My son has a 89 Yamaha 100 moto 4 that burns a lot of oil and smokes. It still has a lot of power and speed. It goes over 35 MPH with me (over 200 lbs) on it!
Anyway this winter I plan to fix it for him. My question is this:
Is it probably just the rings, or should I plan on getting more? Also I know of a couple places on line to get parts, but they don't seem to be great deals, anyone know of any good places to order these types of parts? I don't want to go too high tech and performance, he is only 10 and this one scares him a little as it is. I just want it so he doesn't have to put in a quart of oil every time he rides.

 

You won't be able to tell what all is wore until you open it up. Chances are it is just the rings. I really think your local yamaha shop would be pretty competitive on parts like this. If not, try denniskirk.com, or maybe ebay.

 

A compression test should let you know if it is the rings or not. Anothe rplace to look would be the valve seals (the moto 4 is a 4 stroke, right?)