1. put a
little fuel down the plug hole to make sure the piston is wet.
2. Keep the plug in. Loose plug will only bleed off compression, not mechanical pinch. The pinch is your problem any decent box can defeat the tiny bit of compression these little two strokes have.
3. Heat that engine with a heat gun. 180-200. Use a harbor freight cheapo heat gun. hobby heatguns are fragile and lame. Especially hobbico and tower.
Houston has some nice heaters. But i've never used one for break in.
4. Put a 4cell 4500mah Turnigy Lipo in that starter box. Don't use a weak gell cell.
5. make sure the pistonis at BDC, and nice and free before you bump it. That way it has a head start and some momentum before hitting that pinch.
6.
Get an OS. LOLz.