Tony really good question. Do you know what your squish gap is currently? If you close it up too tight you run the risk of the piston contacting it. I think there are a lot more variables then squish to effect RPM. Are you racing on tracks with long straights or short? How long are you at wide open throttle with the maximum RPM reached?
Mike and Tony are correct, and to Tony’s point, a thinner gasket/tighter squish will lower your exhaust port and retard timing a bit. Yes, you will get more compression, but with a lower exhaust port, you will be moving the engine’s peak hp to a lower rpm band. So, if anything, tightening the squish in the absence of any other adjustment will give you more bottom and mid and hurt your top end. You should be targeting 15k in a Rok, so you aren’t far off. Just add a tooth on the rear.
Altering your rpm will change the squish.
I’ve had a 125 bike engine that was set up with .016″ squish, but if revved above 16k, would go to zero, due to crank flex.
Would start making a ringing sound above 16k, and when torn down both the piston & head would show light contact.
It never hurt anything, but I didn’t dare let it rev past that point.
I just used it as a shift indicator :)
I am sure this is happening on most engines to some extent.