Current state of the CRF's engine -
Ready to install a new crank and high compression piston. Cam and bore look great. Crank replacement is more preventative maintenance considering how the engine was/wasn't taken care of before we got it. If you wait too long you'll end up with a hole in the cases.
I'm impressed with these little engines. It spends most of it's time at the track near the rev limiter, and after a season of trackdays shows almost no wear on the internals. Probably could have gone another season without much of anything.
My son is designing a velocity stack for the carb to have 3D printed. The airbox looks like a big compromise, as it has a stiff rubber boot that jogs awkwardly around the shock spring and makes jetting changes difficult.
So far so good...