<HTML> On a cast iron cylinder exhast ports I use any tool that will scrape off the carbon. just be careful not to go crazy and scratch the bore or nick the edge of the port.
On the top of the piston, I use that wonder drug W4 Diddly (WD-40) and one of those green pot scrubber pads like a ScotchBrite. They will not harm the metal. Put the WD on the carbon and let it sit for a couple of minute til it softens it up
After doing the pot scrubber number, you will see that the piston dome is very smooth. Get a little aluminum polish and polish the top of the piston to a mirror finish. After using the polish be sure to remove all traces of it by buffing with a clean rag and cleaning with carb spray. I like STP in the red spray can. Next time you decoke, the job will be easier.</HTML>