availability of std rings

[RDDave]

My 4,000 mile '75 350 has 95lb compression. It runs starts and runs good but will occasionally foul a plug during warm up. Once warmed up, it has never fouled one. I have the heads off and it is still stock bore and the cylinders look okay. There were no rattles or noise inside when running so I don't think the piston top cylinder gap is excessive. I will pull the cylinders tomorrow for a more in depth look and measurements, but right now I am thinking of knocking the glaze off the cylinders and installing new rings. I have spare cylinders and heads that I may send off to be modded  but for now a re-ring job may be the ticket.

Who has std bore rings that will fit the Yamaha pistons. Yamaha apparently doesn't.

Thanks again for the advise! I don't know what I would do without it. 

[m in sc]

if you have std rings (not dykes or 'l' shaped)  here you go:  https://yambits.co.uk/rd350-piston-ring-kit-std-p-8353.html

[RDDave]

Again, thank you. I will pull the cylinders tomorrow and determine the style of rings.

 

[dgorms]

I might have some stds. in my stash. Let me know what style.

[RDDave]

Well, well, well; Pulled the cylinders today. Things looked great. Piston to cylinder was good, no scratches in the cylinders, nor were there any scuffs on the pistons. The rings were the only thing out of spec at .022. It is still standard bore. Everything cleaned up good and was just wanting to bust the cylinder glaze and put in new rings. BUT! They are Dykes. Looks like there aren't any out there. Unless someone knows of some. I have filed down 1st oversize rings to std bores many times on 4 strokes, but I don't know about doing that with these, so I am not looking for 1st over.

Ebay has Chinese Kveldwulf piston kits for $45 which they say are standard. Anybody know if they are any good?

Any other suggestions? Please..............

[m in sc]

IF i were in your position and going to swap JUST pistons, I'd buy the yambits std pistons. I run them in my tzr250. (1st over in mine) https://yambits.co.uk/rd350-piston-kit-std-p-8146.html


me? id just freshen it up to a .25 over bore to make sure its all square and nice.

[RDDave]

Following your advise, I just ordered the .50 over simply because they were cheaper along with a couple of other items.

 

[SoCal250]

Std bore dykes rings are out there, they're just a little on the expensive side.
Yam part # 360-11610-02
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m570.l1312&_nkw=yamaha+360-11610-02&_sacat=0
https://www.cmsnl.com/products/piston-ring-set-std_3601161002/

If the pistons and bores are still good you would come out ahead just buying 2 sets of OE std dykes rings instead of paying for 2 new piston kits and 2 holes bored, and you would preserve two oversizes in your cylinders. Also when buying any vintage OE rings I would ask the seller to confirm the ring style to ensure they are "L" (dykes) type because I've seen many mislabeled on eBay.

[RDDave]

You make some good points and being that my cylinders measured good, I would have preferred to just go with new rings. BUT, these lasted 49 years and 4,000 miles. And although it was time to change, they weren't junk and I could have ran them longer.

I will never put another 4,000 miles on the bike. I just don't ride that much any more. And there are a ton more oversizes available. So, this is the most practical way to go. Unless I foul something up, this will last a lot of years. Who knows, maybe another 49. 

[dgorms]

I didn't see any std 350 rings in my stash, however I will be posting a list of what I do have soon. There is at least 20 sets in my box.

[Jspooner]

20 sets!! Good God!! LOL

[m in sc]

fwiw you can file dykes rings 'down to size' have done it years ago. 

[RDDave]

Many years ago, I did a lot of work on 3 wheelers. In particular the Hondas. The Big Reds back then were very prone to burning oil and lots of guys wanted their 185cc rides kitted up to 205cc. I did dozens and dozens. Some guys wanted Honda parts rather than Helm or whoever. But the Honda rings came out of the box out of spec. The end gaps were HUGE. And that was the problem with the Big Reds burning oil. For the guys that wanted Honda parts, I would get the next size rings and file them to spec. Given Honda's reputation for quality, I never understood that.

But I had never tried filing Dykes. Never really had the need. If I could have found .25 O/S Dykes for my 350, with your input, I may have tried it. But..................

[busa1300]

Does this bike still have its original crank seals?

[RDDave]

I cannot know for sure, but I would think so.