Help Piston ring marks

Hi, im rebuilding my first xs650 engine. Its a 477 with 0.25 pistons.

The LH cylinder was burning oil, and on inspection the LH cylinder has some ring marks. You cant feel a edge on the marks and I've done 30 seconds of honing but don't know how much I can do.

Can I have advice on what to do.

Thanks Ken

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supercooper04 said:

Hi, im rebuilding my first xs650 engine. Its a 477 with 0.25 pistons.

The LH cylinder was burning oil, and on inspection the LH cylinder has some ring marks. You cant feel a edge on the marks and I've done 30 seconds of honing but don't know how much I can do.

Can I have advice on what to do.

Thanks Ken

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Those lines/craters/cavities need to be completely removed for proper ring seal. A 447 w/ .25 over slugs? Are you replacing stockers with 0.25's, or they're already there and you need to step up to the next size? Either way the pistons need to be measured and the bores matched to them. If the bore is already at the limit (or close) with the current hone job, You'll need a bore job and the next oversize piston set.....honing to the next size takes forever, wears out the hone quicker, and is less accurate than a boring bar.

Yes, that needs a rebore. Just how much is the question. If the pistons that came out are marked .25 on top, they are first over pistons.
The only way to know for sure how worn they are is to measure the bore on that cylinder. Most machine shops don't charge much to do the measuring.
Leo

The engine already has .25 pistons inside the engine. I dont have any history on the engine.

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hi that needs a rebore , you will need to get new pistons first ,so the engineer can match the bores to the pistons ,but take the jugs first and they will tell you which oversize to get, I had the same as you, but had to go to 0.75 to give him some room to work with. good luck with the rebuild