I recently bought a 300 xpress and it ran well for about a mounth but now my high gear seems to only use first gear. Anyone know what's up with it

 

It has a CVT transmission with no gears in it. It sounds like a clutch problem or severely worn belt. You may have to rebuild one of the clutches or both of them. If you're really lucky it just needs a new belt but I wouldn't count on it.

 

Yep, time for clutches and belt to be serviced/replaced.