Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board NGK plugs

This is from Dan at Franz and Grubb Engine;

NGK has stopped production of some popular NON RESISTOR plugs. These
plugs include *B6ES, B7ES, B8ES, B9ES, *and also the*B6HS, B7HS, B8HS,
B9HS, *etc. These part numbers are being superseded to RESISTOR type plugs.

*According to NGK, B8ES is now replaced by BR8ES.*

I spoke with a technical advisor at NGK USA about the change, and was
advised this change would work for "most applications". When asked about
vintage motorcycles with magneto ignitions, the reply was "except for
that application"

I use non resistor NGK competition plugs...heat ranges 7 on up.....But now I'm using non resistor Denso plugs in my street bike.

I use DENSO IW24's. Best plug ever.

I'm curious why the NGK rep would say a resistor plug won't work with a magneto. Piston aircraft run magneto and resistor plugs all the time.

Would I run a non-resistor plug in that application if I could? Sure. But I also wouldn't be scared to give a resistor plug a shot and see what happens.

DENSO did not say that NGK did.

Are you comparing apples with apples?

1950's motorcycle magnetos with 1950's plane magnetos? or with later plane magnetos?

Recommended plug gap on 50's bike mags were generally ~18-20 thou, I assume there was a good reason for this.

Adding resistance to this doesn't sound like a great idea.

Well DENSO did say not to use their plugs in airplanes, helicopters or drones. For more clarity ask DENSO or NGK or both.

Oops, I'm not sure why I wrote one when I meant the other. It's fixed.

In my opinion, yes. The magnetos for aircraft haven't changed from the 1950s until now. The recommended gaps are the same too.

If an aircraft can run at altitude with high resistance plugs (some of them being out of spec due to very high resistance) I'd expect that any bike magneto would be just fine with a typical resistor spark plug.

Nowhere did I say that adding resistance was a good idea. I just said I wouldn't be scared of it.

I only tried ND plugs once when the local shop put them in. Bike ran like crap until I put in proper N3s.

I never had luck with Japanese plugs.

My experience (YEARS ago, I'll admit) was that they were short-lived in a motorcycle.
They went bad at about 1,000 miles.

I'm the opposite. Never liked Champions. NGK was the only Asian thing on my bikes.

Strange that David i once had a Jap bike that wouldn't run on NGK only N3s

OK. Here's my story:

I bought a new Honda CL-77 scrambler (my first bike) in 1966.
It was my daily transportation, even in the Illinois winter.

The bike had problems with NGK plugs, which it came stock with.
I went through several sets in the first 3,000 miles.

I was working at a NAPA auto parts dealership at that time.
I asked the parts counter man if he had an interchange for the plugs.
He had interchanges for both Champion and AC Delco.

I bought TWO pairs of AC plugs, put one pair in the bike, kept the other pair as spares.

When I sold the bike 8 months later, I gave the unused second pair to the new owner.

The bike had about 10,000 miles on it at that time.

I have NEVER used Japanese-made plugs since.

Based on my personal experience, I think both the Champion and NGK products have been superior to the other at various times in history. When I first started working on cars and motorcycles many years ago, the Champions seemed to work better and last longer. About a decade later, the NGK seemed to be better. In recent times, I think they’re about equal. I bought a Triumph Spitfire (car) a while back and the previous owner had done a “tune up” on it that included Champions. Those spark plugs have suffered a ton of abuse while troubleshooting a sunk carburetor float. I had some NGKs in it during the same period with similar results. I’m still running the Champions, because they’re fine and I’m too lazy to swap them out for a fresh set of plugs.


For those wanting to run NGKs and stay away from resistor plugs, you might look at the NGK Racing product line. Stock number 4091 should be heat range 7 and 4554 should be heat range 8.

im just going to buy a bunch of B8s and B9s while theyre still available

Havent used Champion since the early 80s , last set of NGKs came out of a bin, stilll OK 15 K later.
Champion were bad in 1977, I never forgave them.
I have a Goldstar mate who uses KLGs , FFS.. use it if it works.