I agree about the heat issue....I tried to use 15% when I was playing with everything trying to get this engine to run right. It ran a lot hotter with the 15% than with the 10%, so I quit using the 15%.

Since I installed the pump, the engine runs fine on the 10%. I believe the extra fuel flow helps with the heat. Just like a full size recip the leaner the mixture the hotter the engine.

AS far as the vibration, I followed the advice someone mentioned in another .91 thread and aligned the prop vertical with the piston at top dead center and that seemed to help.