Spark Plugs 02

Mark Savage · Jul 25, 2016

I've been looking up plug stuff again and came across this thread. spark-plugs-t10453.html#p117025

I've been using NGK BP7ES in my Commando but I have had a failure with duff plugs. I had heard that some NGKs had been counterfeited and was hoping that I hadn't got some as I have bought 4. I managed to borrow some NGK B6ES which got me going again.

So now when I came across this on the NOC I see that NGK B6ES might even be the correct ones? The Commando in question is a 1972 750 Roadster with a boyer. What do you reckon or should I continue to treat what I read on the NOC with suspicion?

http://www.nortonownersclub.org/support ... or-nortons

L.A.B. · Jul 25, 2016

Re: Spark Plugs

Dommie Nator said:
I've been using NGK BP7ES in my Commando but I have had a failure with duff plugs. I had heard that some NGKs had been counterfeited and was hoping that I hadn't got some as I have bought 4.

Plugs can foul for a variety of reasons, not necessarily because they are counterfeit but you can check:

http://www.ngk-sparkplugs.jp/english/techinfo/fake/

http://www.nortonownersclub.org/support/technical-support-general/spark-plugs-for-nortons
Commando B7ES W5D N7Y W22EP-U Combat / some 850s
Commando B6ES W7D N9Y W20EP-U Most 750s / 850s

Dommie Nator said:
What do you reckon or should I continue to treat what I read on the NOC with suspicion?

Yes, just a little, as BP6ES and BP7ES are the NGK equivalents of those other plugs!
http://www.sparkplug-crossreference.com ... K_PN/BP7ES
http://www.sparkplug-crossreference.com ... _PN/BP6ES/

That's not to say a B6ES or B7ES won't work, but personally, I'd stay with the 'BP' plugs. If you suffer any recurring BP7ES plug failures and the plugs are known to be genuine then the fault probably lies elsewhere.

Mark Savage · Jul 25, 2016

Thanks for the reply.

The failure symptoms was really bad misfiring under acceleration. I took them out and noticed they didn't spark between the centre and the end of the ground electrode but half way along which I have not seen before. I would have thought it would want to take the shortest route. This was after cleaning up. I've checked my plugs against fake lookalikes in the link and they seem genuine enough. I'll have a look at a few other things as they seem to soot up.

Danno · Jul 25, 2016

I found a stash of NOS Champion N4G plugs on fleabay and bought a box of 8. They were my plug of choice for the Nort back in the day and they still work great. The first two have outlasted 4 NGK iridiums, so it looks like the price I paid was well worth it.

kerinorton · Jul 25, 2016

Sounds like you have found the problem. New plugs are the order of the day. BTW BP6ES = N9YC and BP7ES = N7YC. If you are doing mostly town riding and dont gun it, then N9YC will be ok, but if you are doing serious riding, use the N7YC as these will run cooler.
Spark plugs can also become lazy [ even though they look perfect] Lazy plugs will cause misfiring, and can be especially bad on the over-run causing back firing which eventually results in broken throttle slides.

As a result of being caught on a big run without spare plugs, I now carry 2 new spares all the time.

Happy riding. Dereck

Nater_Potater · Jul 25, 2016

Dommie Nator said:
...they didn't spark between the centre and the end of the ground electrode but half way along which I have not seen before. ...(t)his was after cleaning up.

Either stubborn carbon deposits giving a path along the insulator side, or (more likely?) a cracked insulator. Both doing it? 'Not likely that both would crack at the same time, so I'm sticking to the carbon track theory.

Nathan

APRRSV · Jul 28, 2016

Is the RN7YC the proper resistive equivalent to the N7YC for use with electronic ignitions?

Ed

L.A.B. · Jul 28, 2016

APRRSV said:
Is the RN7YC the proper resistive equivalent to the N7YC for use with electronic ignitions?

http://www.gsparkplug.com/1x-champion-c ... pr7es.html

Spark Plug RN7YC Eqv to NGK BPR7ES
.
.
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Resistor Yes

APRRSV · Jul 28, 2016

Thanks L.A.B.

99cyclone · Jul 29, 2016

Danno said:
I found a stash of NOS Champion N4G plugs on fleabay and bought a box of 8. They were my plug of choice for the Nort back in the day and they still work great. The first two have outlasted 4 NGK iridiums, so it looks like the price I paid was well worth it.

Yes, the old Champion Gold Palladium plugs are the best. Too bad they don't make them anymore. I used to run them in 2 stroke MX bikes to prevent fouling. Today I run them in my old Brit bikes.

Velocettes are notoriously hard to start. Since installing an N4G and using a washer to index the electrode, starting is noticeably improved.

Spark Plugs 02

Mark Savage

L.A.B.

Moderator

Mark Savage

Danno

kerinorton

Nater_Potater

APRRSV

L.A.B.

Moderator

APRRSV

99cyclone

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