Dave, hi !
Excuse, that I interfere, but at me the same problems at average revolutions (3000-7000 RPM).
My 63 is running rich.
Strong (for the helicopter) vibration in this range.
Fuel: 20/20
Plug: O.S. “F”
Prop: 12x8
Fuel Filter: Yes
Tank: Ok
High Speed Needle: 1 1/3 turns out (best result 10100 Rpm)
Low speed Needle: 0.8 turn open from full closed
Regulator : 1 turn out (factory set)
The engine is run in on the stand installation on the helicopter (if you remember we earlier spoke about it)

I cleaned DIAPHRAGM (there it was not so clean...)
I adjusted the valve on 0.04 (factory set - left 0.1, right 0.15)
I long achieved steady work on average revolutions, but could not make it...
At work on on an average mode and transition on single the engine stop also spits from carb fuel...
At work on average revolutions, then on maximal, THEN AT ONCE ON SINGLE - ALL ok.

I tried fuel - 30 % nitro, I tried fuel with fluid oil, does not help... What to do(make)?
How to remove vibration?
Still the question - as by the helicopter another - that what temperature mode needs to be observed cooling?
On the stand the motor was heated in on 2600 and on 9000RPM. up to 70 C. On 10000 and 5000 cooled down. - 52 C.


Little bit short cranshaft YS: