We changed the points, rotor, wires and plugs. The points are set at .020" and the plugs gapped at .023". The starter got bumped while the rotor was off and now the engine won't start. The rotor is driven by a small spur gear and I suspect we are now out of time since we moved the rotor to align it with the flat drive on the shaft during reassembly. I don't have a timing light so tried to check it the hard way. I have pulled number one plug, rotated the engine to TDC and checked the timing mark. Then checked the rotor position. It was directly on one. It seems to want to start but just won't quite catch. We have advanced and retarded several teeth in each direction from that point without improvement. We have spark to the rotor and from there to each plug. Does it appear we have the timing correct now? Any suggestions would be very appreciated. And yes, there is fuel in it. The carburator does need rebuilt though. Could be part of the problem. Thanks

Fred,
Start again at the beginning. You are a ways from getting it running. First off...If I have guessed correctly, you are working on an F-Cub...Right? (there is no model F) Second...it has a mag...right? (only the mag has a geared rotor) If right, the point gap should be .013". The rotor should be pointed to #1 lead (straight up) when the timing pointer points to the pulley mark, and the piston is just ending the COMPRESSION stroke. This is true only every other revolution. At that point, the mag impulse should trip. If correction is necessary, do NOT move the mag...re-install the rotor.

A service manual would be a good investment.

George Willer

F what?Are you sure you were on No.1 TDC on the compression stroke on not the exaust?