Resistor and non-resistor plugs

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BrianK

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Maybe my multimeter has pooped the bed. BUT:

Just tested a few NGK spark plugs, old and new, for resistance. Be assured I did not misread the part numbers.

Old (used, not sure how much) BP7ES (non-resistor) - about 5.5 mega ohms.
New (used, a few hundred miles) BPR7ES (resistor) - about 14 (!) mega ohms.
New BP7ES/2412 - fresh from box; non-resistor - about 0.2 mega ohms.

Curiouser and curiouser.

The meter? Poor quality control? User error?
 
I am yes. Kilo ohms. But those readings are all on the same scale.

So the new BP7ES have the right (non-) resistance. The old BP7ES are supposed to be non-resistors, but have the resistance you'd expect from a resistor plug. And the new BPR7ES have WAY too much resistance.
 
BrianK said:
Maybe my multimeter has pooped the bed. BUT:

Just tested a few NGK spark plugs, old and new, for resistance. Be assured I did not misread the part numbers.

Old (used, not sure how much) BP7ES (non-resistor) - about 5.5 mega ohms.
New (used, a few hundred miles) BPR7ES (resistor) - about 14 (!) mega ohms.
New BP7ES/2412 - fresh from box; non-resistor - about 0.2 mega ohms.

Curiouser and curiouser.

The meter? Poor quality control? User error?
Click to expand...
A BP7ES, if measured correctly will read 0 ohms or it is bad.
A BPR7ES, if measured correct will read about 5 kilo ohms (5000 ohms)

A plug that measures 14 mega ohms (14,000,000 ohms) is unlikely to spark!

I'm guessing you're either not reading the meter correctly, not measuring the center electrode, or you meter is no good.
 
5000 ohm is the target number for a NGK resister plug. Ie 5 k ohm.

It's worthwhile reading their official website.

There are NGK fakes sold on EBay and Amazon

I have seen a good you tube video. Which I cannot find now 😤 which gives several ways to identify fakes. There are several ones online but I cannot find the really good professional quality video sorry.


From memory the fakes are 15 k ohm plus and some over 100 k ohms. So your 14 k one may be a fake.
 
I have a fairly large collection of plugs - I change frequently and always feel bad about throwing away "a perfectly good used plug." Guess I need to go through the box and start throwing away some.

The good news is that the ones I most recently bought, a decent quantity of BP7ES/2412s, ohm out correctly so those at least are good. I probably have some ersatz ones in there from various sources along the way.
 
This is a good video


He says 4 to 7 k ohm for good genuine NGK R resister plugs. Your 15 k one does not sound correct.
 
It's not the best video but it's pretty good. I'll do another search when I have time or maybe there is some thing on the NGK website.
 
This thread got me interested - so I tested some and found:

* 4 new NGK BPR7EIX were 4.79, 4.82, 4.58 & 4.76 k ohms
* 2 new Denso IW22 5307 were 4.54 & 4.14 k ohms

* the 2 from my bike (BPR7EIX with 3000 miles on them) 4.78 and 5.86 k ohms
* my leads (made from Green Spark Plug parts including NGK resistor caps) were 9.61 & 8.10 k ohms

I have Trispark and it handles the combined resistance (13 to 15 k ohms) very well
Cheers
Resistor and non-resistor plugs
 
robs ss said:
This thread got me interested - so I tested some and found:

* 4 new NGK BPR7EIX were 4.79, 4.82, 4.58 & 4.76 k ohms
* 2 new Denso IW22 5307 were 4.54 & 4.14 k ohms

* the 2 from my bike (BPR7EIX with 3000 miles on them) 4.78 and 5.86 k ohms
* my leads (made from Green Spark Plug parts including NGK resistor caps) were 9.61 & 8.10 k ohms

I have Trispark and it handles the combined resistance (13 to 15 k ohms) very well
Cheers
View attachment 116893
Click to expand...
Interesting. I have only used Pazon and he recommends either resister plugs or caps but not both.

Having said that I have seen street bikes happily use both with Pazon ignition.

I got interested in the genuine or not NGK plugs when I had to buy spares for a 7 R race bike. The plugs it was using cost over $100 NZ. About US $60. So I wanted to be sure I had real ones at that price. 😬😬😬
 
If the meter is ever suspect, besure to renew the on board battery (mine hasn't been changed in at least 2 decades 😱 ).
 
johnm said:
Interesting. I have only used Pazon and he recommends either resister plugs or caps but not both.

Having said that I have seen street bikes happily use both with Pazon ignition.

I got interested in the genuine or not NGK plugs when I had to buy spares for a 7 R race bike. The plugs it was using cost over $100 NZ. About US $60. So I wanted to be sure I had real ones at that price. 😬😬😬
Click to expand...
The odd thing is....I think you are more likely to get the real thing in a high end race plug, they don't sell in sufficient volume to make selling fakes pay!

And whilst I might question your spelling of resistor, I will certainly agree, resistor plug or resistor cap, but never both.
 
I pulled the plugs, also NGK BP7ESs (or sold and labeled as such, anyway) in my '72 Guzzi Eldorado today. One ohmed out at 150 ohms, and the other at 7.4 kilo ohms. Replaced with two from my stock that ohmed out correctly to near zero ohms (my multimeter has 0.1-0.2 of internal resistance), and I had to go through four to find those two.... binned the old ones and the non-conforming new ones. Airhead is next.

Funny, I thought I had enough BP7ESs in stock to last a lifetime but I'm running through them at quite a clip....
 
My Norton never did run any good with NGK (BP7ES) spark plugs within a week it always got a misfire so went back to the Champions N7YC, never had any problems with them except when they had that bad batch back in the late 70s and now running the Joe Hunt my plugs seen to last forever, when I found out non resistor plugs are being phased out I built up a stock of new N7YC plugs, should see me through.

Ashley
 
Four Denso VW22s just arrived - equivalent, but better spec, to NGK BPR7EIX.
I have a single coil so the dual rare earth terminals make sense. The EIX only have iridium on the centre electrode.
Tested resistance - all between 4.1 and 4.5K ohms.
One thing of note - unlike NGK, Denso crimp the aluminium nuts onto the top terminal.
All were preset to 0.028" and I will leave them there - I normally set to 0.025".
I will report back on any difference to the NGK.
Below are the NGKs I pulled out - not bad, but only 1300 miles on them.
Cheers
NGK BPR7EIX at 13,300 miles.JPG
 
Last edited:
robs ss said:
Four Denso VW22s just arrived - equivalent, but better spec, to NGK BPR7EIX.
I have a single coil so the dual rare earth terminals make sense. The EIX only have iridium on the centre electrode.
Tested resistance - all between 4.1 and 4.5K ohms.
One thing of note - unlike NGK, Denso crimp the aluminium nuts onto the top terminal.
All were preset to 0.028" and I will leave them there - I normally set to 0.025".
I will report back on any difference to the NGK.
Below are the NGKs I pulled out - not bad, but only 1300 miles on them.
Cheers
View attachment 117190
Click to expand...

The information I found said that the Denso vw22 spark plugs have an iridium tipped electrode and a platinum plated ground electrode, so they are not dual platinum... Or maybe I am just looking at a different plug..

edited to add: I guess that makes them rare earth metals. I was also was reading about dual irridium electrodes and wondering about trying them too..
 
Last edited:

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