On a 2001 Yamaha Banshee, what would keep it from reving up?

Question

i ruled out the carb and jets.
the quad idles, but will bog out when reving.
no problems starting at all.

Answer 1

There's a lever on top of the left handlebar for the parking brake. If not all the way forward, it will cause this prob. Have just put a ruber band on it as a temp fix before.