you don't want to lean the motor or blip the throttle during break in. If it stays running rich that's where you want it. To get the temps up wrap the cooling head in aluminum foil and cover that with a baby sock. This was it has tons of lube from being rich yet it's in the temp range you want for break (over 200F)

When you say "the engine cuts out" does that mean it completely dies or it lean bogs and stays running?