Compression and bore

[Guest]

I was just wondering what other things I would need and do to run 1170 12:0:1 compression pistons on my 1982 Suzuki gs1100e

[Nessism]

Gonna need some of the racer guys to chime in on this but I believe pistons like those are intended to be used with high duration camshafts which will knock down the trapped compression numbers some. So you wind up with needing an upgraded valve train, springs at minimum and cams of course. Even at that running that much compression may dictate use of racing fuel. No big deal for a racing motor I suppose, but you may want to fill us in on the intended use for this engine. Oh, and the starter clutch won't like that much compression either. Modding the starter motor circuit as it related to the ignition may be needed.

[andrews gs]

The thing I don't understand is I have been working on my buddy's 90 fzr600r and it has 12:0:1 compression from the factory and he can run 87 octane all day how is this. Plus this bike is going to be used as a street beast I just want raw power I'm ok with using 110 octane race fuel but it would be nice to be able to run 93 to.

[rapidray]

The camshafts have everything to do with being able to run high compression with pump gas. Have you noticed also that ALL of the new engines, with high compression, on pump gas, are fuel injected, and WATER cooled? I have been building these things for over 40 years, do yourself a favor & do NOT run more than 11-1 compression on the street! Unless you can afford to run race gas all the time. Detonation will destroy an air cooled GS engine very quickly. I build 1400+ cc big GS street engines so have experience with what I am telling you. If you already have a set of pistons, cut the domes down.
Ray.