Vintage Dirt Bike Q & A

so im new here... ive got my dads old 76 y125, and am going to restore it. so far so good, but the motor is locked up. i guess he let my moms brother ride it back in 87 and he didnt understand the concept of mixing gas. tough part is.... its not only the cylinder, but the crank thats seized up. more specifically the outer bearings. plan is to find one that HASNT experienced catastrophic engine failure, and freshen it up.... ANY ideas let me know. i understand the 76-79 motors will fit. the idea is not to necessarily have a dirtbike to ride everyday (ive got a new ktm for that) but to have a running restored vintage yellow smoker.

I have a 78 yz 125 motor and frame, the motor needs new piston. I'd sell for $150.00