Not everybody has access to a ultra sonic cleaner like I do. I work in electronics manufacturing and have always had access to these wonderful inventions. The small ones work great for engines, 1 gallon size or whatever. I mix up all kinds of cleaners, whatever is handy (yes it could be dangerous, but I don't breathe or drink the stuff and so far nothing has blown up on me!) soak your engine in the cleaner tank while the ultra sonics help break up the gunk inside and out. Works better than anything you could imagine. A heated tank is even better, heat to around 140-150 deg. Just do this in a large area, well ventilated or outside.....