squish lowering my compression?

[kazeck23]

Have a 951 carb and the squish is right at the max spec around 2.25-2.3 mm. Both cylinders are only pulling 110 psi on a fresh top end kit. Will this be enough to lower my compression that much? And is it practical to just get the head shaved instead of pulling the cylinders off to change out the base gasket?

Thanks!

 

[Dr Honda]

Yes, it can. But... if the engine is fresh... then the rings aren't beaded, and the compression may read low too.

BUT... if you bring it closer to the tight end of spec... you will pick up 10 psi. Regardless... 110 seems low to me. The 951 engine should be closer to 135 psi.

If you got the engine from a rebuild shop... they either didn't really check it, and just used a thick base gasket for safety... or they set it high to assure the engine doesn't eat itself.


As far as the last question... it will cost you A LOT more to have the head properly cut, and take time. You can just slap in a thinner base gasket, and be done in an hour. You can't just shave the head on a Rotax. They have to be properly re-cut. Group-K is one of the only people who do it right.

Don't forget... you will need a new head gasket also.