hi all, I own and race a gs1100 road racing sidecar in classic racing, period 5, for bikes up to 1982. The engine is stock except for a 1166 big bore kit which has 10.25:1 pistons. I was amazed when we put it on a dyno and it had 125 horse power. we then put 37mm keihin cr carbies on it and tuned it to run on methanol and the power went up to 137 horsepower. they are a terrific engine, great design, strong and reliable