Piston Ring Question

5 replies to this topic
  • bigtooth

Posted April 01, 2006 - 07:21 AM


I'm installing a new piston and rings in my 1991 xr 600r and am unsure about a couple things:
a. Which ring is the top ring? There is a chorme looking ring and a dark cast iron loooking ring, then the oil expander and the to oil rails. But I'm not sure which one of the first two is the top and which is the middle.

b. On the oil ring expander there is a piece of wire that spans the gap, it looks like its crimped to stay in the expander. One side of the gap slides over the wire and the other is fastened to the wire. I just wanted to make sure that this is meant to stay in the expander or if it should be removed, because the pictures in my manual do not show this or describe it.

any help would be great.


  • roadcam

Posted April 01, 2006 - 07:48 AM


the shiny ring is your top ring, the dark one is the second ring ... if you see a mark on the ring towards the end gap, that goes 'mark'-side UP ... dont forget to stagger your ring end-gaps around the piston ... I have never seen an oil control ring with a wire in place to hold it together ... I would suggest it is possiby for packaging, but better check with someone more knowledgable on that one ... :thumbsup:


Posted April 01, 2006 - 03:27 PM


Yes the wire stays in the oil ring spacer and the oil rails fit over the edges. I don't know if you have a fresh bore, but you should always check your ring end gaps by placing each ring down into the bore and check the gap with a feeler gauge. You can use the piston to push it down a few inches from the top and align it square in the bore. If they are too small, you will have to file one end until you get the proper minimum gap. Remove the ring from the bore when filing. File one end keeping it square. Then check it back in the bore again. If you are using the old bore it's possible you will already be on the big side of the gap. There is nothing you can do about this. It will just have a bit less compression and might use a little oil. I don't have end gap specs for the 600 only the 650L. The difference in bore size is minimal so I wouldn't think there would be any difference. Here's what I have:

Top Ring gap: (0.008"-0.016")
Second ring gap: (0.014"-0.022")
Oil ring side rail gap: (0.01"-0.03")

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  • bigtooth

Posted April 02, 2006 - 07:53 AM


Thanks for the replies and the great info, I've got the cylinder and the head back on and am now unsure about the cam chain tightener. I dont have the special tool that compresses the spring, and i'm not sure if the arm of the tightener is supposed to connect the with the chain directly or if its supposed to put pressure on the intake side cam chain guard. Any advice would be appreciated and thanks again for the info on the rings.


Posted April 02, 2006 - 06:01 PM


Oh yeah the special tool. I think I used a pin punch that fit tight in the small hole in the arm and tied it off with a piece of wire to hold it back while I installed the chain. The tensioner arm pushes on the back of the tensioner/guide. Be sure and get the cam timing correct. Good luck.

  • cleonard

Posted April 03, 2006 - 08:43 AM


I tried the pin punch method the first time. It broke off in the hole. :thumbsup: Then I used to do the put a wire around the spring method. Install chain and cut off the wire.

Now I just take the right side cover off and press against the rear guide to push the tensioner back. It's not too hard. Plus, with the right side cover off, it is a lot easier to get the cam chain back on the lower sprocket. It always seems to want to come off.

The tensioner wears out pretty quickly. If the piston was worn out the tensioner most likely was too. Not too expensive. Mine seemed fine when putting the bike together, but didn't work when the engine was running. When it was hot the chain got loose and slapped around making quite a racket. Replaced the tensioner (and chain) and the engine got quieter.

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