The bike is too old, and wasn't a successful model for Yamaha. It featured counter-balancers to smooth its vibrations out, called "Omni-Phase Balancers" by Yamaha. Unfortunately, they tended to froth the motor oil at high revs, leading to oil starvation and crankshaft failures. No performance parts are available, and it's not a motor you want to push too hard. It's also a motor that seems to constantly go out of tune, requiring frequent carburettor adjustment and balancing.
