The best way IMHO is to use anti-freeze. If you have an old crockpot it's best to use this, but if not you can use an old pan. Please be advised that this needs to be done in a VERY WELL VENTILATED area, outside if possible. Also note that whatever crockpot (or pan) you use for this should NEVER be used to cook food in again.

Disassemble the engine being as careful as you can to NOT move any of the parts. If there is dirt inside the engine and you turn the parts it will scratch the insides of the motor. As you take it apart remove as much dirt as you can. Place the parts in the crockpot and pour in antifreeze to cover the parts. Turn the crockpot on and let sit overnight. This will remove all carbon scouring and leave your motor looking new again. Put the motor back together.

Most cleanups after an accident can be done without having to boil the motor. You can use a cloth to clean up after an accident. Use an old toothbrush to break dirt off that is packed in. Use a little nitro fuel to loosen up dirt. Clean all parts and reassemble engine.

Hope this helps

Ken