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Scratches on piston skirt

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Trying to marry up wiseco 100mm to LASleeve 100mm sleeve. Cleaned as best I could between honing, but still got some minor(?) scratches on the skirt. Will it hurt performance or life expectancy. I would say they are just big enough to be visible, may possibly smooth out during break in, but I'm not sure. How the hell can you keep checking for clearance and what not without a little scuffing anyway?

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Yeah that's my point. I kept having to put the piston in the cylinder to check the clearance. Grind, clean, check clearance, grind more, clean more, check again, ad infinitum. After a while the skirt got a little scratched.

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I've already finished it. I cleaned it with wd 40 before I put the piston in to check the clearance but I still got micro scratches on the skirt. Only question is is the piston too damaged to use. I know of no other way to check clearance other than put the piston in the cylinder and slide in the feeler gauge. Grind, clean, check clearance and repeat until clearance is right. Prolly should have had it done at machine shop but what's done is done. I used a regular deglazing hone to size the sleeve.

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I wouldn't bother starting that engine. You'll be sorely disappointed at the outcome. Pull the cylinder, bring it to a machine shop, let them tell you if they can salvage your cylinder. Let them tell you what size piston you need now and have them machine your cylinder with that new piston in hand. You can never use a feeler gauge to check piston to cylinder clearance. You need a bore mic or CMM. You must also clean the cylinder with hot soapy water and a sponge before assembly. WD 40 is not going to get your cylinder clean.

Edited by Adamthomas

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I wouldn't bother starting that engine. You'll be sorely disappointed at the outcome. Pull the cylinder, bring it to a machine shop, let them tell you if they can salvage your cylinder. Let them tell you what size piston you need now and have them machine your cylinder with that new piston in hand. You can never use a feeler gauge to check piston to cylinder clearance. You need a bore mic or CMM. 

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Thanks Adam. Hopefully the piston is not too damaged and there is enough left on the sleeve to machine in correctly. First time ever engine rebuild. I thought I did enough research but I guess not. Now if you'll excuse me I'll go jump off a cliff.

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Don't panic, grab a beer.

Back in the day when I had no money I did the same thing and the bike ran fine.

Maybe I was lucky.

Put up a picture of the piston and the cylinder. Unless you used a hammer to put the piston it is prolly still salvageable.

But then again maybe it isn't.

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Well, with the crude equipment that I have, the bore is out of round somewhere on the order of one or two ten thousandths of an inch and roughly the same for taper up and down. And now that I think of it, piston to wall clearance, feeler gauge wise, should measure about twice, one feeler leaf on opposite sides of the piston, what the specs call for. So I still have about 3 thousandths on the sleeve that need to be removed. If I'm right about the roundness and taper, it should be correctable

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Get it measured correctly. I don't see a crosshatch either. It could be my phone but I should still see it. It shouldn't be that shiny.  We all make mistakes, that's what I like about this forum, we all help each other!

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400 grit meaning that I used a really fine stone to finish it, so the crosshatch is there, it's just hard to see.

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One more question about piston to wall clearance. Am I correct in assuming that a 3 thousandths clearance is a circumferential clearance? Meaning that diameter wise it would translate as a 6 thousandths difference between cylinder diameter and piston diameter?

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