I would start with the basics.If you put it in nuetral(shifter up,in between F&R),will it start and rev up?If not,replace the,gas.with fresh gas,new sparkplug and clean the carb,then retry.Are the clutches operating properly?The engine clutch(primary or drive)should be open,the belt should be resting on the shaft of the clutch.The axle-clutch(secondary or driven)should be closed(no gap,the belt should be all the way at the top.What condition is the belt?If its badly worn,or stretched it wont work properly.Hope this helps.
