I've had some success with Tower .46 engines. Found that the low speed adjustment was critical. Also, they responded better to a mousse can muffler than to the stock muffler or the muffled tuned pipes I tried. I ran one kind of inverted, and tended to foul out plugs and burn them shortly after startup after sitting. My problem was that I used after run oil that tended to soak the plug since it was inverted. All that oil caused problems. If I replaced the plug with an old one during storage, the problem went away. Also found that there is air leakage around carb attachment bolt. A dab of silicone seal after installation should cure that. Good luck!