Topic: Do I need to replace my rings?

[TheHulk]

Hi everyone. A bit of a philosophical question. I am in the midst of rebuilding a CB550F. I decided to take apart the top end of the engine to check for general wear and tear, do some cleaning, and replace the gaskets. The Pistons had a little bit of carbon buildup, but nothing that a little hand scrubbing and dremel-ing couldn't take care of.

I have been debating on whether or not to replace the rings. The cylinder walls are smooth with no visible scratches or marks. I keep thinking that I MIGHT AS WELL since the rings are most likely original, I have the engine taken apart this far, and the engine has 34k miles on it. Despite the high miles, everything looks like it's in good shape.

This is my first rebuild, but luckily I have a friend who has rebuilt the same bike. He insists that the rings are fine and I shouldn't worry too much about it. I didn't run a compression test before disassembly because everything seemed within decent working order. I would love to skip putting the new rings on, but I don't want to be kicking myself for not doing it in the near future.

SO. Should I replace the rings? If I do, will I have to get the cylinders honed (not bored)? Because of the COVID outbreak my local shops are mostly closed, and I do not have the tools to hone the cylinders properly and I'd like to avoid doing any damage by going the diy route. If I were to put new rings on without honing, would that defeat the purpose or cause damage? Is the purpose of honing to break in the new rings?

Apologies for the many questions. Thank you for the help!

[marko59]

Yo! I vote no. Naturally had you gotten some compression numbers prior that would help. My 550 has abt 25 k and I just did the same thing. My compression prior was terrible. But it was a crap gauge. With a motion pro gauge it was all 170. My cylinders looked just as you’re describing. I’d leave it be if you’re happy with how your bike runs. Once you go into the motor you see how easy it is if need in the future. Put it back together, use good ( cosmetic or Honda) gaskets and Gaskacinch sealer on them. Good luck.

[samm_j2]

I would say to  get new rings and hone the cylinders, why not if you are this far in there? you may need to do a bit of a break in after rebuild but again if you have the motor that far taken apart I would go for it.  Curious as to what some of the other guys with decades of experience have to say about this.

[bryanj]

DO NOT put any sealer on gaskets, they dont need it.

You could carefully remove a ring and check gap in bore but i strongly suspect it will be fine.

Hondaman on here has advice on using slightly oversize O rings as modern gaskets are thicker.

On building make sure ALL debris is removed from oilways and jets(especialy jets in base dowels and oilways to them)

Read, re read then read again the manual on fitting valve cover, its very easy to bend valves on reassembly and once more NO GASKET GOO OF ANY KIND

[TheHulk]

DO NOT put any sealer on gaskets, they dont need it.

You could carefully remove a ring and check gap in bore but i strongly suspect it will be fine.

Hondaman on here has advice on using slightly oversize O rings as modern gaskets are thicker.

On building make sure ALL debris is removed from oilways and jets(especialy jets in base dowels and oilways to them)

Read, re read then read again the manual on fitting valve cover, its very easy to bend valves on reassembly and once more NO GASKET GOO OF ANY KIND

Thanks! Will do. Why no sealer?

[bryanj]

Because the slightest bit that gets into an oil way blocks flow to the cam and you end up needing everything above head joint

[Jerry Rxman Griffin aka MuthaF'er]

Because it is NOT needed

[Stev-o]

SO. Should I replace the rings?

When I rebuild a motor, I typically have the cylinders measured at the machine shop and then we decide if we need to hone and re-ring or bore [and install oversize pistons and rings].
I've gone both routes, the latter can get expensive.

I have Wiseco pistons in at least 3 bikes, here is some basic info on the process of honing, which will "deglaze" the cylinder walls.

https://www.revzilla.com/common-tread/cylinder-preparation-explained

Are you familiar with ring gap?  Check this thread ....

http://forums.sohc4.net/index.php?topic=161003.0

[HondaMan]

In the case of the 500/550, don't replace the rings if all you've done is slide the cylinders off: they will re-seat themselves to their wear seats again after 1000 miles or so. If you replace them with new rings, they will never seal again. I've explained it many times, but that's the 'short story'.

[TheHulk]

In the case of the 500/550, don't replace the rings if all you've done is slide the cylinders off: they will re-seat themselves to their wear seats again after 1000 miles or so. If you replace them with new rings, they will never seal again. I've explained it many times, but that's the 'short story'.

Thanks! I am convinced. I'll skip the ring job. But! Would it be advisable to remove the cylinders, replace the gasket underneath, and slide the cylinders back over the pistons? I have the gasket in my engine rebuild kit and figured I might as well replace it. Would this effect the way the rings re-seat?

[Tracksnblades1]

Hulk,

If your 550 has the 3 piece oil rings, I would be sure they're not worn down to the expander.

I personally don't like rerings, glaze breakers, worn piston ring lands or bead blasted ring lands, and tapered cylinders...none of which will ever pass a leak down test...

I would compare what you have against Honda's original specifications Limits...

It'll be warm before you know it..😇

[dave500]

ive pulled plenty of 500/550 down,re used the rings and pistons without honing,i do clear the oil control holes in the piston though,they always have some crud in them,just hand spin a drill bit through them.

[bryanj]

If you have the head off you have released preasure on the base gasket plus there are 2 O rings in there to replace so yes remove cylinders.
The tiny oil restrictor jets are part of the dowwls that locate cylinder to crankcase make sure NO debris gets into those holes

[steeldoncb550]

SO. Should I replace the rings?

When I rebuild a motor, I typically have the cylinders measured at the machine shop and then we decide if we need to hone and re-ring or bore [and install oversize pistons and rings].
I've gone both routes, the latter can get expensive.

This is why I measure my own with a caliper at the top and bottom of the cylinders as deep in as my calipers will go. I don’t trust machine shops they might say you need to bore when you don’t.

[Stev-o]

SO. Should I replace the rings?

When I rebuild a motor, I typically have the cylinders measured at the machine shop and then we decide if we need to hone and re-ring or bore [and install oversize pistons and rings].
I've gone both routes, the latter can get expensive.

This is why I measure my own with a caliper at the top and bottom of the cylinders as deep in as my calipers will go. I don’t trust machine shops they might say you need to bore when you don’t.

While I agree not to generally trust shops, my shop is just a "guy" that has a shop in his back yard, and has worked on at least 5 motor rebuilds for me [honing, boring and valve jobs].

He does it right, never an issue...yet.

[bryanj]

Finding that type of person is rarer and rarer now, so much so i just spent loads on a boring bar

[TheHulk]

In the case of the 500/550, don't replace the rings if all you've done is slide the cylinders off: they will re-seat themselves to their wear seats again after 1000 miles or so. If you replace them with new rings, they will never seal again. I've explained it many times, but that's the 'short story'.

Hey Honda Man! Sorry to keep poking the bear, but I have another question. I just removed the Pistons and quickly checked the Top Rings in Cylinder 1 and 2 respectively. The largest feeler gauge in my set is a .025in. That slipped in and out of the end gap quite easily, I was thinking to myself "that must be about .027 or .028".

Just quickly checked my Clymer manual and it suggests that the ring end gap wear limit is .028, which seems exactly where it is. Do you still suggest skipping the new rings? Would you mind elaborating on why new rings wouldn't seat/seal properly?

Thanks man!

[HondaMan]

In the case of the 500/550, don't replace the rings if all you've done is slide the cylinders off: they will re-seat themselves to their wear seats again after 1000 miles or so. If you replace them with new rings, they will never seal again. I've explained it many times, but that's the 'short story'.

Hey Honda Man! Sorry to keep poking the bear, but I have another question. I just removed the Pistons and quickly checked the Top Rings in Cylinder 1 and 2 respectively. The largest feeler gauge in my set is a .025in. That slipped in and out of the end gap quite easily, I was thinking to myself "that must be about .027 or .028".

Just quickly checked my Clymer manual and it suggests that the ring end gap wear limit is .028, which seems exactly where it is. Do you still suggest skipping the new rings? Would you mind elaborating on why new rings wouldn't seat/seal properly?

Thanks man!

Well, the whole story is this: the outer 2 cylinder (1 and 4) are overcooled on these engines, due to the air passing over those (oversized for cosmetic reasons) fins at about 10 o'clock on #1  and 2 o'clock on #4. This caused those portions of the cylinders to expand less far away from the pistons when hot, making the rings there wear more than the rest of the way around the piston. This then caused them to stop rotating around the pistons, too. The holes eventually became egg-shaped, with the blunt end toward those o'clock positions I mentioned above, and non-round. On the 750 the center 2 do this, too, toward the cam chain tunnel: it takes about 40,000 miles on the 500/550 for those to distort that much, though.

So, the holes are no longer round. If you put the old rings back in without moving them, they can often find their way back (if the pistons are clean) within about 1000 miles, and things work out OK except for some lost HP. But, the steel liners and aluminum-zinc fins are now heat-relieved and cured, and will not migrate like this in the future. So, boring even one step size restores round-forever bores and can yield more than 100,000 miles of use without significant wear: I have seen it with my own hands many times. You also get back all the original HP plus a little more, and it will stay forever.

[PeWe]

A quick surface fix with flex-hone brush grit 240 will not remove much material. Measured a cylinder with hole micrometer before and after, very small difference. 10-15  strokes with a brush lubed with WD40.
The brush had been used before with motor oil as lube.

[TheHulk]

[/quote]
Well, the whole story is this: the outer 2 cylinder (1 and 4) are overcooled on these engines, due to the air passing over those (oversized for cosmetic reasons) fins at about 10 o'clock on #1  and 2 o'clock on #4. This caused those portions of the cylinders to expand less far away from the pistons when hot, making the rings there wear more than the rest of the way around the piston. This then caused them to stop rotating around the pistons, too. The holes eventually became egg-shaped, with the blunt end toward those o'clock positions I mentioned above, and non-round. On the 750 the center 2 do this, too, toward the cam chain tunnel: it takes about 40,000 miles on the 500/550 for those to distort that much, though.[/quote]

Wow! Got it.

[/quote] So, the holes are no longer round. If you put the old rings back in without moving them, they can often find their way back (if the pistons are clean) within about 1000 miles, and things work out OK except for some lost HP. But, the steel liners and aluminum-zinc fins are now heat-relieved and cured, and will not migrate like this in the future. So, boring even one step size restores round-forever bores and can yield more than 100,000 miles of use without significant wear: I have seen it with my own hands many times. You also get back all the original HP plus a little more, and it will stay forever.
[/quote]

So I did remove the pistons and I'm sure the rings rotated a bit since they have been out. Will the "egg shaped" rings cause any damage if they do not return to their wear positions? Or will they find their way back in 1,000 miles as previously mentioned?

Or, would you advise that because now that the warping has taken place and is now cured, to take the opportunity to re-round the cylinders which could actually give me better longevity and performance?

Thanks man!