I called YS today. Someone in service had a few suggestions to try before I sent it back. He said from my description it sounded like the engine was "loading up". He suggested: 1 - clear out the fuel by closing the high needle and spinning to clear out fuel from combustion chamber. 2 - turn out high needle 2 turns not 2 1/2 as suggested in manual 3 - dont prime as suggested in starting procedure and if still does it, turn regulator adjustment screw in 1/8 of a turn and re-try above procedures.

This makes sense because after reading many YS post today I've noticed that sometimes the regulator adjustments are "out of wack" on new engines.

I will try these things when weather permits and go from there, thanks.