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96 xr250r piston rings install rebuild Help!

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Have the engine apart... But I am kinda stopped and need some help.

I have done this job a few times before ( xr350r, xr600r), but before I spend the time to put it all back together, I want to make sure I make the right Choice.

So Far:

I ordered new std. rings and checked them in the old cylinder for End Gap clearance.


Top ring: .020 (Should be .006 - .014) Out of spec! :worthy:

Middle Ring: .016 (Should be .012 - .020) OK:thumbsup:

Oil Rings: .025 (Should be .010 - .030) OK:thumbsup:


Should I not worry about the top ring being a little of service limit ( spec)?

Just put it back together?

Do you think this rebuilt engine will smoke ? Or none at all?

Other ideas??

Note: I don't want to much $$ into it..... THis is a back up bike.

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I would not reassemble the engine based only on the ring end gap measurements. Per the service manual, I would measure the cylinder bore diameter and the piston diameter. If they are out of spec, a rebore is in order.

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The ring gaps indicate cylinder wear so as the previous poster said more measurements should be done to verify piston and cylinder condition. You can check cylinder taper by measuring ring end gap at several locations.

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is there a 'lip' where the rings stop on the barrel? If so then there is wear and you may need a rebore which will mean new piston and oversize rings (and with it new piston pin and pin clips).

You already have the new rings so I reckon you ought to just put them in and see how it goes - worst case (if it smokes) you will need to rebore it anyway so you will only be down the cost of a cylinder head gasket and base gasket.

Ideally you should take the glaze off the bore before running the new rings (this helps them bed in and seal better). So as to not lose too much metal off the barrel, I would not reccomend using a proper honing tool. I usually just use a piece of 800-grain wet/dry paper and VERY LIGHLTLY make a cross-hatch pattern by moving the paper in alternating left-right diagonals along the barrel length. Do not forget to lube the barrel and the paper liberally with WD40 or similar prior to doing the DIY hone.

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