HI,

Seems like you've checked all the obvious things, one quick thing to check is for air leaks around the carb/inlet manifold.
If you spray brake cleaner or easy start around this area when the engines running it will start to revving if you've an airleak.
Spare air drawn in causes the engine to ...

Hi,

Have you removed the leg from the triple clamp, more precisely have you released the the two pinch bolts on the top clamp?

They exert force on the tube (try tightening the caps after you've tightened the pinch bolts, solid).

Matty