XS360 Piston Rings... cross compatibility?

Norman1950

Norman1950

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In doing some research it seems almost impossible to find STD rings for the xs360. But in the searching I came across 1972-76 KZ900 piston rings. The pistons are also a 66mm. So I downloaded the KZ service manual to compare with the xs360 manual. The numbers are pretty much the same. I believe that the xs360 manual has an error on the cylinder bore. As 66mm is not 2.5900" as it is 2.5984".

But with that here are copies of the 2 sheets. Anyone see a reason why the KZ rings won't fit the XS? Plus the KZ's are heck of a lot cheaper and easy to find.

Thanks for the help and input.

XS360 Manual



KZ900 Manual

 
If the 66mm will work that would be good. But I would worry about thickness and the other rings ( oil control ect.) Try ebay or even some yamaha dealers to see what they have. As long as the thickness is correct the diameters ( if too long) they can be filed down to fit.
 
In some more reading of the KZ900 manual I see they kindly gave the ring thickness. I will have to go home tonight and measure and see what I come up with.

 
In looking more into this, looks like the KZ900 only has a wavy oil ring, doesn't have the 2 rings on each side (ebay picture was generic, DAMN THEM).

The stock xs360 top ring is 1.41mm thick and the 2nd ring is 1.50mm thick. Close but not worth trying out in my mind.

Guess it is on to the .25 over rings and file them down to fit.

Thanks for the input
 
I know Norman has moved on from this issue and gone to oversized pistons but I wanted to resurrect it because I came across another option.

Some Lambretta Scooters have 66mm bores and there are 1.5mm thick rings available.
http://www.ebay.ca/itm/LAMBRETTA-200-CC-PISTON-RINGS-66-00-MM-X-1-5-RINGS-/251865572130?pt=LH_DefaultDomain_0&hash=item3aa45ba322

Norman's measurements came to 1.41mm and 1.5mm thick for stock 360 rings. I don't have a caliper that precise but comparing the thickness of top and bottom rings by sliding my finger between the two side-by-side I can't feel any difference (works for .11mm thick paper). They also both fit as easily into either slot in the piston.
I'm thinking 1.5mm rings for both top and bottom wouldn't be an issue.

The Lambretta 200's stock end-gap specs are a pretty close match for the 360's at .2mm-.35mm vs the 360's .15mm-.35mm, though the end-gap style is different.

The only information I haven't found is the ring width/inner diameter.

For the price it's awfully tempting to try a set. Thought I'd check opinions on here before going ahead with it.

What's the worst that could happen? Risk of damaging the cylinder wall? Precautions?
 
I appreciate the suggestion. It's not bad price-wise, but it's the only one on eBay and I'd need two. There are matched sets available from Germany but they are 99euros. A bit prohibitive.

The idea is to find a readily available alternative.
The fourth-oversize ring for Honda ATC 200s is also 66mm but I haven't been able to find info on the thickness.
There are also wiseco 66mm rings but they're almost all .8mm thick and Wiseco means more $$$.
Did find some 66x1.5mm rings for chainsaws but somehow that seems like a bad idea.

I have alerts in my eBay app that notify me whenever certain xs360 parts come up for sale. :)
 

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