Topic: CB500K Piston Ring Question

[Dr. Frankenstein]

So I 'm trying to put my '72 CB500K back together, vapor blasted the pistons so they're nice and clean, got some new piston rings from 4into1 and found out the oil ring(s) don't seem to fit - one ring and the oil ring (that crenellated ring) fit fine, but the other ring seems to make it too tight to fit, they are too 'thick'. The old rings measure 0.45mm thickness, the new rings measure .50mm thickness. Times TWO (top and bottom rings)that's a whole millimeter

4into1 reports that they have received no reports of problems with the new rings fitting standard CB500K pistons, which is what I have. The pistons measure 55.56mm, and OEM rings according to the parts diagram are 13011-323-014, which is what they sent me. According to 4into1 'we haven't had any previous problems with fitment'...and the part # they did send me DOES match up with useable rings in the parts diagram (illustration #5 in the lower left corner)  - so what am I doing wrong with their install? I've worked on plenty of engines before and never had a problem with parts-matched parts - is it me...?

The oil ring on the left is the new one, the ring on the right is the old one. The problem I'm having is with the 'sandwich' rings...and both the old oil ring and the new one mic out at 2.5mm, IIRC...
   

[newday777]

4into1 doesn't sell Honda parts. They sell aftermarket Chinese made parts.

[scottly]

Are the new rings supposed to overlap protrusions on the sides of the expander?

[Dr. Frankenstein]

Not sure what you mean - I have no ring expander tool, but measured the ring gap in the cylinder and that spec'd out okay, but the new rings don't seem to want to 'channel' above or below the crenellated oil ring on the piston itself, i.e they don't seem to want to fit into the piston groove - ONE will, but adding the second seems to make it too tight, it won't rotate in the channel. I think (1) either they are too 'thick', or (2) I'm not putting them in right. As mentioned, the original OEM upper and lower rings spec out at .45mm thickness, while the new rings (disregarding the crenellated oil ring) measure .50mm thickness. 4into1 says they haven't had any previous reports of ill-fitting rings for this bike (1972 CB500K)...and yet...

Maybe it's me...? Newday777, where do you buy your parts from...?

[scottly]

The expander is your "crenellated" oil ring.(I had to google the word)
I think the answer is #2.

[Dr. Frankenstein]

Oh, right...! And No, they don't. I looked at them with a magnifying glass...they're just tight...I thought they would just slide/pop right in, but maybe I'm missing something...?

[scottly]

Please post some close-up pics of the expander.

[Dr. Frankenstein]

See above - how close do you want me to get??

[scottly]

Close enough to see the details where the expander would contact the sides and bottom of the groove in the piston.

[Little_Phil]

Never seen a central oil ring like that.
I have sets of original Honda rings.
Central wavy ring 2.30mm The two two thin rings 0.45mm

[Dr. Frankenstein]

Yes, those are the measurements I got too, on the old ones...on the new ones 4into1 sent me, I got 2.3mm for the oil ring, and .50 for the two thin rings...and that 1mm difference (for the two thin rings) makes it too tight to fit.

4into1 is telling me -   

"Thank you for contacting us.

We had a look at some of our rings on the shelf here in our warehouse and they all measure the same as the set you received. That said, with these measurements in mind, we have not received any reports of fitment or performance issues regarding these rings when used on stock pistons for the CB500k 1971-1973 model years.

Thank You,
Jason Rundle
4into1.com

...so I don't know if it's ME, or the rings...

The CB500 parts diagram shows three different part numbers for those rings - 13011-323-003, 13011-323-0013, and 13011-323-014 (which is the one they sent me).

After doing some digging around online, part number 13011-323-0013 looks like the rings I received, but that is ALSO listed as a replacement for the 1971-1973 CB500...the old oil ring(s) I took out though does not look like the new oil rings they sent me - note the different "STD" part numbers...but according to THIS, they should fit...so I don't know. I'll probably just return them and try another part number, IF I can find one.

[Oddjob]

A genuine set of Honda rings will cost you around $50 a set these days, CMS still sell them BUT be aware they are claiming they are genuine but they aren't. They'll send you brand new boxed Riken rings instead, with a Honda part number sticker stuck on the box, not a genuine Honda sticker, one they've printed. To me that's an aftermarket part, not a genuine part in a genuine Honda box, as such they should be FAR cheaper. Ok, it's the same manufacturer but so are Koyo bearings or NTN when you buy them at the bearing suppliers and they are less than half the price of a genuine Honda bearing. I complained to Honda when they sent me Riken rings when I'd paid for genuine, they passed it onto to Honda Europe and that's as far as I heard about it.

4into1 are $9.95, the price reflects the quality, send them back and either bite the bullet and find some genuine rings or use Cruzinimage and buy a set of theirs, still not as good as genuine but far better than that crap they sent you.

https://www.ebay.co.uk/itm/285118937548

[Deltarider]

I don't recognise the picture you present of CMSNL. BTW, I have seen the name 'Riken' mentioned in genuine Honda parts lists between ( ). I get the impression of a customer, sour after having speny some money and now blaming CMSNL where you have no reason.

[Oddjob]

That's odd Delta as I did a post on the subject on the UK site, so surely you saw that.

I did an official complaint to Honda UK, you cannot advertise parts as genuine Honda and then send something else, even IF they are made by the same manufacturer as the original part, they are still doing it now and CMS tried to say the parts were genuine when they are not, in Riken boxes not Honda, no official parts label, just a made up one. Whether you recognise that is of no interest to me https://www.cmsnl.com/honda-cb550f2-super-sport-550-four-1977-england_model17121/ring-set-piston_13031374000/ I fail to see one mention of Riken in that link.

[bryanj]

The original scraper ring was a one piece part, then if you read the parts book carefully there are two different suppliers of ring sets, one is Rikken and i cant remember the other as i am away from my books on holiday but both fit the Honda piston, usually made by Art
2nd supplier was Nippon and Riken is correct spelling

[HondaMan]

I am more concerned about your having blasted the pistons: this reduced the OD of the piston skirts slightly, which will likely introduce piston slap, at least on cylinders #1 and #4. It will also promote oil consumption. 

[Dr. Frankenstein]

No, I thoroughly researched that too; I'm using 170# fine glass bead which is almost like talcum powder, not regular sand blasting medium. Plus I always rinse everything out thoroughly and use pressurized air to blow out all the passages, then go in with Q-tips or the like to make sure every binding area or surface is scrupulously clean. There's a lot of videos and information on the subject on the Interwebs.

[bryanj]

Trouble is most of tinterweb is talking car stuff not the super close tolerance Honda motorcycle

[Deltarider]

Trouble is most of tinterweb is talking car stuff not the super close tolerance Honda motorcycle

Good point. In a Danish book by Mogens H. Damkier I once read that Honda was the first that practised a 0,03 mm play between pistons and cylinders where manufacturers before had 0,07mm. I guess that's one of the reasons Honda engines last so long.