Dawn power dissolver removes gunk and light rust from bearings and engine internals too.

I've done this on close to a dozen engines, some which were tossed out because the engines seemed frozen or caked with so much dark junk that the owners tossed them out.

I pull the backplate off and remove the glow plug.

I'll then rinse the engine in hot water to help loosen things, then shake out the water.

Next I'll liberally apply Dawn power dissolver to both the outside and inside and let the engine sit for about 3-8 minutes to let the chemicals do their work. Note: if you have an anodized head, keep the time involved down to 2 minutes as more will remove the coloration.

Again the engine is rinsed in hot water and I apply another liberal dose of Dawn.

On the subsequent application(s) I'll use a small brush to get at difficult to reach areas in the crankcase while working the piston around slowly to exposed other areas.

A few repetitions may be in order for the inner surfaces.

For the outer surfaces I'll use a plastic dish scrubber to free up what remains until the engine looks shiny and new.

Again the engine is rinsed with liberal amounts of hot water.

Next I shake out all of the moisture I can, and I'll flush the engine out with WD-40 to further free the bearings and dislodge any gunk.

Finally I'll use a rinse of old but clean glow fuel to get rid of any remaining water.

At this point I'll normally check the bearings, move the piston up and down, looking for any "grittiness" or clues that the bearings may be scored or damaged. If the engine turns over smoothly it is left to dry for a day or two, then re-assembled.

I'll also check that all of the nipples and needles are clear and that I can blow air through the needles.

With about half a dozen of these engines they have started right up on the first try.