Well, the owner did tell me to "do what I would do with it". I warned him that is a bad idea. Port the head, cam, big bore, 13:1 piston. He is doing nothing but riding the kids around so hard to justify I guess. What sucks for him is he just bought this bike and has 2 hrs on it. I can tell now having been in the engine that the previous owner knew good and well that the engine was toast when he sold it. The bore otherwise is perfectly in spec! If he would have just thrown a piston in it on schedule, it would still be a strong engine. I had .003" piston clearance and maximum value is .005".
I have been warning people about these engines. They have very little piston skirt to stabilize the piston. Once the piston starts slapping a bit, they will cock in the bore and destroy it and typically right where this one is,,,right at TDC.
I will admit that this is the first teardown for me on a 700. I LOVE this engine!!!! Yamaha got it right!!! It comes apart NICE, very well designed, and tons of room for go fast parts. What a HUGE upgrade from the 660s.
