Are you sure you have timed it per the rear cylinder on the compression stroke and the points in the mag with the foot or rubbing block of the points at the lower ramp on the cam ring at @ the 6 to 7 o'clock position, remember the points rotate anti clockwise at the points end. If your not sure about setting up the rear cylinder, remove the two tappet inspection caps to see what the valves are doing when you turn the engine over. Remove the spark plugs to make turning the engine easier. Good luck............Greg.