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Need Help With Piston ID
- Thread starter gene xs
- Start date
Using the depth gage on my verniers, so it's hard to get a good accurate depth on the curved surface. Actual measurement might be slightly more.
Top gland is 3.7 mm deep
middle gland is 3.5 mm deep (seems slightly shallower than the top).
The true depth appears to be ~3.7 mm on both. The 3.6 mm thick rings can both be pushed in to the same depth - slightly below the surface of the piston.
Oil gland groove is wavy with minimum depth of 2.0 mm
Looks to be slightly more than 2.0. The 2.5 mm wide oil ring stays proud of the surface by about 0.5 mm
piston diameter 79.95 mm (again with the verniers).
So, any idea what I have?
Thanks!
Top gland is 3.7 mm deep
middle gland is 3.5 mm deep (seems slightly shallower than the top).
The true depth appears to be ~3.7 mm on both. The 3.6 mm thick rings can both be pushed in to the same depth - slightly below the surface of the piston.
Oil gland groove is wavy with minimum depth of 2.0 mm
Looks to be slightly more than 2.0. The 2.5 mm wide oil ring stays proud of the surface by about 0.5 mm
piston diameter 79.95 mm (again with the verniers).
So, any idea what I have?
Thanks!
Offhand, no. The casting roughness on your piston, around the recessed sides, convinces me that it is indeed an aftermarket piston offering. I seem to recall some early Wisecos looking like that. They still have ringsets for their 80mm pistons, but not for the 256 80mm pistons.
It's just that we're in the same boat with these non-existant '70s rings.
Yours being a 477-type piston affords you more options. Could just get new 447 80mm pistons and rings, and you'll be up-to-speed with the newer ring geometries.
MikesXS has rings for the 80mm pistons, but the top ring will be 1.2mm, and the widths for the 2nd and oil are unknown.
Those Toyota rings look promising, but they're 81mm. A bit much.
We need more ring geometries. Like for the TX750, Alfa 1750. I have a set of 80mm (Moto-Guzzi, I think) rings buried somewhere. Need to get their geometries as well. There may be others. I also need to catch-up on ring backspacing criteria.
I'm fully expecting that some type of mix/match will have to be cooked up.
Your description of your oil ring setting depth is odd, makes me wonder if some previous ring/piston match game has occurred.
Sticking these in here for future reference. From Grumpy's Performance:
http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/
This shows 0.005" as minimum ring/groove radial back clearance, but I've found other references that call out values from 0.010" to 0.015" as minimums.
http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/
This shows 0.005" as minimum ring/groove radial back clearance, but I've found other references that call out values from 0.010" to 0.015" as minimums.
Thanks for all your help.
It's very odd, the piston has "Yamaha"and "80" cast inside, which leads me to believe that it isn't aftermarket but. However, the high dome does not look like any of the TX500 pistons I've seen (the best bet for a contemporeaneous Yamaha substitute).
If rings are not readily available, my best bet appears to be to just reassemble the engine with new gaskets and valve seals (leaking seals were the original reason for me to tear the engine down), and see how she runs. If it's not smoking and is running strong, then I am good. If the bottom end needs a rebuild, I would be inclined to get used stock bore jugs and rebuild them or I could go one over 80 mm.
This was purchased as a project bike after all
.
It's very odd, the piston has "Yamaha"and "80" cast inside, which leads me to believe that it isn't aftermarket but. However, the high dome does not look like any of the TX500 pistons I've seen (the best bet for a contemporeaneous Yamaha substitute).
If rings are not readily available, my best bet appears to be to just reassemble the engine with new gaskets and valve seals (leaking seals were the original reason for me to tear the engine down), and see how she runs. If it's not smoking and is running strong, then I am good. If the bottom end needs a rebuild, I would be inclined to get used stock bore jugs and rebuild them or I could go one over 80 mm.
This was purchased as a project bike after all
.
There's a pair of old style rings here. Could ask these guys about the ring dimensions.
Item: NOS K&L Piston Rings XS650 Big Bore Kit 650 To 750 Std Standard Yamaha
URL: http://pages.ebay.com/motors/link/?nav=item.view&id=351338521118&alt=web
Alt URL: http://www.ebay.com/itm/NOS-K-L-Pis...Kit-650-750-Std-Standard-Yamaha-/351338521118
Item: NOS K&L Piston Rings XS650 Big Bore Kit 650 To 750 Std Standard Yamaha
URL: http://pages.ebay.com/motors/link/?nav=item.view&id=351338521118&alt=web
Alt URL: http://www.ebay.com/itm/NOS-K-L-Pis...Kit-650-750-Std-Standard-Yamaha-/351338521118
TwoMany, when you've been looking into rings of other makes and vehicles did you look into BMW at all? I don't know where you got information for the other rings such as Toyota, the BMW M20B20 2 Litre engine has 80mm bore, 3.149" and I can't find any spec data on them... looking though.
I have a set of rings here for the M20B25 2.5 Litre 84mm bore and the dimensions of the rings look kinda promising so I'm wondering if the M20B20 ring set might be worth looking at. Did you check those out in your researching?
Just found this website... might be worth a look if you didn't find it already.
http://www.summitracing.com/int/sea...4294882323&SortBy=Default&SortOrder=Ascending
EDIT: not much help am I... found this for BMW M20B20 80mm bore...
PISTON
GL 71.70
KH 43.40
GL-Length; KH-Compression Height;
RINGS
Top 1.50
2nd 2.00
O i l 3.50
PIN
Diameter 22
Length 61
I have a set of rings here for the M20B25 2.5 Litre 84mm bore and the dimensions of the rings look kinda promising so I'm wondering if the M20B20 ring set might be worth looking at. Did you check those out in your researching?
Just found this website... might be worth a look if you didn't find it already.
http://www.summitracing.com/int/sea...4294882323&SortBy=Default&SortOrder=Ascending
EDIT: not much help am I... found this for BMW M20B20 80mm bore...
PISTON
GL 71.70
KH 43.40
GL-Length; KH-Compression Height;
RINGS
Top 1.50
2nd 2.00
O i l 3.50
PIN
Diameter 22
Length 61
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TLCbobber, thanx for the help. Looking up the BMW offerings, like that M20 (also 320, 323, 520, M60) in 80mm shows only the top ring is the correct thickness, but it is a torsional style (inside edge chamfer) and not a barrel style. Not sure how that would work here.
Thanx for the Summit Racing rings lookup. Using that link, narrowing down to a useable bore diameter of 81mm, produces these ringsets:
http://www.summitracing.com/parts/slp-e-456kc/overview/
http://www.summitracing.com/parts/slp-e-456x/overview/
Which is the same 83-89 Toyota Corolla 1.6L 81mm ringset I posted earlier (post #15).
Not a bad price for 4 sets of rings.
I'm chasing some other 80mm ring offerings used on 99-02 Mazda and 83-94 Mitsubishi, looking at using their top rings, then match with other oil rings, like 88-99 Hondas and 99-02 Mitsubishi.
Yeah. It's a mess...
Thanx for the Summit Racing rings lookup. Using that link, narrowing down to a useable bore diameter of 81mm, produces these ringsets:
http://www.summitracing.com/parts/slp-e-456kc/overview/
http://www.summitracing.com/parts/slp-e-456x/overview/
Which is the same 83-89 Toyota Corolla 1.6L 81mm ringset I posted earlier (post #15).
Not a bad price for 4 sets of rings.
I'm chasing some other 80mm ring offerings used on 99-02 Mazda and 83-94 Mitsubishi, looking at using their top rings, then match with other oil rings, like 88-99 Hondas and 99-02 Mitsubishi.
Yeah. It's a mess...
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Wasn't much help though, I just seem to be filling the thread with irrelevances.
I have to ask, though, how does an 81mm ring work for an 80mm piston? Isn't it too big?
I realise this may put you into the price realm of new pistons, but what about having the ones you have machined to accept the rings of your choosing? I'm still curious about a tx750 set, just went to tx750 forum.... bit of a ghost town.
I have to ask, though, how does an 81mm ring work for an 80mm piston? Isn't it too big?
I realise this may put you into the price realm of new pistons, but what about having the ones you have machined to accept the rings of your choosing? I'm still curious about a tx750 set, just went to tx750 forum.... bit of a ghost town.
tx750 STD ring set part# 341-11610-01-00
https://www.yamahapartsandaccessori.../star-mcy#/Yamaha/TX750_-_1973/CRANK_-_PISTON
Looking on the parts fiche the xs1b has 2 sets of pistons listed as follows:
https://www.yamahapartsandaccessori...s/star-mcy#/Yamaha/XS1B_-_1971/CRANK_-_PISTON
256-11631-02-96 PISTON STD | PN315
256-11635-02-00 PISTON 1 O/S 0.25 (0.25MM 1ST O | ALTERNATE PARTS
256-11636-02-00 PISTON 2 O/S 0.50 (0.50MM 2ND O | ALTERNATE PARTS
the above I'm taking to be for 650 motors.
reference the next part# which is also for xs1b on the fiche I'm guessing it's for larger cyclinders since numbers ring true with tx750 part#shown at the top.
256-11610-00-00 PISTON RINGSET STD (STD)
256-11610-10-00 PISTON RINGSET 1ST (1ST O.S.) | ALTERNATE PARTS
256-11610-20-00 PISTON RINGSET 2ND (2ND O.S.) | ALTERNATE PARTS
11610 is the main part# so if you can get tx750 rings I reckon you're good to go.
http://www.ebay.co.uk/itm/Nos-Oem-P...-Head-73-74-/261836827331?hash=item3cf6b0eac3
https://www.yamahapartsandaccessori.../star-mcy#/Yamaha/TX750_-_1973/CRANK_-_PISTON
Looking on the parts fiche the xs1b has 2 sets of pistons listed as follows:
https://www.yamahapartsandaccessori...s/star-mcy#/Yamaha/XS1B_-_1971/CRANK_-_PISTON
256-11631-02-96 PISTON STD | PN315
256-11635-02-00 PISTON 1 O/S 0.25 (0.25MM 1ST O | ALTERNATE PARTS
256-11636-02-00 PISTON 2 O/S 0.50 (0.50MM 2ND O | ALTERNATE PARTS
the above I'm taking to be for 650 motors.
reference the next part# which is also for xs1b on the fiche I'm guessing it's for larger cyclinders since numbers ring true with tx750 part#shown at the top.
256-11610-00-00 PISTON RINGSET STD (STD)
256-11610-10-00 PISTON RINGSET 1ST (1ST O.S.) | ALTERNATE PARTS
256-11610-20-00 PISTON RINGSET 2ND (2ND O.S.) | ALTERNATE PARTS
11610 is the main part# so if you can get tx750 rings I reckon you're good to go.
http://www.ebay.co.uk/itm/Nos-Oem-P...-Head-73-74-/261836827331?hash=item3cf6b0eac3
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Yes, It's too big. Just a desperation move.
I have a set of chuckjaws that I machined long ago for holding those old 80mm pistons. I could widen the ring grooves, but that's going the wrong way. The grooves need to be narrower for the modern rings.
TX750 rings are offered by that CruzinImage eBayer, occasionally in the 2nd over size. I just don't have the ring dimensions. Might be that the only way to get the dims is to order a set...
You don't need ring dimensions since part#11610 is listed as piston rings for both xs1B and TX750.
If the ring dimensions were wrong they wouldn't have same part number 11610 and I really doubt Yamaha would make 2 different size sets for 2 twin 750s with 80mm pistons within 2 years of each other. The pistons are very different but the rings must be the same. That last link I provided is a seller with 3 standard sets for sale.
If the ring dimensions were wrong they wouldn't have same part number 11610 and I really doubt Yamaha would make 2 different size sets for 2 twin 750s with 80mm pistons within 2 years of each other. The pistons are very different but the rings must be the same. That last link I provided is a seller with 3 standard sets for sale.
That #11610 is a code number for piston rings. ALL Yamaha piston rings will have that code.
The distinctions are found in the first 3-digit code (bike model), and the suffixes (part revisions)
As an example, here's where the ring design changed with the TX650A.
Thinner top, different 2nd.
View attachment 50405
My head's spinning. Been downloading and scanning ring catalogs all night. Seems that 80mm offerings are posing a challenge. Taking a break for now...
Thinner top, different 2nd.
View attachment 50405
My head's spinning. Been downloading and scanning ring catalogs all night. Seems that 80mm offerings are posing a challenge. Taking a break for now...
jonesey
Dyed in the wool 650 nut
G/day, Too Many, TLCbobber,GeneXS
I just stumbled across this thread which is 4months old, I have some TX750 parts at home and I can measure the piston rings tonight, after work. I also have some 80mm Alfa Romeo pistons and rings and can measure as well.
Interestingly the Alfa pistons are made by "Mondial". I hope the rings have part numbers.
I know it's been a while and you've probably resolved the issue but just for future interest I can take the sizes
I just stumbled across this thread which is 4months old, I have some TX750 parts at home and I can measure the piston rings tonight, after work. I also have some 80mm Alfa Romeo pistons and rings and can measure as well.
Interestingly the Alfa pistons are made by "Mondial". I hope the rings have part numbers.
I know it's been a while and you've probably resolved the issue but just for future interest I can take the sizes
Thanks for your help, Jonesy. We never were able to identify a complete ring set. You might be able to.
I took the XS back to stock bore - new used cylinders and NOS pistons, new rings. So I am back on the road. Still have the 750 jus and slugs.
Thanks!
I took the XS back to stock bore - new used cylinders and NOS pistons, new rings. So I am back on the road. Still have the 750 jus and slugs.
Thanks!
Jonesey! That would be great!
I was able to dive deep into one of my parts boxes from long ago, and retrieved an original Rocky Cycle relabled XS650/750-80mm ringset box for the 256 type engine. Didn't notice it back then, but the edge of the box has a TX750 part number, the earlier -00 TX750 ringset number.
It seems that there were 2 series of TX750 ringsets, and I have no info on the differences there.
jonesey
Dyed in the wool 650 nut
G/Day Gents.
This is what I found, measured with the finest Chinese Vernier known to mankind so +- 0.10 mm i'm afraid.
TX750 Rings, Thickness, Width, Piston Groove Depth.
Top Ring 1.5 mm 3.6 mm 3.75 mm
Middle Ring 1.5 mm 3.6 mm 3.8 mm
Oil Ring (3 piece ) 2.8 mm 3.6 mm 3.65 mm
Alfa Romeo 80 mm, 22mm Small end pin dia. Piston & rings
Top Rings 1.5 mm 3.3 mm 4.0 mm
Middle Rings 1.7 mm 3.6 mm 4.0 mm
Oil Rings (3 piece) 3.8 mm 4.0 mm 4.0 mm
3.5 mm (piston)
You will notice the oil groove still has to be opened up to accept the oil ring, Alfa said that is the only size available now. No part numbers on the piston rings i'm afraid. Pistons 66.41.4.9197.
Many many years ago Don Vesco was selling 80 mm pistons for the XS 650 with TX piston rings but the oil ring tells me its not one of those either.
Some time ago I gave a Guy in Durban a good pair of TX pistons for a Laverda750 SF a direct fit apparently, be interesting to know what the Laverda rings are like?
Also on the TX750 forum a German Guy rebuilt a TX using Fiat 126 pistons Part No. 92050610, the pistons of course are flat topped and no good to us but the rings are another posibility?
Another guy in Johannesburg (not John) rebuilt an XS2 with Opel cub Piston rings but the 75 mm version maybe Opel (GM) have 80mm versions as well.
Too Many, I have no idea what changes the TX piston rings underwent in its poor short life, I have a parts manual and about 4 sets of pistons so I will look if I can see a change. Everything was bought as the dreded box of bits so no way of telling early from late but I'll still look. A real shame because set up properly the TX was a really smooth engine, as smooth as a Honda 4 dare I say. Cheers for now.
This is what I found, measured with the finest Chinese Vernier known to mankind so +- 0.10 mm i'm afraid.
TX750 Rings, Thickness, Width, Piston Groove Depth.
Top Ring 1.5 mm 3.6 mm 3.75 mm
Middle Ring 1.5 mm 3.6 mm 3.8 mm
Oil Ring (3 piece ) 2.8 mm 3.6 mm 3.65 mm
Alfa Romeo 80 mm, 22mm Small end pin dia. Piston & rings
Top Rings 1.5 mm 3.3 mm 4.0 mm
Middle Rings 1.7 mm 3.6 mm 4.0 mm
Oil Rings (3 piece) 3.8 mm 4.0 mm 4.0 mm
3.5 mm (piston)
You will notice the oil groove still has to be opened up to accept the oil ring, Alfa said that is the only size available now. No part numbers on the piston rings i'm afraid. Pistons 66.41.4.9197.
Many many years ago Don Vesco was selling 80 mm pistons for the XS 650 with TX piston rings but the oil ring tells me its not one of those either.
Some time ago I gave a Guy in Durban a good pair of TX pistons for a Laverda750 SF a direct fit apparently, be interesting to know what the Laverda rings are like?
Also on the TX750 forum a German Guy rebuilt a TX using Fiat 126 pistons Part No. 92050610, the pistons of course are flat topped and no good to us but the rings are another posibility?
Another guy in Johannesburg (not John) rebuilt an XS2 with Opel cub Piston rings but the 75 mm version maybe Opel (GM) have 80mm versions as well.
Too Many, I have no idea what changes the TX piston rings underwent in its poor short life, I have a parts manual and about 4 sets of pistons so I will look if I can see a change. Everything was bought as the dreded box of bits so no way of telling early from late but I'll still look. A real shame because set up properly the TX was a really smooth engine, as smooth as a Honda 4 dare I say. Cheers for now.
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