Saito 150 4 stroke
 

Need help! I purchased a Saito 150 four stroke engine last week. It came on a Great Planes Stearman. The engine will start and run from low idle to mid range. When I go to full throttle, it will kick back and quit.
I took the engine off the plane and put it on a test stand. Same thing. Tried different plugs and 2 kinds of fuel. Nothing helps. Has anyone experienced this problem?

The HSN is set far to lean, turn the HSN CCW by 15 minutes or 1/4 turn minimum.

Main needle needs to be richer. More fuel required at the top end