I read on a newsgroup to use an old crockpot and some antifreeze. Disasemble the entire engine and put contents (minus o-rings) into the pot and heat for 8~9 hours. When done rince with hot water and dry everything with a soft cloth. Then lubricate with oil (didnt say what type, WD-40 or after run should do) Also be ware of YS engines with pumps, dont clean them with the above method.
I havent tried this myself yet but I just recently found a crockpot to use and will soon try it out. Of course DO NOT use the pot again for cooking food!!!!
I used to use a popular engine cleaning chemical (z best) but that stuff would dry up just sitting around and is quite expensive. The crock pot should be cheaper and safer to use....hopefully it works good. I'm going to use it outside to avoid any fuses escaping into the house.
Let ya know how it works for me. Later.