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Are OEM rings File-to-Fit?

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Are the rings that come from Honda OEM, file to fit? I am getting ready to tear my bike down and want to know if I am going to be filing rings (no big deal).

I did a search, and only found that aftermarket rings and OEM rings seem to be all over the place and people are re-ordering rings? :confused:

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I did not need to file the rings on my 05 when I put new ones on.They were OEM and measured good right out of the box!

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I did not need to file the rings on my 05 when I put new ones on.They were OEM and measured good right out of the box!

What clearance did you get out of the box?

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I've done 25 or 30 piston/ring replacements on the crf450. Don't file the rings, they'll fit the way they come.(stock piston/rings) The compression ring is a-symmetrical and has a letter stamped near the break, make sure the stamped letter is facing the top of the piston (per honda manual). The first 26 or 27 were done without reading the manual. I was bored one day and decided to read the repair manual while sitting in a traffic jam, and found this little tidbit of info. I now suspect installing the compression ring upside down will lead to excessive engine oil blow by via the crank case breather.( no discernable power loss) I say this as this was the only variable in my piston replacements over the last few years, and some times they would spit oil out the breather tube, and sometimes they would not.

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they may fit, but the correct way is to check them and file to fit.

if the clearance is correct, dont file, if it is incorrect, file till it is, simple.

only one way to know, you need to check.

installing a ring upsidedown, obviously a no, no.

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Yep, check it.

Generally, plated cylinders have such a consistent bore that filing will be unnecessary. Boreable cylinders almost always need filing, a piston/cyl clearance of .002 will yield a considerably different ring end than .003 will.

That being said, always check.

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There is a chamfer on the inside of the compression ring. It will always go up regardless of who made the ring or what fourstroke engine you put it in.

The chamfer is there to prevent that edge from binding in the land when the ring flexs in the land duing a power stroke. It also aids ring seal by giving compression gases a place to fill and push the ring toward the cylinder.

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What clearance did you get out of the box?

Mine were right on with the service manual measurements. Top ring .045mm and both oil rings were .90mm

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Yep, check it.

Generally, plated cylinders have such a consistent bore that filing will be unnecessary. Boreable cylinders almost always need filing, a piston/cyl clearance of .002 will yield a considerably different ring end than .003 will.

That being said, always check.

The nickle plating on these bikes is so thin I don't think it's boreable, if the jug is out of spec I would buy a new one oem is only $100. Is there still a manufactuer using boreable cast iron blocks out there?

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The nickle plating on these bikes is so thin I don't think it's boreable, if the jug is out of spec I would buy a new one oem is only $100. Is there still a manufactuer using boreable cast iron blocks out there?

You missed the point.

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