I took the rocket ship out today to see if it is still losing power and overheating when pushed hard after replacing the coolant and cleaning the radiators last week. The plan was to ride out I-10 to Chaffee Road, then head to Everybody's for breakfast.
It ran great until just before turning off. I was running a steady 85 indicated, probably 77 actual, when, just before turning off after maybe three miles of this speed, it started losing power again. Then, when I turned off I noticed the blown exhaust gasket again. I installed this new gasket not more than 400 miles ago and it was a good install, using a spreader to get the gasket fully installed without damage.
The temperature gauge was showing normal temperatures.
So, I will fix the gasket again and continue to try to understand the problem.