carbon is what a by product of burning fuel now there can be a excessive buildup as running it rich too long but when u take your piston out you loose where your rings were seated so then u need new rings and need to hone the bore to get a smooth linning for the new rings to reseat .
the trick is tune your engine perfect and get a oil like castrol active 2t or one with a little cleaning agent in it and not run it rich and carbon should wear away .
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