CB550K3 oil control ring problem.

[Ashdowner]

Need help again with my 550 build. Just got some new rings from DS for my CB550K3 with standard bores. The two top ring gaps are fine. The oil control rings (top and bottom) fit in the bore and the gap is fine - as long as the spacer isn't there. Put the spacer in and there is no way they fit the bore, either using the old spacer or the new spacer. The problem seem seems to be twofold. Firstly the new rings are 2.24mm thick whereas the old ones were 1.94mm (so I'm assuming they've worn down). Secondly, the internal diameter of the oil-control spacer is not the same as the diameter of the ring groove, i.e. with it's end butt jointed it actually holds the rings out from the piston and doesn't allow them to compress enough to get them in the bores -that was also true of the old spacer but of course with the thinner rings the pistons fit in the bores. The logical answer is that I have to gap the spacer such that it is a snug fit in the groove and allows the rings to fully compress. Is that indeed the answer please because I've never encountered that before? I'm also surprised that the existing oil control rings are 03mm thinner than the new ones from DS because if they've worn down from the original new size then as I've now found out the pistons wouldn't have gone into the bores. Surely nobody could have shaved 0.3mm off the circumference of the rings

[Nurse Julie]

Could it be that the spacers supplied by DS are incorrect ?. Are they OEM or repro / replica ?

[Ashdowner]

I doubt it, because the spacers are the same size as the old ones that were in. It's such a strange situation when you find that the only reason the old rings fit in the bores with the spacers was that they  are much thinner than the ones I've received from DS. That's why I ask if the logical answer is to gap the spacers so they match the diameter of the groove.

[Ashdowner]

Where's BryanJ when you need him?

[Bryanj]

never had that problem, sounds to me that they may be incorrect to part number

[Ashdowner]

The rings are pattern. Spacer goes in first, then bottom oil ring then top oil ring. The grooves are spotlessly clean. I also am thinking the rings are wrong, because I can't imagine that a ring has worn down from 2.14 to 1.92mm thick when the other rings show no such dramatic wear.

[Bryanj]

I agree, that would be a fantastic amount of wear

[Ashdowner]

The rings are Japanese Riken. As the old and new spacers are exactly the same size, and as the old 1.92mm rings work with both spacers, the logical explanation is that the rings I've received from DS are wrong. Exchanged lots of e-mails with DS today and hopefully tomorrow they'll mount the rings on a piston and prove that I'm either right or as mad as a hatter.

[Ashdowner]

Now sent the new rings back, including one of my pistons with the new oil control rings fitted to demonstrate the problem,and the existing rings to show DS the difference in width. DS thinks that Riken have possibly packed the wrong rings

[Trigger]

Now sent the new rings back, including one of my pistons with the new oil control rings fitted to demonstrate the problem,and the existing rings to show DS the difference in width. DS thinks that Riken have possibly packed the wrong rings

I have used Riken rings for many years and never had a problem. Saying that, I have used DID cam chains for many years also and the other month I was trying to fit a DID chain to a 500 four and there was no way the chain would go on the sprocket. Turned out that it was a 84 link chain and the 500 has a 88 link chain. Never believe the packaging 

[Ashdowner]

DS confirm that the oil control rings are correct but that they can only be inserted with ring compressors because of the force required to compress them. It strikes me that with the spacer compressed and pushing against the rings they must exert a mighty force on the bores. People have been telling me that they've been inserting CB550 rings by hand, but they must have fingers of steel to do it.

[Nurse Julie]

Not sure about that......i can get them in using my fingers without chipping any nail varnish !!!

[Trigger]

Something not right, as the oil ring is the easiest to get in the bores. Is it a one piece of 3 parts ?

[Ashdowner]

It's 3 parts. Spacer and top/bottom rings. Outside the bore, with the rings in the grooves and under pressure from the spacer, they jut out from the piston about 2mm. To compress them down to cylinder size involves also compressing the metal spacer and I've tried to do it by hand with the piston away from the bike, and ok I'm not superman, but it's impossible. (Tells me I won't be doing any arm wrestling with Nurse Julie if she can do it by hand). The real issue to me though is that the rings I've taken out are much thinner than the new ones and I'm struggling to believe they could have worn down 0.3mm. Hence I was asking if someone had some rings lying around that they could measure for me.

[Nurse Julie]

What measurement do you want, thickness and depth?....oh, and I have very small hands. Vernier and rings ready in a mo