resistor and non resistor spark plugs

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A friend uses a Joe Hunt magneto on his Norton. After calling JH the heartily recommend a NON RESISTOR spark plug. Now that Champion and NGK no longer produce the non resistor type, Who does?
 

Time Warp

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I thought any NGK plug without an R in the spec was non resistor.
I have the opposite and need find NGK non resistor caps to suit Denso R plugs.

There seems to be non resistor in both those brands.
 
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marshg246

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A friend uses a Joe Hunt magneto on his Norton. After calling JH the heartily recommend a NON RESISTOR spark plug. Now that Champion and NGK no longer produce the non resistor type, Who does?
Amazon has both in stock.
 

fiatfan

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Did not know that you could unscrew the top of the plug..... interesting.
 
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Did JH also recommend using stainless wire core plug wires?

NGK produces V-Power Racing series non-resistor plugs for automobiles with the right reach, thread pitch, and heat range to work in a Norton engine. Gotta do your homework though. Example is a R5671A-7.

Back when I was a youth, we had to unscrew the top on Champion plugs for some plug wire sets. Dirt bikes I think, but probably some older cars as well.
 
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Copper core plug wires are fine. I love Magnetos with the new powerfull rare earth magnets and always use non resistor plugs, You should also gap the plugs down to about .018" for a mag - lot of people miss that.
 

phippsy

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I thought any NGK plug without an R in the spec was non resistor.
I have the opposite and need find NGK non resistor caps to suit Denso R plugs.

There seems to be non resistor in both those brands.
Not NGK but RGM sell non resistor caps (black rubber)
 
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When I heard about non resistor plugs being phased out I went and build up my supply of N7YC and now have enough to last a life time for my Norton and JH maggie as well I also have a turne up kit from JH comes with new spark plug leads, condenser and point's in the kit and yes plugs set at .018" gap for the plugs, the good thing with running a new JH maggie the plugs run cleaner and get a very long life out of the plugs, so far I have over 30k miles on my plugs, they look and run as good as the day I put them in, I pull them out on service but they are so good I put them back in without touching them, no carbon build up at all, and the best thing my Norton starts on first kick every time and only 1/2 a swing on the kicker when the bike has been run for the day, I have ran the older JH on my old Triumph and the new JH is even better and no need to rely on a battery.
So stock up on your non resistor plugs while they are still in stock.

Ashley
 
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I like the NGK plug caps but unfortunately they are all 5K ohms. The other day I had one come apart in use (the only one, ever) and a resistor fell out. It did not look repairable but not sure. Tonight I will pull apart an NGK iridium plug
 
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What a terrible quality video. But an interesting idea.
I wonder how long the loosely reassembled spark plug would last on a shaking Norton Commando?
 

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I recall reading a Norton Owners Club article on ignition systems and on topic of resistance, it stated even at 10k Ohms the drop in HT voltage is not significant even for our less capable coils. Higher resistance also increases the duration of the spark's plasma stream, which can help with more complete burning.
 
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Hmmm...just wondering why a magneto in a normally aspirated engine would specify such a narrow plug gap. A narrow gap is common for forced induction but naturally aspirated engines do best with the widest gap the ignition system can support. For best performance you usually you try to increase the gap over stock - again, based on whatever the ignition system can handle.
 

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Not NGK but RGM sell non resistor caps (black rubber)

Thanks.

#


"Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. It is for this reason that most racing plugs are non-resistor types."

It might be worth noting modern spark plugs are for long term service in engines that have superior (or vastly different) combustion chambers and fuel systems to things from 50 years ago.
 
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I have run NGK BP8's in both resistor and non-resistor versions and couldn't tell a bit of difference in starting or performance. Before we get into the sky is falling mode how about a few more direct comparisons on the same bike.
 

fiatfan

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Details on the NGK plug Schwany mentioned. They say the center electrode is "non-projected". Is that right?

ngk norton.jpg
 
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FWIW - there is no "hotter" or "more powerful" spark. The spark delivered is whatever it takes to jump the gap, which varies with engine load. IOW, if you have an ignition system that is capable of delivering, say, 50k volts, and it takes 15k volts to jump the gap, 15k volts is the "spark" that is delivered. IF there is enough voltage to jump the gap, the "extra" voltage does nothing to "increase" the power/heat of the spark. What a higher voltage secondary DOES do is allow the spark to jump larger gaps which reduces maintenance, increases the ability to fire though fouling, and allows a larger gap to be run.

Let's say you are running suppression wires AND suppression plugs. If the system can generate the spark to jump the gap at all phase of engine load, then replacing the wires/plugs (both or either) with non-suppressed components will make absolutely no difference.
 
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