Polaris scrambler won't stay in gear?

[yamahaXC13]

My buddy bought a 95 scrambler 400 4x4 for $500 at an auction, was told it didnt run it needed rebuilt so he bought a piston kit and the both of us spent a couple hours on a saturday rebuilding it. Motor runs great now but... when you start the quad in neutral it won't shift into forward gear, you can shift into forward gear while the motor is off, if you start it in forward gear it makes a loud grinding noise and then throws it into neutral quickly??? I don't know alot about cvt transmissions, anybody have any ideas what's wrong with it, thanks

[BeefySTi]

I had a similar issue with a 98 Trail Blazer 250 I just bought. The shift linkage that goes from the shifter to the transmission was rubbing the side of the engine and not allowing it to go completely into gear. I loosened the nuts on either side of the linkage (just like a tie rod) and spun the linkage bar so that the bend in the bar had clearance. Since then, no issues. Try that.