The problem is caused by the way the exhaust is mounted on the Commando. On the featherbed bikes there is negligible relative movement between the exhaust mounting points on the engine and the frame. The silencers are also rigidly attached to the frame. This results in a high resonant frequency of the exhaust system with a low amplitude. That is generally trouble free. On the Commando an almost identical exhaust was used (to keep costs down). This meant that the silencers could no longer be rigidly mounted to the frame as the frame now moved relative to the engine and exhaust system. A cheap solution was to mount the silencers to the frame using the same rubber anti-vibration mounts as were used at the head steady (more money saved). We now had an entirely different resonant system with the exhaust rigidly attached at the engine and the rigid constraint at the frame replaced with a spring in all 6 degrees of freedom. The resonant frequency dropped into the normal engine operating range and the amplitude increased to a level capable of loosening all but the most secure joint at the rigid attachment to the engine (i. e. the exhaust ring nut). Now the exhaust was free to rotate in the port this changed the resonant system once again and the amplitude increased further causing mayhem.
Its great to seal push to fit exhausts as well. I suspect the color is irrelevant and all rtv may really have the same temperature rating. Next time I will try grey to see if it withstands the high temperature application.
There is a ultra high temp one. Up to 370 C.
Well said.
