MRSHEE2014

Hello, i am new with this, i put a new transmission override 1-5 and i had problems. After finish the motor, i kick the banshee and start correctly. I started to throttle it in neutral, and inmediatly a shift enter alone and the atv start to go fast and i could stop it with the kill switch. When the motor is off the transmission Was in neutral again. I could not dissambly the banshee because or the time. But maybe you could told me some ideas about this problem. Thanks