Yes, ignition is not showing any signs of being faulty, however I've done so much experimenting with jetting and have seen no reduction or change from the high temps no matter how rich the jetting is. That's why I'm taking another direction and changing the ignition.
Some history of jetting/overheating/piston damage:
I had the bike on a dyno a while back. It had a 190 main jet in it at the time (largest available is 230). Dyno operator was concerned at operating temp and also that temp was jumping up higher. The dyno showed the main was extremely rich. Later that day I took it for a spirited back road blast and pulled up with a piston slap. Temps during that ride were the same as when it was on the dyno. Inspection showed mild detonation on the piston plus slight damage over the front of the piston causing the top ring to stick. The underside of the piston crown also showed it had been too hot.
With a new piston installed I had been working with richer needles and main jets. I had been trying the method of installing a much larger main jet to the point where it would be spluttering when trying to rev the bike out, then gradually moving to leaner jetting until it stopped sputtering, and fine tune from there. Problem was, I couldn't get it to splutter, and the high temps were still occurring at high rpm.
I then tried restricting the airbox and, starting with the richest main available, it would splutter quite a bit. I then changed down through the main jet sizes with the spluttering decreasing as I went, yet high temp problems were still there. I had got down to a 200 main and was about to go further when another problem occurred - Pressure had somehow been building in the gearbox and forced oil out the centre crankcase join and out the clutch cover gasket (see my other thread about spluttering). Investigating that is where I'm at the moment.
The current piston has no evidence of detonation (I'm no expert), but the crown and gudgeon pin have been very hot.
