Ralph, Iheat the parts to about 100* then spray liberally with the power dissolvere. Ilet it sit for about 20 to 30mins and then scrub it off with a stiff nylon bristle brush, not a tooth brush. Some parts require a second or maybe a third application to get the stubborn carbon off. 4 strokes are harder when trying to clean the intake and exhuast ports but using qtips and successive applications of the Dawn they too can get very clean.

Here's a Saito Idid for a friend. It was in very bad shape. It needed bearings, conrod, prop hub and gaskets.
MK
Before

After