how do i clean the pistons?

If you have the pistons still in the motor than be very careful as any carbon you remove must n't go down the bores. Bring the piston to the top of its stroke and then use a wooden lolly stick to scrape away the carbon. Dont be tempted to use a wire brush as any scores in the piston head wil affect the engine after re-build. You can try softening the carbon with a little petrol but a wooded scraper will not harm the metal piston. Any debris must be removed before you allow the piston to move back down the bore though or it may score the bore. Hope this helps
regards
Gaz

Gaz
March 2010