Re: Bought bottom end from Boy Go Fast, should I be worried?
You need to measure the distance from piston to head once the engine is assembled.
I have one engine running a 40mm crank and anglefire head, but I have taken quite a bit out of the chamber to lower compression and have a squish of around 2mm.
I use solder to measure the squish.
stick it in the plug hole and turn the motor over, makesure you get the solder right to the edge of the chamber.
My experience with to high compression and angle fire head had my motor running a little warm and pinging above 8000 RPM.