i have an R60/2 1967, the bike starts first kick when cold, when hot, it will not start. have reset valves, plugs. bike has good start and the usual leaky carbs. was renovated 3 years ago....jim
This is a typical symptom of a bad or failing magneto coil. It gets hot and there's a break in the winding somewhere which separates. If the coil is spoogy (technical term!) or oozing or soft to the touch, that's more than likely the problem.
Also, is the magneto timed properly? It is timed separately from the ignition points. There are several after market manuals which have the wrong description for how to set the magneto timing and the ignition points timing. The magneto is set to provide the maximum spark at the "S" mark on the flywheel. Then the ignition is set to have the points open at the "S" mark. If the ignition points gap needs to be changed, it is not done by moving the magneto body...that's where the manuals have it wrong.
Kurt in S.A.
... when hot, it will not start...
If the coil is original, it is shot, regardless of whether it is soft or not. All the original coils are shot by now unless they are unused NOS that have not been cycled through heat and moisture. Your choices are:
1. Buy a hand re-wound original from Bench Mark Works. Cost is $225 in exchange for your old coil. I suspect the coils come from Huggett, who sells the same thing, and that is where your core will go back for re-winding and re-distribution. There is no cost advantage in buying a re-wound coil from Huggett when shipping is added, and the shipping takes 2-3 weeks.
2. Buy a modern plastic-cased Emerald Island coil from Bench Mark Works. It is not an actual reproduction or replica. Cost is $160.
For my two bikes I got two re-wound coils, then bought a plastic coil to carry as a spare.