Procedure for re-ring in a plated cylinder

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TheRadBaron
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Procedure for re-ring in a plated cylinder

Post by TheRadBaron »

I'm going to be pulling the top end off my new '89 KDX200 this week so I can service the KIPS. The valves aren't working at the moment so I imagine they'll need a lot of attention. I'm planning to pull the cylinder off so I can clean everything up well and I figure that it would be a good idea to at least install new piston rings while I have the cylinder off. This is of course assuming that the bore is in decent condition. Looking through the exhaust port everything looks pretty good. The piston isn't scuffed and is showing only the slightest signs of blow-by. What little I can see of the bore looks clean. The motor seems to have good compression and sounded good when I heard it run. No piston slap or other suspicious noises.
So if the piston and bore end up looking good, would I be well served to just install new rings on the piston? I know that a new piston kit would be ideal but I'd really rather not spend any money that I don't have to.
I don't have much experience with plated cylinders so I'm not sure what the accepted method or re-ringing is. I know with iron cylinders it's proper to run a hone through the cylinder during a re-ring. This gives the cylinder a crosshatch that helps the new rings break in and seat properly. I've read on this site that plated cylinders should not be honed, though. Will the new rings seat on a well used but sound plated bore? Thanks for the help.
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Joshmcmillan
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Re: Procedure for re-ring in a plated cylinder

Post by Joshmcmillan »

Measure the ring-gap, if it's within spec (up to 0.35mm is new spec, 0.65mm is max service limit, don't quote me).

When I replaced half my power-valve stuff in my 94 I just put it back in as it was within spec. On my 97 I replaced piston/rings while doing the same job. All depends. I don't think I would ever re-ring without replacing piston, but that's just me.
07' CR450X (Main Bike)
07' KX125 (Completed basket case rebuild, for sale)
88' KDX200 (Not sure yet, runs but with rattly top end)
91' CBR250RR
Old Bikes: 97' KDX200, 00' RM125, 85' XR350, 94' KDX200, 02' CR80, 82' XT250, 98' CT200
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KDXGarage
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Re: Procedure for re-ring in a plated cylinder

Post by KDXGarage »

Don't hone.
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