JF,

Quote:
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-breake in as recommended by OS: full throttle and needlevalve adjustment every 10 sec from 4stroke mode to 2 stroke mode
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WRONG TECHNIQUE.
If OS are actually saying this, they don't know Jack Schitt...

Quote:
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-at idle and nose up... after about 3-6 sec engine dies.
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This would sound like your are too lean, but in flight there is no condition that would resemble this. If you pull up the plane slows down and falls back.
Fuel draw is not as difficult for the engine, as it is when it is held nose up. Transition is not to be checked at this attitude either.
If it was adjusted in "runway stance", it should work right.

Did you check for bubbles between the needle and the carburettor?

Sincerely,