You need to have it cut down if you want the power. The fins on the flywheel are fan blades, they are sucking up energy that should be going to the prop. Also do not try to cut this down by yourself, if you ruin the flywheel a replacement will cost you about as much as the engine. I buy my parts from Wacker Engines, I sent the flywheel down to Peter and he takes the fins off on his lathe and balances it for $12. Best of luck with your endeavor.