Topic: Piston Ring end gap issue?

[rosewood]

I am hoping someone can shed some light on my latest issue with rebuilding my CB550.

I have torn down the entire engine and have begun reassembling everything. The bottom end is now complete with new bearings and chains etc.

Have just started on the top end in particular the cylinders and pistons. My cylinders were measured and were all still within spec and I sent them out to a shop to get them honed/deglazed. After doing some research and people speaking highly of Cruzinimage products I purchased a set of new rings from ebay. 

I measured the endgaps of all rings last night in selected cylinders and found a large variation in endgap measurement especially on one set. I then swapped the rings from my smallest and largest measurement into respective cylinders and found a similar result which is indicating there is a large variation in ring length?  You can see this from the images Ive attached. (I also reversed the order I installed the rings into that one cylinder to eliminate any doubt from anyone whether its a cylinder bore variation)

The spec for ring gap is 0.15-0.35mm with a service limit of 0.7mm.

My measurements so far for the rings Ive 'allocated' for each cylinder is: (top compression ring only)

1: 0.28mm
2: 0.31mm
3: 0.43mm
4: 0.6mm

Sets 1 and 2 seem within spec but 3 & 4 are outside especially 4 with is approaching the service limit.

My question is 'Is this OK?" or should I find a new set of rings which have a tighter tolerance between all rings?

Would I notice any issues with them installed especially from set 4?

I have contacted cruzimimage and am waiting to hear back from them but would like to get opinions from others whether this will be an issue or not or if I'm just being paranoid.

Thanks for reading
rosewood...

[FunJimmy]

I'm a bit anal about specs like this and therefor would look for another set or rings.
Wouldn't want the uncertainty always in the back of my mind.

Here's an interesting article.

http://www.badasscars.com/index.cfm/page/ptype=product/product_id=393/prd393.htm

[Dunk]

Ring gap should be the same on all cylinders. I would not open them all up to .6mm. Typically rings are file fit so gap will be very small initially and you set it, or fairly commonly in factory motorcycle rings apparently is pregapped. I forget what brand rings I used on my CB750 when freshening up the top end but they were pregapped and within a couple thousandths of each other. I just opened up the tighter ones slightly to match and I think I was towards the tighter end of spec.

I would return those and either ask for a file fit set of look for a different vendor.

[kmb69]

Kind of unusual to see that much variation in a set of rings.
Are the gaps the same if you measure them in alternate cylinders?
Sure possible the cylinders were not all honed to the same diameter.

[Lostboy Steve]

I believe those are the rings I am currently running in my 550 I do not remember checking them though or having any figment issues. I will say that at this point, I would at least make them send you another set and see how they are.

[madmtnmotors]

I swapped the rings from my smallest and largest measurement into respective cylinders and found a similar result which is indicating there is a large variation in ring length?  You can see this from the images Ive attached. (I also reversed the order I installed the rings into that one cylinder to eliminate any doubt from anyone whether its a cylinder bore variation)

[rosewood]

Kind of unusual to see that much variation in a set of rings.
Are the gaps the same if you measure them in alternate cylinders?
Sure possible the cylinders were not all honed to the same diameter.

I just swapped the best gap with the worst gap and got similar results in the different cylinders. so my conclusion is that mostly its the variation in rings as opposed to cylinders. I would have expected them to all be closer to the tighter side so they could be filed bigger if required.

I haven't remeasured the bores after honing but it was just a very light deglaze and I doubt they would have taken much if not any measurable material off. I shouldn't assume though but swapping the rings kinda confirmed this.

I believe those are the rings I am currently running in my 550 I do not remember checking them though or having any figment issues. I will say that at this point, I would at least make them send you another set and see how they are.

Yeah that's what I'm hoping for but the prob is I purchased in May so outside the 30 day return policy. I did check one set across all cylinders when I first go them and of course it was set 1 and looked ok so just assumed the rest would be very similar.

If the Cruzinimage doesn't come to the party I'm considering just buying another set from them and hoping I can find 4 that are good across 8 sets.

Any other suggestions or can anyone recommend  another brand to try...RIK possibly?

[kmb69]

Ooops! 
Sorry, I did not read thoroughly.
Sounds like the rings are the problem.

[Dunk]

I assumed he measured the gaps in the same cylinder. He shows them stacked in one jug in the picture and the gaps are obviously quite different to the naked eye. That would have to be some serious taper in that bore... but I'm assuming taper is negligible or was honed out since he just got them from the machine shop. A good idea regardless to measure bores and taper, trust but verify.

[Jerry Rxman Griffin aka MuthaF'er]

OK, so you don't just slap rings in the cylinders without setting the end gaps.

As long as they were ordered correctly and any gap is too large you got what you ordered. File em properly.

[jgger]

I don't know about any one else, but I never check the ring gap that high in the bore. If the measurements were taken where the rings are shown in the pics, then they are not accurate.

I was taught that you place the ring in the bore then push it down with a piston turned upside down from the top of the barrel. Insert the piston until the ring grooves are even with the top of the cylinder. This will place the ring at the top of its travel and set it square in the bore. Now measure the gap. If the ring is even slightly tilted it will give you a bad measurement.

Now if the rings were put in there for only a visual for the picture........then disregard everything I just typed.

[FunJimmy]

I don't know about any one else, but I never check the ring gap that high in the bore. If the measurements were taken where the rings are shown in the pics, then they are not accurate.

I was taught that you place the ring in the bore then push it down with a piston turned upside down from the top of the barrel. Insert the piston until the ring grooves are even with the top of the cylinder. This will place the ring at the top of its travel and set it square in the bore. Now measure the gap. If the ring is even slightly tilted it will give you a bad measurement.

Now if the rings were put in there for only a visual for the picture........then disregard everything I just typed.

Unless the rings aren't square, the depth shouldn't matter. Cylinder walls must be straight. From top to bottom.

[jgger]

That would be true for a fresh bore. The OP said that it was just a hone job, so the bore is slightly tapered. Plus with the rings all the way at the top, they are not being measured in the wear area of the bore. I know, I'm probably picking fly poop out of pepper here, that is just the way I was taught.

That still doesn't answer why the gaps are so varied though. I tend to agree with the others, he got a funky set of rings.

Hey Rosewood, if you order another set from the same vendor you could mix and match to get the best results and then return the goofy set for a refund. I would think the vendor would step up on this and overlook the 30 policy.

Good luck with it though.

[rosewood]

I don't know about any one else, but I never check the ring gap that high in the bore. If the measurements were taken where the rings are shown in the pics, then they are not accurate.

I was taught that you place the ring in the bore then push it down with a piston turned upside down from the top of the barrel. Insert the piston until the ring grooves are even with the top of the cylinder. This will place the ring at the top of its travel and set it square in the bore. Now measure the gap. If the ring is even slightly tilted it will give you a bad measurement.

Now if the rings were put in there for only a visual for the picture........then disregard everything I just typed.

Hey jgger I did measure as you have suggested pushing the ring down with the inverted piston to the last grooves were even with the top of the cylinder...I just stacked them like that for the picture to show the differences..

That would be true for a fresh bore. The OP said that it was just a hone job, so the bore is slightly tapered. Plus with the rings all the way at the top, they are not being measured in the wear area of the bore. I know, I'm probably picking fly poop out of pepper here, that is just the way I was taught.

That still doesn't answer why the gaps are so varied though. I tend to agree with the others, he got a funky set of rings.

Hey Rosewood, if you order another set from the same vendor you could mix and match to get the best results and then return the goofy set for a refund. I would think the vendor would step up on this and overlook the 30 policy.

Good luck with it though.

I haven't heard anything back from the vender yet which sux! Will try again this week but yeah failing that I think I'm going to order another set and cross my fingers I get lucky second time around..

Thanks everyone for your comments..

[754]

You are putting them in used cylinders...so they are probably worn. Some maybe more than others
 If you slip the old piston in the bore, correct way, try sliding a feeler guage in at front or rear, if you get a .003 Or .004 in its probably well worn....... Just off the top of my head..check service limits.

[rosewood]

I wasn't aware there is a check/measurement for the piston in the bore. I will have to read through the manual again. Yes the cylinders and pistons are worn as the bikes done 80,000km. But the bores all measured within spec and the same for the piston skirts. I'm not expecting the motor to be like new when I'm finished just trying to do the best with what I have.

I finally got a response from the vendor saying he will refund the parts which was great, But he's blocked me on ebay now from buying another set! I guess he doesn't want to deal with me if another set gives me problems...

So I'm in a bit of a dilemma now on what to do....Can someone recommend another set to purchase from ebay? Genuine honda are very expensive, especially shipping to New Zealand.

[FunJimmy]

I wasn't aware there is a check/measurement for the piston in the bore. I will have to read through the manual again. Yes the cylinders and pistons are worn as the bikes done 80,000km. But the bores all measured within spec and the same for the piston skirts. I'm not expecting the motor to be like new when I'm finished just trying to do the best with what I have.

I finally got a response from the vendor saying he will refund the parts which was great, But he's blocked me on ebay now from buying another set! I guess he doesn't want to deal with me if another set gives me problems...

So I'm in a bit of a dilemma now on what to do....Can someone recommend another set to purchase from ebay? Genuine honda are very expensive, especially shipping to New Zealand.

What a Dick. He must understand that you require an additional set of rings to finish your build. Surely he'd sell you one more. Right?

If not, I'd get a buddy to order one set then leave negative feedback for being a tool.

[ekpent]

 So he blocked you as a buyer, hmm, reminds me of the Soup Nazi, "No rings for you"   

[PeWe]

Contact eBay and inform them about the problem.

[disco]

Seems like his EBay store has been shutdown. I was hoping to buy an 836 kit.

[kmb69]

Seems like his EBay store has been shutdown. I was hoping to buy an 836 kit.

He is still on eBay but he has no 836 kits listed.
Must have received a bad batch of parts from his supplier and had to pull the listings.
He has NO piston kits listed on his regular .com website. Go figure!

 

[rosewood]

I'm not sure whats going on with him...he wont reply to any messages. He removed the listing I purchased the rings from which was from his 'cruzinimage_au' account.

Still has them listed under his 'cruzinimage_co' account though.


I'm not sure I even want to get a buddy try purchase another set from him at this stage

Can anyone comment on this set?:

http://www.ebay.com/itm/HONDA-CB550-CB550K-CB550F-STD-PISTON-RING-SET-OF-4-1974-1978-13011-374-000-/371724336621?hash=item568c7f3ded:g:lOoAAOSw5ClXxv2U&vxp=mtr

[eigenvector]

Why fool with it - perhaps it's due to the shipping, but you can get Honda OEM rings for  $120 and they absolutely will fit and work for the bike.

It's what I used when I rebuilt the motor on my CB550K and I had no problems, no end-gap issues, no quality problems.

[ekpent]

 Those RK rings are probably better quality than the others. Been around a long time. Made in Japan, did you see where the ones you got were made ?

[rosewood]

Why fool with it - perhaps it's due to the shipping, but you can get Honda OEM rings for  $120 and they absolutely will fit and work for the bike.

It's what I used when I rebuilt the motor on my CB550K and I had no problems, no end-gap issues, no quality problems.

Yes it's due to price and shipping to NZ, I cant even find a genuine full set of 4 on ebay. Most companies charge an over inflated amount to ship anything to NZ. Its hard to jusify paying 2-3 x the amount for OEM.

Those RK rings are probably better quality than the others. Been around a long time. Made in Japan, did you see where the ones you got were made ?

The ones I got came from a buyer in Japan but i have no idea where they are actually made. other members have spoken highly of them before though..