You are correct. It would be very unusual for a Golden Flash to pink unless the ignition timing has been set over advanced, or if it was running very weak or hot. The problem bikes are the alloy head versions where the correct sporty pistons and cams are installed. You can (and are likely to) encounter pinking to some degree on anything with 8.25:1 pistons upwards. Some people are lucky and it doesn't happen but it is a common problem. Increasing the size of the needle jet by half a size and going up a couple of sizes on the main jet seems to, largely, resolve the problem. However, the root cause of the problem is the unavailability of decent fuel. 'Madditive' and some other additives go some way to boosting your octane level up to the ideal 101 and these additives also contain a lead substitute for the purpose of 'anti-knock'. It is generally accepted, also, that retarding the timing slightly should help but, the more you retard the timing, the more performance you lose. The spark plugs, quality of fuel, combustion chamber design, valve characteristics and timing advance/retard curve all contribute to the ability of the engine to burn cleanly. On a BSA A10, combustion chamber design, valve characteristics and timing curve aren't great. If you fit an ATD alongside the manual A/R lever you get the benefit of retarded timing at low revs but this will depend on the strength of your ATD springs. Along with the unavailability of decent fuel the sportier versions of the A10 are really up against it! So, increasing jet sizes, putting additive in your fuel, fitting an ATD all help and will cure the problem but are essentially a 'workaround'. I am told that certain electronic ignition systems will effect a cure as they have an electronically controlled advance curve but, as a magneto enthusiast, I'm not heading off in that direction!
