Bird76Mojo gave the advice of using Seafoam to help soften up carbon deposits on the piston and head. You can see pictures of my using it on my engine here
I used a Dremel tool with a brass cup brush to speed things along, but I'm sure a wire hand brush would work well, too.
Hope this helps.
Not wanting to sound ungrateful about the Seafoam tip because I really was going to get some, but...
I was just killing some time today and decided to try cleaning the pistons with a degreaser I had laying around. This is my first time around this block so I don't know how you experienced guys would classify the build-up on these pistons. But they seem to have cleaned up pretty well...yes or no?
But what about those striations on the sides? Bad? Normal? Something to worry about?
The scratches on the top were already there...I don't guess they're a big deal?
Oh, by the way, the degreaser was 'Zep professional strength, heavy duty, citrus degreaser' and it not only cleans it leaves your parts with that fresh citrus-y scent.
It looks pretty good to me but I'm not sure what I'm looking at either. Some very slight striations doesn't seem to be any build up. By build up I assume you mean does it look like any of the metal from the piston was transferring to the cylider walls. If that's what you mean, then I don't see that.
He's asking because the skirts of those pistons looked pretty scuffed. They almost look bad enough where I probably wouldn't use them. Typically if the pistons are that scuffed up the cylinder bore is going to have problems. Can you get some good shots of the inside of the cylinder bore?
Yeah, anything you fan feel with a fingernail dragging across it is time for a hone job and new rings if not a bore job plus new pistons. What I'm looking at there qualifies for a good hone job at the very least.
That said, I have stuff with engines in way worse shape than you that still run hard and reliably. The thrust side of one of the cylinders in my main scooter has about 1/8" of missing metal due to extensive wear. Compression is pitiful, but the thing still raps out and sends me down the road at near factory speeds.
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