystic also has 44 mm inlet valves and the G/S got 40 mm outlet valves. All that are more or less cheap, simple and easy to do changes, but the effects are quite amazing. So, I can only recommand that kind of "low end tuning".
Good luck,
Sven
: G'evening All!
: I've got this old rundown G/S, the HP(n), and I'm currently trying to find out how to raise the compression ratio. The idea is to raise it to 9,5:1 by either grinding off the head or the cylinder foot by 1,5 mm.
: I've checked the clearance between valves and piston and the intake valve (closest to piston) clears by approx 2,5 mm with everything standard. So this should not present any problems.
: Now, what about the squishband? The piston and the edge of the squishband clears eachother with a little more than one mm (hard to tell as the modelclay I used was difficult to check) standard. This have to taken care of somehow.
: What do you propose as a suitable way to raise the compression ratio? Grinding off the head? Cutting off the cylinder foot? What about the squishband? Any other ideas? And no, I don't want to keep it standard!
: I'm using an HPN 320 camshaft with everything else kept standard, just some minor clearing up in the intake ports plus an open airfilter, HPN version. Exhaust is some old gimbojimbo which will eventually be replaced by my own design.
: I know there's a lot of knowledge collected out there in HPN-land, and I would appreciate any advise given in either German or English.
: Thanks in advance!