Author Topic: piston ring thoughts  (Read 289 times)

Online berger

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piston ring thoughts
« on: 09.09. 2020 19:51 »
hello you lovely lot, I have a question about un marked piston rings. I have seen some STD size rings for sale at a well known suppliers and I mailed them to ask what make they were. the answer was -- they don't know. well that is a really good answer from a place that loads of you have used and I used once only to have to send the crap back they sent me. so I ask the question -- are they marked TOP for fitting. the answer was no markings. have any of you had experience with this kind of thing or have fitted an un known make of rings without markings for fitment and they have been useable. I despair and become more convinced that many suppliers just want OUR money and have no interest in anything else!!

Offline Swarfcut

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Re: piston ring thoughts
« Reply #1 on: 09.09. 2020 20:47 »
bergs. Piston rings come as the familiar compression rings and oil control rings. The compression rings have variations and can come with different  profiles depending on application.

 The A10 ring grooves are imperial measurement, first and second grooves are the same, 1/16", the oil ring groove is wider.  If the profile of the ring is not symmetrical, it will be marked "Top". Typically tapered profile or "ridge dodger" type where the top ring is designed to avoid the wear ridge at the top of the bore. The second ring sometimes comes with a " Napier Scraper" profile. The scraper looks like a hook in profile, and this is fitted on the underside. What's in the pack depends on the ring set you chose.

 With no markings you can assume the profile is symmetrical and they can be fitted either way up. The ring should look the same from top or bottom.   Measuring the ring for correct bore fitment is awkward to do, just putting it squarely in the bore and measuring the gap is a reasonable way to estimate if they will do. Oil rings are solid cast iron or spring loaded scraper rail type, again, depends on the set.

 Unmarked, no box means they have to be cheap and the supplier needs to have a proven good customer service record.

 Back in the day Hepolite set ref 3650 (A10 70mm bore) originally contained two identical plain compression rings.  These can be fitted either way up, but being plain (in other words a symmetrical profile), are only suitable for a newly bored cylinder or a used cylinder where the wear ridge at the top has been removed....otherwise the new top ring will hit the ridge. Later sets may differ in ring profile, I don't have my catalogue to hand to check.

 Hepolite (the old original AE Company) suggest a ring gap of 3 thou per inch of bore diameter. This applies to the compression rings and the cast iron oil control ring. This ring can be fitted either way up.

 Swarfy

Online berger

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Re: piston ring thoughts
« Reply #2 on: 09.09. 2020 21:33 »
cheers swarfy.. its just that all my life  [ except for one disaster ] I have only come into contact with rings that were marked,  even if it was a stamped dot on the 2 top rings. I am a bit nervy because ANOTHER well known supplier sent me un marked rings that were only any good for the scrap bin and I had to strip the engine and fit a named and marked set of rings.

Online berger

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Re: piston ring thoughts
« Reply #3 on: 10.09. 2020 00:10 »
well panic over , I have found some gpm/ gandinis  STD size that are a trifle expensive but must be better than some non descript plastic bag packed head ache tackle that never should be on a shelf and for sale in the first place. rant over *rant*

Offline Joolstacho

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Re: piston ring thoughts
« Reply #4 on: 10.09. 2020 01:01 »
Talking of pistons / rings, does anyone have any experience of 'Forseti' brand?

Online muskrat

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Re: piston ring thoughts
« Reply #5 on: 10.09. 2020 01:37 »
G'day Jools.
Forseti are a cheap made in China brand. I put pistons, rings, cam chains and gaskets in the Rhonda about 5000 miles ago. Not blowing smoke yet but I can hear the chains flopping about. I won't be going back.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Online metalflake11

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Re: piston ring thoughts
« Reply #6 on: 10.09. 2020 02:37 »
well panic over , I have found some gpm/ gandinis  STD size that are a trifle expensive but must be better than some non descript plastic bag packed head ache tackle that never should be on a shelf and for sale in the first place. rant over *rant*

You won't go far wrong with Gandinis, S.R.M. fit them in all their A10 builds (maybe others??) and it's all I've ran for thirty odd years with great success.

Maybe worth a call to them to get the relevant clearance and gap measurements?
England N.W
1960 A10
England

Offline Joolstacho

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Re: piston ring thoughts
« Reply #7 on: 10.09. 2020 02:45 »
Thanks boys... but I'm a bloody imposter!!!
It's actually not for my BSA, it's for a (hush mah mouth) Yamaha TY175 Trials bike.
The Forseti is less than half the price of a Wossner etc. It's not a high-stress application, no sustained high revs.

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Re: piston ring thoughts
« Reply #8 on: 10.09. 2020 12:44 »
metalflake11 I discovered gandinis some years ago in a local shop after srm had sent me non descript rings that threw oil out and were studied by marking blue contact firstly by me then in the bike shop and an engineering shop. we decided they would never bed in. the gandinis were gapped perfectly and worked straight away. the irony is these gandinis are coming from srm. I often wonder why they sent me the crap ones because after I had a phone call with them they told me they had gandinis on the shelf, by that time I had sent the crap ones back and funnily enough the gandinis I bought were cheaper than the bag of crap. another case of THEY want our money. as always in this age.

Offline Slymo

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Re: piston ring thoughts
« Reply #9 on: 11.09. 2020 23:14 »
One more big tick for Gandhi rings. Fitted them to my Super Rocket and it now burns almost no oil and the oil stays clean  as opposed to it turning black in minutes and literally dripping out the mufflers with the apparently new and unworn rings I had to start with. I did bed them in on freshly honed bores with no additional lubrication.
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