Using NOS plugs - Champion N57R

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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Scout63
Posts: 18
Joined: Wed May 06, 2020 3:58 am
Location: Massachusetts, USA

Using NOS plugs - Champion N57R

Post by Scout63 »

I pulled the plug from my new to me 1961 G80CS and it is a clean Champion N57R. I have never seen this type of plug with a shrouded electrode. I bought a box of 10 of these plugs unused in original packaging on eBay as I couldn't find them new. Is it ok to use old unused plugs? Is there a better plug for this model? Thanks.
Ben Zehnder - Orleans, MA USA
1961 Matchless G80CS
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1978 Yamaha SR500
1979 Moto Guzzi V1000G5 - current project
bjorn
Member
Posts: 69
Joined: Mon Jan 01, 1990 12:00 am
Location: NORWAY

Re: Using NOS plugs - Champion N57R

Post by bjorn »

Hi Ben,
The N57R is for racing only, with an open pipe. The "R" stands for retracted gap. These plugs are good, but can oil up if you have a motor that burns a lot of oil. The N57R corresponds to an NGK B10.

For street use on a G80CS with a silencer, I use a Champion N3 which corresponds to an NGK B7.

regards
Bjørn
Scout63
Posts: 18
Joined: Wed May 06, 2020 3:58 am
Location: Massachusetts, USA

Re: Using NOS plugs - Champion N57R

Post by Scout63 »

Thanks Bjorn. Ben
Ben Zehnder - Orleans, MA USA
1961 Matchless G80CS
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1978 Yamaha SR500
1979 Moto Guzzi V1000G5 - current project
gtx469
Posts: 9
Joined: Thu Mar 19, 2020 11:47 pm
Location: North Lanarkshire UK

Re: Using NOS plugs - Champion N57R

Post by gtx469 »

A good N3C plug replacement I run in my 61 Matchless G9 twin and also my BSA Lightning 650 is the E3.18 plug. never had a spark issue with these bad boys. Its a direct replacement for the N3
Larry Larivee
jmbradford
Member
Posts: 24
Joined: Mon Jan 01, 1990 12:00 am
Location: MIDDLESEX UK

Re: Using NOS plugs - Champion N57R

Post by jmbradford »

These recessed plugs were designed for use with the CS heads that have the firing slot in the head as there is a risk of compressing the bottom electrode of a normal spark plug with these heads. I have used several NOS N57R in the past and they work OK , they might be a bit cold for some road use and are not to easy to start if oiled or flooded.A good magneto is a must for easy starting.An FE220 is similar style plug which you will see mentioned in the books too.
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