another rings question for +.080

[mikeb]

I’ve got +080 JP pistons and JP rings and burn some oil when active with the wrist. I know JP rings have a reputation. But finding good +080 rings is a bit tricky. I assume the JPs are made to the AE/hepolite specs (their B33 ones are). If so, maybe a hone and:

1. would rings for a T120/TR6 (71mm) +040 fit? The diameter and heights would be right but I can’t find good info on the ring depth. I’ve read some t120 pistons have an oil ring groove depth of 3.70mm and others 2.80mm. I think I’ve read here that some people fit them…. Thoughts on this? Sidenote would be that if t120 rings do fit a10 pistons then anyone with +40 a10 pistons could have more choices as below.

2. are there other suitable brit bikes/matches to get rings at 72mm, with 2x 1/16, 1x 1/8 (oil) and the right depth?

Regarding quality rings:
IMD appear to have a 3-piece oil rings at +040 for the A10 but not sure about T120 (I’ve emailed to ask). Will report back if it’s a ‘yes’.

Or has anyone used these:

3. Deves do a gapless ring set for a t120/tr6. They get some good press on triumphrat. http://www.deves.com/devesrings/cycles_TRIUMPH.php BTW they also do standard a10 sizes. Anyone tried these?

4. Goetze rings also get some good press and are easy to source. As far as I can tell they’ve got a 1 piece oil ring. Anyone tried these?

5. I think US based ‘Total Seal’ make a 3 piece oil ring for the t120 - C8396
http://webcatalog.totalseal.com/Home/partdetail/1236 – anyone tried these?

6. Hastings 2C6938-40 for the t120 have a one-piece cast oil ring and non-chrome top ring. Any views for an a10?

Thanks
Mike

[Swarfcut]

Mike.

 From my 1989 AE/Hepolite catalogue, the Hepolite Triumph Pistons (code 17844) for 70.988mm/2.7948" bore use Hepolite ring set R11050.

 Dimensions for this set are Compression Rings  0.0625"/1.588mm  thick.

                                               Oil Rings          0.1250"/3.175mm  thick.

 The groove depth (how far the piston groove lies into the piston face) is given as 0.100"/2.54mm for all rings and grooves.

 Sorry to be simplistic but there is a chance of confusing ring depth with ring thickness.

 On these dimensions the grooves are 1/16" and 1/8" wide, identical to the BSA. My catalogue does not list A10 pistons, (it's too modern) and regrettably the groove depth from the horse's mouth is not to hand. Measuring an old piston has a groove depth of 1/8" (0.125"/3.175mm) for compression and oil grooves. Piston casting here is Hepolite 11016. By this comparison the Triumph rings require a slightly less deep ring groove, and as such should fit the BSA Piston.

 Disclaimer. That's my take, but as usual I do not claim 100% accuracy, just giving a suggestion on information to hand.

 Cheers.

 Swarfy.

[mikeb]

Thanks Swarfy for your measurements!

i measured an a10 NOS AE/hepolite +.060 piston to have an oil ring groove depth of 3.14mm (about 1/8") and the comp ring groove depth at  3.3mm (= probably 1/8") - these being depth (into the piston) not height. whereas the rings themselves measured as 2.53mm (oil) and 2.95mm (comp) deep. i tried, but don't claim high accuracy on this.

I am gong to assume the depth is the same as the triumph. the strange thing is this site:
http://www.deves.com/devesrings/cycles_TRIUMPH.php
suggests the t120 pistons have 2 different Oil ring groove depth - 3.70mm and 2.80mm (not heights).

I might be overthinking this again 

but it would be good to hear any reports on the Deves, Goetze or total seal rings if there are any

cheers

[Shark]

I have used Goetze rings on the last two jobs, both Triumphs, and so far so good.

[BSA_54A10]

Whatever you do, do not fit the JP rings.
They are too hard and will take 1000 km ( or more ) to bed in properly .

[mikeb]

Trevor - yes I'm trying to avoid those as already have them installed and oil-burning, tho interestingly srm replied to suggest I fit JP rings to JP pistons  i won't be doing that.

also found draganfly listing the a10 rings as:
comp 2x 1/16, depth = 0.120"
oil 1 x 1/8, depth = 0.105"
https://www.draganfly.co.uk/data/pdf/piston.pdf
gotta appreciate draganfly some days for all the info they freely put online.   

this pretty much matches my measurements.

I'm trying to get some made locally tho failing that will likely go Goetze

cheers

[TimK]

Hi Mike
I fitted JP pistons and rings after a rebore to +60 and gave them a couple of hundred miles to bed in, but after that the exhausts were still smoking hard and I had an constant drip of oil from the breather. After getting a bit of advice on this forum I got hold of some Gandini rings and it was an immediate transformation - no smoking and a (almost) dry breather.
Cheers
Tim