NGK BP 7ES RIP

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With a dual output (dual tower) single coil, one spark fires from ground electrode to centre electrode, and the other spark fires the other way from centre electrode to ground electrode.

So for these coils, the precious metal tip on only one surface will only be beneficial on one side of the bike.

I like Densos, as I have a concern for the NGKs and Champions being counterfeit.

The VW22 has an iridium centre electrode and platinum ground electrode, so to me is a good candidate for dual output single coils.

The IW22 has an iridium centre electrode and nickel plated ground electrode (same as plug housing) so is ideal if you are running two coils. Perfectly fine for a standard two coil setup.

The other solution would be to swap plugs from left to right whenever you take them out for cleaning or inspection.


Denso have started doing a twin tipped iridium plug (they call it the TT) but it is not yet available in our heat range.

I also checked NGK a while back - looking at their double platinum and the new ruthenium plugs, and they didn’t have a suitable plug for our bikes at the time.


This is not a major problem, it’s purely sweating the small stuff.
But I do think it’s good for people to understand how their ignitions work and that if you have selected and paid extra for precious metal plugs (like iridium or platinum) believing there is a benefit of longer service life and slower electrode erosion, you are made aware of how a dual tower single coil works and that you may be foregoing any benefit.

I know several very reputable companies that ship the NGK ‘R’ plugs as part of their single coil packages.



This has nothing to do with wasted spark ignition, where you get a firing plug on both sides whether you are on the combustion stroke or not.
That’s just the behaviour of most electronic ignitions versus standard points where you only get a spark on the cylinder that is on the combustion stroke.

This is great info, Denso's not available locally here and are CRAZY expensive online. I'm running iridiums now but even they are pricey, so I just ordered a box of plain old copper core BPR7ES for $30, will be switching back
 
So, ignoring long life for a moment, what about sparking performance...

In our bikes, typically running an EI and often a twin outlet coil, is there any difference in spark performance between standard and exotic plugs?

As I mentioned above, my humble old fairly stock T140 (which burns a bit of oil) definitely seems to start and run better (mainly noticeable at low speeds) on standard plugs.

Is it my imagination?
 
@Fast Eddie my feeling is that on our bikes, the biggest, noticeable performance increase of these plugs is delivered to us by the good old placebo effect.


While most of the plug manufacturers claim a hotter spark and less time to arc I do feel that would be difficult to benefit from on a Commando.

If the fancy plugs spark quicker, that would mean that on our bikes you'd be sparking further before top dead centre.
Whereas a modern engine laden with sensors would compensate for this instantly, we would have to play with the timing on our bikes to dial in the optimum with a strobe light.


I'm really not sure how this maps on to the difference you see with your Trumpet?
The bikes are not that dissimilar, and the heads are the same shape.
My only thought would be around your piston shape - ie is your air and fuel mixture in the same place relative to the tip of the spark plug as the piston comes up compared to how it is on the Commando?
 
any truth to this rumor? since todays gasoline differs from the stuff available in the 70's, aside from the ethanol crap, i've heard it's better to run plugs one (1) heat range hotter from normal spec - assuming factory stock, street applications. for example, if a heat range "7" is called out, it's better to run an "8".

here's a pic of one of my plugs - N7YC champion. there's about 400 miles on the plugs - carbs at stock jetting and pulled after steady state, 1/4 throttle run. i'm thinking i'm in the ballpark on mixture and heat range - comments....

NGK BP 7ES RIP
 
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Maybe a tad rich in theory perhaps, but in reality I’d personally be VERY happy with that plug Joe...
 
Maybe a tad rich in theory perhaps, but in reality I’d personally be VERY happy with that plug Joe...
do you think there would be any benefit by going to a slightly hotter plug? i'm thinking since most heat is dissipated through the outer threaded electrode, a slightly hotter plug might tend to slow the build up of those outer electrode deposits - ???? then again, I have fairly easy starts w/ no noticeable performance issues - probably should leave well enough alone. .
 
I've got B8's in my Triumph which I believe are equivalent to the N3's originally specified, but almost every other triumph owner I know is running B7's
So, ignoring long life for a moment, what about sparking performance...

In our bikes, typically running an EI and often a twin outlet coil, is there any difference in spark performance between standard and exotic plugs?

As I mentioned above, my humble old fairly stock T140 (which burns a bit of oil) definitely seems to start and run better (mainly noticeable at low speeds) on standard plugs.

Is it my imagination?

Are you running N3s or B8s? Projected or non projected? For years now I've been running B8s, but it seems the consensus is that these are a bit on the cold side (equivalent to N3), and mine, though not fouled, definitely suggest they are indeed a tad cold , so I will be trying a B7 projected when they arrive.
 
It depends which year Triumph, splayed port T140s and just about most Triumphs I think, use a champion N3, but the parallel port T140E runs cooler and uses N5.

N3s in my T140E foul like crazy !

I‘m running N5 at present, also tried some NGK B6ES, both seem to perform the same to me.

I tried fancy pants Denso IW20s but reckon the N5s and B6ES run better...

Currently thinking I’ll stick with the Champions.
 
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NGK's numbering is opposite everyone else.
B8 is colder than B7,
B6 is hotter than B7.
 
In our bikes, typically running an EI and often a twin outlet coil, is there any difference in spark performance between standard and exotic plugs?

My experience leads me to believe that the plugs with the small diameter center electrodes may have a broader heat range but also produce a smaller spark; they may also be more resistant to fouling. I tried the Champion "G" plugs in a Honda CB 750 K2 and found that hot or cold starting took longer. I tried the iridium plugs with the same results; I'll stick to standard design plugs.

Best.
 
any truth to this rumor? since todays gasoline differs from the stuff available in the 70's, aside from the ethanol crap, i've heard it's better to run plugs one (1) heat range hotter from normal spec - assuming factory stock, street applications. for example, if a heat range "7" is called out, it's better to run an "8".

here's a pic of one of my plugs - N7YC champion. there's about 400 miles on the plugs - carbs at stock jetting and pulled after steady state, 1/4 throttle run. i'm thinking i'm in the ballpark on mixture and heat range - comments....

NGK BP 7ES RIP
Too rich for optimum power.....
 
Something I read years ago, before the internet, about the 'Platinum' plug.
At the time, Platinum was the exotic.
Basically saying it will last longer, resist fouling, however has a shorter spark duration.
The article concluded that in some applications, Copper Core plugs may produce more power.

Don't know where I read it, can't confirm it. Just throwing it out there.
Maybe some experts with real knowledge can elaborate.


Edit... The Platinum plug was the answer for my High Mileage, oil burning 460 Pick up back in the day.
 
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B8s from the triumph left and BPR7 iridiums from the norton right. The NGK cross reference chart actually shows the B7 as a match for the N3 rather than the B8, so I'm not sure why I ended up with these in the first place
NGK BP 7ES RIP
 
N3 is colder than N4 Champion wise. NGK chart says to use an BP8es for an N3 application. Norton gets the 7 so that would be a Champion N4 if using Champs for the Commando? No they get N7. Sometimes it is hard to believe the interchange charts.
 
If the fancy plugs spark quicker, that would mean that on our bikes you'd be sparking further before top dead centre.
LOL, no. A spark plug can't affect timing.

Firing sooner means that it takes less voltage to bridge the gap. The sooner the plug fires (we're talking sub-microseconds) the more of the coil's stored energy will be delivered to the spark. More energy means more heat to ignite the mixture and longer duration spark for more complete combustion.

Materials choice does affect this, but I'm pretty sure that plug manufacturers are targeting long life more than spark efficiency.
 
@maylar I appreciate it’s only fractions of a second.

But let’s say that timing is set at 28 degrees before top dead centre.
And let’s say a fancy pants plug fires ‘more immediately’ versus a standard plug that fires a little later (based on the manufacturers marketing guff)

So in that scenario, if you timed the bike on the standard plug, then put in your new fancy pants plug, the piston would not be as near to top dead centre before firing.

Relatively speaking, there is a huge amount of piston movement for one degree of crank rotation as You start to approach top dead centre.


Kind of like the difference between a projected plug vs standard plug could be a degree of timing between them.


...all thinking out loud of course - I’m just trying to think of reasons why an irridium plug would behave differently to a standard copper core one.
 
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And let’s say a fancy pants plug fires ‘more immediately’ versus a standard plug that fires a little later (based on the manufacturers marketing guff)

So in that scenario, if you timed the bike on the standard plug, then put in your new fancy pants plug, the piston would not be as near to top dead centre before firing.
You're an electrical sorta guy, so I'm sure this won't be lost on you -

Spark voltage is AC - a damped sinusoid decaying at an exponential rate. "Rule of thumb" is that it takes about 12,000 volts to bridge a .025 plug gap in an 8.5:1 combustion chamber.

Because of certain phenomenon of Physics, called thermionic emissions, free electrons are generated by the hot center electrode of a spark plug. This is the same principle used in the cathode of a vacuum tube (valves to the Brits). This effect depends greatly on the choice of materials.

Because the center electrode has free electrons, making it negative reduces the voltage required to bridge the gap. This is what the polarity markings on an ignition coil are for - to insure that the initial rising edge of the plug voltage is negative, thereby firing the plug earlier on the rising edge of the first cycle and capturing the maximum energy from the coil.

The timing difference from one plug to another is microscopic.
 
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