spark plugs

derek

Well Known and Active Forum User
VOC Member
Which is considered the best plug for a Comet with magneto.
I believe that fine wire NGK plugs operate at a lower votage, It was recommended to use a B6EV : But they are not now available.Thanks Derek.
 

Alan J

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VOC Member
I use NGK BP7ES in all my bikes! Old B.S.A. A.J.S, Morini and "me vin" the best all round plugs there are!! pity they are from "nipon!"
 

roy the mechanic

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VOC Member
N G K bp7es sounds a bit too much. the rap runs bp6es,all depends how oily you motor is. Techniv is dead right, No supressors of any kind with a "prince of darkness" mag! Roy.
 

Tom Gaynor

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VOC Member
NGK's recommendation for Rapides, Shadows, and Lightnings (and the single equivalents) is the BP6 - I have an obsolete NGK plugs booklet which gives recommendations for every old bike known to man. Grade 6 plugs are recommended for virtually everything. However if your plugs are oily, and you don't want a rebore and new valveguides just yet, a twin will run all day on the hotter BP5, which is hot enough to burn the oil off. (I've since bitten the bullet so have reverted to 6's again.
Caveat: I've been using NGK since 1974 with no problems. In the last 5 years I've had 5 fail, 4 of them in the last 2 years, all BP6 type, and all four almost new - mostly 2 or 300 miles. The last one was yesterday, after about 50 miles. It still has shiny plating on the thread.
 

mercurycrest

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VOC Member
I've been using Champion N-5c (which are now re-numbered 120c) for the last thirty plus years. I used to throw them out and replace them once a year. Npw, I just replace them with a cleaned pair and run last year's through the glass beader, check the gap and store for the next plug change. I doubt if I've bought a plug in at least the last five years.

Cheers, John
 

Tom Gaynor

Well Known and Active Forum User
VOC Member
Mag on the Vincent (two plugs) coil on the Sunbeam S7 (two plugs), and electronic on the Ducati. And jumping ahead, nothing wrong with any of them. What is odd is that none of my old NGK plugs have EVER failed. Maybe they've been "improved"....
 

Tnecniv Edipar

Well Known and Active Forum User
Non-VOC Member
Frequently failing plugs can be a sign of weak spark. It's difficult to know a mag is ok unless it's checked on a test rig. Mags do need regular servicing to maintain them at full performance . Mag servicing was generally mentioned in owners manuals , Lucas & Miller had service exchange schemes for customer convenience.
 
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