You time at max advance, as Dave said 2.7 inches btdc on the flywheel which is 68.5mm. (this is maximum unless you want to risk breaking the crank) Once the timing is set, You then close the advance lever and alter the advance and retard lever as and when required so the engine responds accordingly, you do not want the engine running at idle at full advance. This is a manual operation by the rider for different engine pulling conditions not automatic as per the weights which throw out and alter the points plate position.
I E when auto advance is used as the engine revs slow the ignition is retarded accordingly to the manufactures spec and as the engine increases revs then the ignition is advanced, unless you have a Scott with a distributor the rider has to alter the advance and retard according to engine speed and how the engine sounds. Kev
