I have a buyang 70cc quad. The starter will turn, but will not engage the motor. The battery is showing 12.6 volts, so it should have plenty of voltage. Do I need a new solenoid or starter, or is there someway that I can troubleshoot this problem. thanks.

 

If the starter spins freely, but it doesn't turn the engine, then your starter clutch is probably slipping. Thus one way clutch allows the starter motor to grab and spin the engine, but when the engine starts up it overruns, disconnecting the engine from the starter. Without the overrunning clutch the starter would get spun up by the engine and self destruct.