Clean out the whole engine with the fuel you use. Take the whole thing apart. Check the sleeve and piston for damage(deep scratches), check that the front and rear bearing are clean of shrapnel and put your engine back together, seal it air tight so you dont get no air leaks or you'll ever heat it. When that's all done look in your manual to find the factory carb settings for you high speedand low speed needles so you no where you are, fire up the engine and keep it alive using the transmiter throttle. Dont give it to much gas(1/4-1/2 is plenty). Now set your idle screw so the engine keeps ticking over on it own. Let the engine warm up to running temp. Now tune the HIGH speed needle but watch the temperature and make sure there is ALWAYS an nice trail of smoke coming from your pipe. Hope this helps.