Author Topic: Piston Rings  (Read 1768 times)

Online RichardL

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Piston Rings
« on: 24.12. 2007 19:18 »

I am about to get my barrels rebored up to .060 from .040 . Before I bought the pistons (Hap Jones 9:1), I bought a set of unopened Hepolite .060 rings, knowing someday I would need them. The pistons came with rings that I am assuming are not equal to the Hepolites in quality. Therefore, I would prefer to use the Hepolites. However, I am a little confused by one of the markings on the box that says "CR.10.5.1" This seems like it is implying that the rings are for 10.5:1 pistons, but I have never heard of rings specifically designed for a given compression ratio. Maybe they mean that they are good for up to 10.5:1. Does anyone know the answer to this? Another factor is that the box on the rings are in is still sealed as it was when it came from he factory. Of Course, parts are meant to be used. but it is going to hurt just a little to open this box.

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Offline a10gf

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Re: Piston Rings
« Reply #1 on: 25.12. 2007 13:04 »
On the spot, I'd say if the rings fit the pistons, don't worry about the writings, except, as far as I remember, text on the rings should face up. I understand the dilemma of opening up  original vintage boxes  ;)

For any rings, do the measurements for clearance. Then check the gap when fully compressed  adjust if necessary, and go ahead. If in doubt, use the ones that came with the pistons, and keep the heps for an eventual later swap if needed. Or keep them unopened and sell them on ebay in the future, for a fortune lol. Mount with gaps facing correctly, as I suppose is mentionned in the documentation.

Any corrections most welcome.

And yes, I have managed to break rings when fitting... one learns the hard way sometimes.

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Offline LJ.

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Re: Piston Rings
« Reply #2 on: 25.12. 2007 20:33 »

Any one fitting piston rings in cold sheds should heat the rings first, a tip that I was given the other day. I suppose it makes sense in that the metal becomes more flexible when warm rather than brittle when cold.
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1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red