My friends Warrior breaks up from 1/4 throttle to 3/4 throttle. He doesn't have a book so I was wondering if you guys could help with the problem. Do you think its the jetting? It only has an airfilter on it. I never really tuned a 4 stroke before so I didn't want to touch.

 

On a Warrior....if this just started "out of the blue"..there are a few things to check which happen often with this model.

First,..check to make sure he doesn't have the parking brake activated or a faulty brake switch. [You will find this on the clutch lever]

Secondly,...check and make sure the ground wire on the reverse selector handle isn't loose or corroded.

Third,..check the intake boot between the carburetor and engine for cracks first.

Check the vent hose coming from the SIDE of the carburetor and make sure it not stopped up with dirt.

Check the air intake tube into the airbox[from frame]. Dirtdobbers are bad about building up here causing a major air restriction to the carburetor.

If these check out, you will likely have contaminated gasoline or carburetor...or both. Flush the tank and fill with fresh gas from a CLEAN container. Take apart and clean the carburetor.