Author Topic: Piston Ring Taper  (Read 582 times)

Online RichardL

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Piston Ring Taper
« on: 29.03. 2015 18:31 »
Gents,

This has been mentioned a couple of times here on the forum, but I'm just checking for the latest attitude about it.

I was about to drop my barrels over the pistons when I took a look at the box for the rings. From Aerco via SRM, "Manufacturer AE Hepworth & Grandage, To Suit BSA A10, Premium Quality Ground Taper Faced Piston Rings". Oops, better check that they are right-side-up. Well, there is no clear indication which way is up. The marking "AE - 60" is clearly visible on one surface, so I would guess that marking would go up, but I'd like an authoritative an definitive answer before going with my foolish guesswork. Anyone care to advise? Otherwise, and maybe even-if, I'll call SRM tomorrow morning and ask them. I certainly could not see any taper. Even if I could, I'm not sure which way it should go.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline muskrat

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Re: Piston Ring Taper
« Reply #1 on: 29.03. 2015 18:51 »
G'day Richard. Writing side up. Taper rings bed in quicker than flat face rings.
Gotta go, Motogp has started! 4.30am here.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Muskys Plunger A7

Online bsa-bill

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Re: Piston Ring Taper
« Reply #2 on: 29.03. 2015 21:14 »
Good Question Richard I've had the same experience myself and always wondered, Thanks Muscky and  I watched the Moto GP ,1600 here on BT sport, bit of a palaver, have to get it on my tablet and connect via HDMI to the tv and a dodgy mini HDMI on the tablet makes for a bit of frustration but "way to go" Valentino
All the best - Bill
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1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online bsa-bill

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Re: Piston Ring Taper
« Reply #3 on: 30.03. 2015 20:33 »
Muskrat - do I owe you an apology, did I intimate the winner of race before you'd seen it, thought later about time zones or recorded programmes and maybe I'd blabbed a bit.
Anyway damn fine racing, perhaps not quite as hair raising as Foggy on a Dook but a well thoughout race from Mr Rossi
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline muskrat

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Re: Piston Ring Taper
« Reply #4 on: 31.03. 2015 02:17 »
No worries Bill. I think we get it live on free to air, just have to put up with the adds.
Nice to see the Ducks do well and that MM is something else.
Back on topic: The taper is thick at the bottom (sounds like me) so the first few revs gets rid of most of the assembly oil.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online RichardL

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Re: Piston Ring Taper
« Reply #5 on: 31.03. 2015 03:49 »
Many thanks, Muskrat. The barrels went on today and, yay!, without breaking any rings. It's amazing what you can do when you're careful and take your time. This fix is going to be an interesting experiment. No question that the bores and ring gaps are both a couple of thou too big. The problem is, bored to 0.060" over, the choice was, either, experiment with $60 worth of new rings, or, maybe, a grand worth of new parts and machining. Figured the rings were worth a try. Yes, it won't be that long before the inevitable, but I'll be happy if it is put off a couple of years (hmmm? when the parts cost will be triple?) 

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline muskrat

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Re: Piston Ring Taper
« Reply #6 on: 31.03. 2015 04:18 »
Don't feel so bad mate. Two years ago I nipped up the '51. I put the bad piston in the good bore and the good piston in the bad bore, Both with new rings. Just did a 550 mile/weekend ride, no worries. I used to cringe at the idea!!
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Muskys Plunger A7

Online Triton Thrasher

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Re: Piston Ring Taper
« Reply #7 on: 31.03. 2015 09:58 »
Many thanks, Muskrat. The barrels went on today and, yay!, without breaking any rings. It's amazing what you can do when you're careful and take your time. This fix is going to be an interesting experiment. No question that the bores and ring gaps are both a couple of thou too big. The problem is, bored to 0.060" over, the choice was, either, experiment with $60 worth of new rings, or, maybe, a grand worth of new parts and machining. Figured the rings were worth a try. Yes, it won't be that long before the inevitable, but I'll be happy if it is put off a couple of years (hmmm? when the parts cost will be triple?) 

Richard L.

Bigger ring gaps don't matter. Slightly big piston clearances probably won't matter.

Run it in on cheap oil, or running-in oil, until it stops smoking.  If the rings bed in, it'll be many thousands of miles before you're troubled by any wear.


Offline duTch

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Re: Piston Ring Taper
« Reply #8 on: 31.03. 2015 10:56 »

 Saw this the other morning just as the race started...
 I have my ring gaps written somewhere, I think around 15 thou(?) but running fine- will get back on that one...

 ......and then at about lap three, there was this enormous farqquueeiing bang.....and sparks and everything like a ten gaziggillionmega-amp welder outside for a while, and the power went off...

 I knew it was shaping for a good race, but geez..that's powerfull.!!   had a look outside, and the powerpole was on fire...so took some piccies, and maybe a video, and then the power came back on, so went back to the coverage...

 Good to see the Dook adding some angst in there, at least as a consolation 2+3 ain't bad....!!!!

 then I headed off to work- good timing

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Online bsa-bill

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Re: Piston Ring Taper
« Reply #9 on: 31.03. 2015 11:13 »
Quote
there was this enormous farqquueeiing bang.....and sparks and everything like a ten gaziggillionmega-amp welder outside for a while,
Quote
had a look outside, and the powerpole was on fire.

Did you get a photo of that big hand in the sky with finger pointing  *lol*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco