Alternative 256 piston rings?

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barncat

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have been lurking for a while. great website.

i recently bought a batch of about 6 complete/parts XS's (TX's actually) in various states of non-running repair. mostly '73's with a couple '72's- all 256 motors i believe, some of them stuck from sitting as usual. beginning to tear into them for rebuilds and lo and behold piston rings for the old motors, particularly oversize, are pricey and scarce...

has anyone found common automotive rings yet for the stock 256 pistons? they are 75mm x 1.5, 1.5, 2.8, from top to bottom apparently.
 
Welcome to the forum, barncat. You seem to be fairly well educated on these rings. Here's a thread about the XS rings that covers some automotive options:

http://www.xs650.com/forum/showthread.php?t=133

However, in the last couple of years, a new eBay vendor has appeared, Cruzinimage_co, that offers piston and ring sets that are quite economical, and sell rapidly. Here's his two ringsets for the '256' engines:


Item: 70-73 YAMAHA XS1 STANDARD PISTON RING SET Two Piston Rings are included CI-XS1PR

URL: http://pages.ebay.com/motors/link/?nav=item.view&id=161344396432&alt=web

Alt URL: http://www.ebay.com/itm/70-73-YAMAH...-Piston-Rings-included-CI-XS1PR-/161344396432


Item: 70-73 YAMAHA XS1 0.5mm OVERSIZE PISTON RING SET Two Piston Rings are included

URL: http://pages.ebay.com/motors/link/?nav=item.view&id=141055017276&alt=web

Alt URL: http://www.ebay.com/itm/70-73-YAMAH...G-SET-Two-Piston-Rings-included-/141055017276
 
thanks for quick assist TooMany. i knew of Cruzinimage but not that specific offering. only minor drawback is shipping time from across the globe...

he knows more English than i know Japanese- but i assume that ad is for (2) sets of rings for (2) pistons for 25 bucks? that's a deal.

first motor apart and cylinders are in great shape despite one obstinate piston removal, and bores are stock. just going with light hone to break glaze. have a bad exhaust valve and guide to re-do also.

since i don't have the new rings in hand, i'm guessing that 2nd oversize rings can be filed to nice fresh minimum spec to go back into "stock" bores? (oil ring expanders to be re-used). the curvature of oversize rings for a given nominal bore probably does not change perceptibly?
 
that should have been "Two" not "Too" in your handle above, sorry... just caught that.

ideally what i'd order is 1st over just to be safe with a bit of honing. i suppose i could hope the stock rings will have enough material to gap properly, but i was going to order several sets. will skip the 2nd over idea on your advice. thanks.
 
barncat said:
... just caught that...
Click to expand...

Haha, gotcha!

I don't see a problem using stock size rings on stock bores, unless the cylinder(s) fail the bore measurements tests. Worst case, bore wore 0.002" over stock (which is the limit), translates to an additional 0.006" ring gap. The rings should have enuff material to accomodate that...
 
i'm sold on ordering from Cruzin' based on what i've read, and great prices. good to know they ship fast too.

have a Brown & Sharpe telescoping gage on order to accurately check bores. will probably have to order a stock ring set to see whether they stay in spec for used/honed cylinders. i want to set everything to minimum gaps...

being new to 650's, was somewhat disappointed to discover after the fact that 256 motors are not as easy to mod as 447's, but i did get a good deal on 3 trailer loads of stuff.
 
update: excellent ordering experience with Cruzinimage! 2 sets (enough for 4 pistons) of 256 stock rings for about 60 bucks in my mailbox from Japan in like 5 days. ya can't beat that. he (Mitsuo) even refunded half the doubled Ebay shipping with out my asking.

pleased to report that with nice fresh hone/deglaze the rings still gap out at .014" in stock bores, well with in spec.

btw, the 2nd ring has a ledge and is not stamped with a marking- does the ledge go up or down? i believe the latter but have not done this recently and it's not in the Clymer manual...
 
Hi all, I purchased a "YAMAHA XS650 0.5mm OVERSIZE PISTONS SET 447 TYPE" from Cruzinimage and the ring slots are 1.5, 1.5, 2.8. So it looks like if I or someone further down the line wanted to change the rings in the bike, they would have to purchase 256 or XS1 rings? I presume the XS1 and 256 compression and scraper rings are the same size and the later models (447 and 533) have a smaller compression rings right 1.2, 1.5, 2.8?

So I have a 447 type 256 ring set piston? :thumbsdown:
 
Last edited:
Its definitely a 447 piston, 20mm wrist-pin, 80mm height, top edge of piston to wrist-pin center around 40mm ish, it was from Cruzinimage and has the thin clips that nobody likes, have a look
IMG_0828.JPG
 

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