G80CS Piston rings

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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CSBill
Posts: 6
Joined: Fri Jul 29, 2022 10:50 pm
Location: Texas USA

G80CS Piston rings

Post by CSBill »

I have a Welworthy piston, that is fitted to my +.040" G80CS (long stroke) barrel. The J.P. rings that were provided are too deep for the grooves in the piston and therefore stand proud of the piston by approx .030". A very talented person would cut the grooves a bit deeper, I I would rather find the correct ring set, .111" radial depth. Any advise as to where to search woudlbe greatly appreciated.
SPRIDDLER
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Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: G80CS Piston rings

Post by SPRIDDLER »

Welcome to the club and Forums, Bill.
I don't know of anywhere in the U.S.A. although I think there's still the original importer of the G80CS bikes in the USA but can't think of his name at the moment. No doubt someone will add that info if you don't already know them.
I may be thinking of Walridge Motors in Canada who I believe have spares for British Classic bikes.

https://www.walridge.com/

In the U.K. Thorntons are a 'Go to' supplier for pistons and rings and very helpful. I'd suggest asking them by email with details of your piston.

https://www.fwthornton.co.uk/?gclid=Cjw ... y4QAvD_BwE

You are probably aware that the Club spares dep't stocks complete pistons and some ring sets.

https://www.amoc-parts.com//store/comer ... r2=&user3=
'There is a tide in the affairs of men
Which taken at the flood............'
g80csp11
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Posts: 1567
Joined: Mon Jan 01, 1990 12:00 am
Location: WEST SUSSEX UK

Re: G80CS Piston rings

Post by g80csp11 »

you need imperial rings , if you are stuck send cox and turner a message , they can do a set . obviously postage will be a problem
If not search for a set of original on ebay
All modern pistons will have metric rings

https://www.coxandturner.co.uk/piston-rings/
CSBill
Posts: 6
Joined: Fri Jul 29, 2022 10:50 pm
Location: Texas USA

Re: G80CS Piston rings

Post by CSBill »

No joy at the AMOC, Thorton, while Walridge sent the worng set and has no access to the correct ones. Have submitted an enquiry to Cox & Turner to see what they might have.
Best,
Bill
g80csp11
Member
Posts: 1567
Joined: Mon Jan 01, 1990 12:00 am
Location: WEST SUSSEX UK

Re: G80CS Piston rings

Post by g80csp11 »

absolutely guarantee cox and turner will sort it out , always come up trumps
CSBill
Posts: 6
Joined: Fri Jul 29, 2022 10:50 pm
Location: Texas USA

Re: G80CS Piston rings

Post by CSBill »

All sorted, found a skilled machinist able to cut my Welworthy piston to fit the JP rings. Thanks to all for your input.
mdt-son
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Joined: Wed Feb 01, 2012 1:22 pm
Location: Vestland NORWAY

Re: G80CS Piston rings

Post by mdt-son »

CSBill,
Please share details. What's the ordering number of the JP rings (compression and oil scraper rings)?

I noticed JP supplies pistons for 1956-59 CS engines. Piston rings are 2x1/16" and 1x4mm scraper. 1960- on pistons have the same rings, I guess. This is specification shared by the late 650CSR as well as the BSA DBD34.

I wonder if gapless rings can be made to fit. They are particularly interesting for high CR engines.
Cheers,
Knut
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