Yamaha XV500 project- piston ring question

[arpa]

Hi All, I drifting further and further in my recently obtained Yamaha, as it has more issues than I expected. Engine apart, replacement crankshaft and con rods on the way from Ebay, also crankshaft bearings as well.. as is usual, I started to think about replacing all parts which is accessible now, so a bunch of stuff added to the list, like cam chain, sprocket clutch and finally I thought a set of piston ring wouldn't hurt. Not because worn out, just because easy to access.
That's the point when I started to worry. Standard piston ring set is not available anymore. My research is on its way to find similar/same rings from different bikes, however, it isn't as simple as I expected. I just wondering if anyone came across with piston rings to 73mm bore, compression ring cross section is 1.2x3.3mm, the next ring is taper 1.5x3.1mm and the oil ring is 2.5x3.1mm. The next option would be to modify the piston to accommodate wider rings, especially the compression one. Anyone has done it before? Apparently I can assemble the engine with the original rings, but on the long run, I have to find some solution...

[Grumph]

If it was watercooled, I's simply tell you to go in to Cliff Bond in Ferry Rd and see what they can supply in car rings.
Probably still the cheapest option - even if the oil ring groove might have to be machined wider.

As it's an aircooled engine, I'd prefer to use rings made for that heat range.
Suzuki GSX750F or GSXR750 J come to mind. Both 73mm bore std. Pretty sure the ring widths are very close - at least the top two anyway.
Check ring groove specs in an online manual.

There will be others. Aftermarket 73mm is a popular size for things like Z1's.

[arpa]

Thanks for the quick respond, actually Cliff Bond suggested to modify the piston as the best what he can offer was wider ring. As this engine is air cooled, I guess I have to keep searching for options, I have a look those models what you suggested..

[Grumph]

Modifying ring grooves isn't a problem. I can do it if it has to be done. My experience with car rings has been a bit hit or miss.
A couple - in road motors - have worked out fine. Used in race air cooled engines, not so good. Short life expectation before oil comsumption goes up.
Usually it's loss of tension due to running them at higher temps than they were made for.

Honda ST1100 is another 73mm standard bore to look at. Although watercooled, Honda quality would be fine in an aircooled.

[husaberg]

If it was watercooled, I's simply tell you to go in to Cliff Bond in Ferry Rd and see what they can supply in car rings.
Probably still the cheapest option - even if the oil ring groove might have to be machined wider.

As it's an aircooled engine, I'd prefer to use rings made for that heat range.
Suzuki GSX750F or GSXR750 J come to mind. Both 73mm bore std. Pretty sure the ring widths are very close - at least the top two anyway.
Check ring groove specs in an online manual.

There will be others. Aftermarket 73mm is a popular size for things like Z1's.

Car rings are getting thinner by the day i was looking at some car stuff the other day Nissian micra i thin was arround that thickness.
I do have some lists and sizes but has the OP had a look for NOS on Ebay.

here is second os rings
https://picclick.com/Yamaha-Xv500-Xv...l#&gid=1&pid=1
Has he cross referenced the part numbers loked ar aftermarket pistons.

while std rings and maybe pistons are not available i bet 3mm bigger XV535 ones are
i note the conrods are the same. As are the gudgeon pins the base gasket. also the cylinder heads.
I personlly would be boring it a few mm and using the far more common XV535 parts

Late A14 Nissan top rings are 1.2

[arpa]

Thanks for all the ideas, I decided to leave it for now... for long term, I start my research about planting xv535 cylinder and piston to the xv500 engine. In theory it could work. I guess I should start a new topic.

[Grumph]

Thanks for all the ideas, I decided to leave it for now... for long term, I start my research about planting xv535 cylinder and piston to the xv500 engine. In theory it could work. I guess I should start a new topic.

If you're going to do it, grab the bits now. They were never popular, aren't economic to repair, and are being scrapped.
While the price of aluminium scrap goes up, the bits get harder to find.

[husaberg]

Thanks for all the ideas, I decided to leave it for now... for long term, I start my research about planting xv535 cylinder and piston to the xv500 engine. In theory it could work. I guess I should start a new topic.

Looking at the parts fiche it looks like the heads are the same maybe even the cylinders as the base gasket is the same i would ask on some virago sites about the conversion.
In the meantime post the measurements for the OD of the liners you have.

[FJRider]

Looking at the parts fiche it looks like the heads are the same maybe even the cylinders as the base gasket is the same i would ask on some virago sites about the conversion.
In the meantime post the measurements for the OD of the liners you have.

The XV 535 has a Bore x stroke -76 x 59 mm.

The XV 500 has a Bore x stroke - 73 x 59 mm.

[husaberg]

The XV 535 has a Bore x stroke -76 x 59 mm.

The XV 500 has a Bore x stroke - 73 x 59 mm.

Cheers did you read the whole thread FJ?

OD vs ID

[FJRider]

Cheers did you read the whole thread FJ?

OD vs ID

Sleeves can be made for any specification and pressed in. A re-bore to 535 specs may be outside the tolerances. Easier to start with the larger barrel ...

The question is ... are the pistons in it now standard size or oversize ... ??

[husaberg]

Sleeves can be made for any specification and pressed in.

Why yes, but If the two sleeves are the od is the same one doesn't need a new sleeve. Jsst bore time and cuts on the boring bar.

[FJRider]

Why yes, but If the two sleeves are the od is the same one doesn't need a new sleeve. Jsst bore time and cuts on the boring bar.

If a re-bore was the original (Factory) method of increasing the cc ... a new / good condition barrels may actually be cheaper / easier than machining the old ones. 3mm oversize required to get 535 cc ... is this a normally acceptable amount of increase in bore size for an engine of this capacity ... ???

[husaberg]

If a re-bore was the original (Factory) method of increasing the cc ... a new / good condition barrels may actually be cheaper / easier than machining the old ones. 3mm oversize required to get 535 cc ... is this a normally acceptable amount of increase in bore size for an engine of this capacity ... ???

When the Japanese make an engine they cast the cylinders around the sleeve. They do this as it gives a better heat transfer. Well back then they did.
Its cheaper to bore out the existing cylinder in most cases than it is to buy new cylinders. even second hand ones. If he gets second hand ones who is to say they wont need boring anyway.
As the base gasket is the same on both the XV500 and XV535 I hazard a guess to suggest the std sleeve will be thick enough.
When you are boring a cylinder the most of the costs are incurred in setting it up. Although the more cuts the more time of course.
3mm was common in the 70's big bore conversions its about as much as possible on most 70's singles Honda 125's etc. (wthout resleeving)

[Grumph]

You're both part correct IMO. Yamaha watercooled 4T's have pressed in sleeves. I'd pick that the casting is externally identical for both engines but they both have the same thickness sleeves...
Whic leads to the point that 3mm overbore in a 500 is probably quite feasible. They're usually quite generous with sleeve thickness but wouldn't IMO have done an extra thick sleeve for the 500 version.