How to clean a Speedfight head and barrel

Q. I’ve just stripped down the head and barrel on my Peugeot Speedfight and the piston is coked up with black crap.

What’s the best way to clean it without damaging it?
Fred1021, MCN forums
 
A. Most of the coke will be on the piston crown and you need to chip the worst of it off with a paint scraper.

Don’t use a screwdriver as it’s all too easy to carve a groove in the aluminium with its tougher, sharper end. Once you’ve got most of it off, use some wire wool, then wash it in petrol.

The piston sides won’t have the same build-up, and it is even more critical that you don’t damage them, so a light wire-wooling and wash with petrol is all they need.