Friday, November 11, 2011
Leif has asked what the autopsy results were from the Aermacchi failure at Barber and Daytona. Those who were paying attention will remember that on Sunday's 350gp race at Barber, I had a big lead on the 7th of 8 laps when the motor made a bad noise and lost power. I clutched it immediately and pulled off. Back in the pits, we found the engine turned over fine, it had compression, the plug looked good, the valve train worked fine and nothing was amiss in the carb. We started it up and it sounded and ran fine. And, it ran fine at Daytona for me on Fri. and Sat. But, Sun. when Don Hollingsworth was racing the bike going for the checkered flag out of NASCAR #4 with a big lead in the 350gp race, the motor made a bad noise and lost power. He was able to coast across the line and still win the race. Again, the bike turned over fine and had compression, but there was no time to look at it further before loading in the trailer for the trip back to Calif.
I left out one little detail: at Barber, when we were checking it over, we found the bolt holding the rotor of the Dyna ignition on the end of the camshaft was loose. The rotor is indexed to the cam with a tang in a slot and it didn't appear that the tang had come out of the slot, so we just Loctited the bolt and started the bike up. Well, when they looked at the bike back in Ca., the rotor was laying in the bottom of the fairing. Evidently, at Barber the rotor had come out of engagement and the ignition stopped firing, but then end up in the correct orientation (50/50% chance). At Daytona it fell all the way off. Oh well, it's better than a rod through the case, and I doubt will happen again.