Make sure you pull the valve cover before using ANY motor flush (oil passage cleaner). if the valve cover or head has significant build-up DO NOT use motor flush, it will loosen the crap and it will find it's way into you bearings. this is very bad and will destroy most moving parts in your motor. how do I know this, because I killed my 22RE this way. and only found out when I took it apart to fix t-chain guides. result Total rebuild$$$.....Karl