Four Stroker

I wore out my original early YS 70 and recently bought a new one. For reasons that I will not mention, I needed a new front bearing. I noticed a few changes from the original 70. The crankcase timing hole is now bored out to be twice as wide. There is also a new backplate assembly. This engine has noticably more power and pumps the tank up to a whopping 11 psi.