Is there such a thing as Chinese NGK plug knock offs?

Good info here on sparkplug internal resistance. Tempest manufactures high quality resistor type spark plugs for aircraft engines.
They advise against running with plugs that show high or infinite resistance.

https://www.qaa.com/resource-center...s-the-right-way-to-check-spark-plug-resistors

And some more discussion of rough running caused by high or infinite resistance plugs in Aircraft

https://blog.aopa.org/aopa/2015/03/19/champion-from-denial-to-acceptance/

Interesting stuff, that I never knew before thanks.

If (as happened to my NGK B8HS plugs in a non-Commando) the copper core doesn't make metal to contact with the top terminal, causing the meter to show infinite resistance, then you can't measure the resistance of the purpose-built resistor in the plug.

Its been a week of learning for me as well.
It seems that the problem of high internal resistance sparkplugs is well known in the piston engine aircraft world, somewhat known in the automotive world and pretty much unknown in motorcycle world.

I called NGK tech support to get their thoughts on high internal resistance of a new plug, ie should it be used.
Initially I was told that it was impossible to measure the internal resistance of a sparkplug with an ohmeter.
Then it was conceded that continuity could be checked and there should be continuity. The tech informed me that in all of his years at NGK checking thousands of plugs he had never seen one that did not have internal continuity!
When I told him that I have several here, he suggested that my meter was faulty.
That would have to be both of my meters as they both show the same readings +-.
So that went nowhere.

My Commando , which has always been a stellar runner with a steady idle, did not run great last fall. I joked that it had one half of the new car feature where the engine shuts off at a stop to save fuel.

It also had a slight surging action happening at cruising speed. In addition, the fuel consumption, which had been around 60 miles per Imperial gallon on a steady cruise dropped to under 50 .

I thought the problem was likely carb related and was about to order new Premieres.
Hot on the sparkplug idea, I pulled its plugs and checked them yesterday.These were new last fall, that's why I had earlier assumed the running issues were carb related.
One tested fine, the other showed infinite resistance.
Replaced those with new zero resistance plugs and voila, the smooth steady idle is back.
If the weather permits I'll take it for a run today to see if the surging is there or not.

Glen

The roads dried off so I went for a ride.
5 c here today so it was a fairly short ride, about 15 miles.
That was far enough to learn that the surging or hunting at cruising speed is gone. The idle is nice and steady as well.

Put the suspect plug back in and the rough / dieing idle returned. I didn't bother checking for the cruise problem, I am sure it would be back as well.

All caused by a faulty new NGK non fake plug that " sort of" works but shows infinite resistance.
I guess those aircraft mechanics have got it figured.

Glen

gortnipper said:

When I have had carb probless, the NGKs I was using fouled pretty quickly.

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It we hear it very often.

Peter William says that the spark CHAMPION N7Y, C or CC has of the being to make for commando so much they give good results including for the races.

Regrettably, copies and fakes, it is not because for sparks, many parts are made in China or made in India by companies GB or US for our English motorcycles,very bad quality and sizes.

worntorn said:

The tech informed me that in all of his years at NGK checking thousands of plugs he had never seen one that did not have internal continuity!

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He may feel compelled to toe some NGK party line or something.

I've seen several go open circuit after some miles and I only own one bike!

I haven't seen infinite or high resistance on a new plug: does he only test new ones? I'd hate to think he's lying.

I've even fixed some! Although the loose connection didn't prevent sparking, the notorious Boyer Micro Power ignition (no longer in use) was extraordinarily sensitive to HT RF interference. I removed the threaded terminal from where it's screwed/glued into the porcelain and packed aluminium foil up into it.

Anyway, I'm here to learn and I think I'll try another make of plug soon.

Been using the same set of iridiums now for 4 years, regular checks show no problems. Last year I came across two sets of fakes, the first set I could tell were fakes even in twilight, they seemed too light. The second set just were not finished the same when looked at closely. When the owners looked at mine, they could see straight away that they had fakes. Remember not to gap them, fit and forget. With the resistive version, do not use resistive lead or cap. wire wound lead and un-resistive cap are just ideal.

Bosch was the plug I used and trusted to be reliable, starting 45 years ago in dirt bikes, snowmobiles, (later ATV's), and street bikes. Chumpeens just didn't resist fouling in the old two strokes, compared to the Bosch. (JMWO) Then, later, NGK became so prolific, I transitioned into them as my go-to brand for convenience. NGK BP9ES is what I run in the Commando now. In over a quarter million miles in power sports, I can't remember a bad one (any brand) out of the box.

The voltage applied when making a resistance test is important. Most handheld multimeters use a 9V battery. Possibly there is some oxidation where the resistor contacts the electrode or attaching terminal inside the plug. This could cause a high resistance reading on a multimeter, where something like a megger which applies 500V or 1000V would blow through that oxidation and give you a true reading. I think the first time the plug fires it would accomplish the same thing. Would be a good test of this theory to try using one of those high resistance plugs in an engine for a few firings and measuring the resistance before and after with a multimeter.

Also wanted to mention that the 5K resistor plug caps could have the same problem. Worth checking.

Russ

concours said:

In over a quarter million miles in power sports, I can't remember a bad one (any brand) out of the box.

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I bought two open circuit plugs on Thursday. Ordered in 8 Champions, 6 tested ok.
I haven't called Federal Mogul/Champion yet but I can already hear the response.
They will probably tell me that my meter is bad or that I need a high voltage meter, not 9 volts.
That seems to be Champion's official line regarding their $500 per box aircraft plugs, which have shown problems with high resistance.
The FAA says the 9 volt test is sufficient.

Glen