Magneto timing '66 xlch

full bore running all you need is full advance, but for starting you need to be able to retard the ignition and for a nice slow idle, i use a handlebar mounted advance lever like on Brit bikes from the 40's and 50's and have a nitrogen gas strut to retard it when i want to retard it, works faultlessly with easy starting,
mounting it tight enough to stay where you move it to, but lose enough to retard is how most i know run theirs, then just a twist of the magneto for start or idle,

Yes, the timing mark can show up i the timing hole when when the front cylinder on the exhaust stroke too ( the engine will be 180 degrees out of time in this instance). It is essential that you're on the compression stroke and the best way to determine this , as has been stated, is to remove the front intake pushrod cover and turn the engine until the lifter drops ( when the front intake valve closes). Then very slowly turn the engine over until the narrow lobe on the points cam begins to approach the point fibre--but before it actually arrives there. At this point continue a very gentle, slow rotation of the engine and watch for the flywheel timing mark to enter the timing hole. Once in the center of the hole and the piston on the compression stroke, you are ready for the final adjustment of the mag. You can use a buzz box or test light at this point . Rotate the mag, until the points just barely begin to open, setting off the light or buzz box. Then tighten down the mag. I used set the mag points gap at about .016" and the plugs can be set from '018" to '020". Another thing to look at is your pushrod adjustement.