Spark plug question

[millerdog]

I have a plug question. I’m currently running a Newtronic optical ignition, withe Dyna 5 ohm coils, and resistor wires. The plug caps are NGK, with the resistors removed. I’m running NGK DPR8EA9 plugs in it. Does this sound like a good setup? Or, should I be using a different plug? It runs pretty good but, I’m wondering if it might run better with the factory correct plugs, or some other non resistor plugs.

[Oldewing]

They plugs look ok? running well?

You system sounds correct for most applications...

[millerdog]

They plugs look ok? running well?

You system sounds correct for most applications...

The plugs look good however, I took a trip to the mountains last weekend, and up around 5000 feet, it started acting like it wouldn’t take any gas. I had to keep the revs up, to keep it from sputtering. First time it’s ever done that. When we started coming down, it ran better and better. I’ve had this bike up there many times with no problems. It’s just got me thinking. Probably too much. Lol

[Rat]

There is considerable controversy around removing those resistors, some say they contribute to proper ignition performance .... can’t find a link right now .... something described as 'electrical back pressure' ....
Also means you don’t need resistor plugs ....

Gord

[Track T 2411]

I can't say it would solve your altitude issue, but I would switch to the non resistor plugs if you're keeping the resistor wires, unless you have a radio/ stereo on your bike. Mike Nixon has a thread in his 'spot' where he discusses the resistor and its purpose...

[gltriker]

There is considerable controversy around removing those resistors, some say they contribute to proper ignition performance .... can’t find a link right now .... something described as 'electrical back pressure' ....
Also means you don’t need resistor plugs ....

Gord

Maybe this snippet from another Topic last week ?

Snip

"Now I’ll add that the 5k ohms is the resistance across the resistor in the plug cap and years ago there was a lot of people that just replaced & preached substituting a piece of brass or copper rod for the resistor, mostly as a fix for the supposed (incorrectly) eliminating a piece of the evil emissions. Don’t do it!

Years ago I talked to several spark plug/ignition reps/techs (at NGK & Champion) who all said the exact same thing in that the resistor in the cap is a necessary piece to properly fill the coils, think of it as electrical back pressure, you gotta have it. Anyway check your plug caps, and if you have an inductive timing light that clamps on the wire put it on the #3 wire and see if it triggers if not and the plug cap is good then you have either a bad wire or coil. My .02"

End of snip.

[Rat]

Yup .... thanks Cliff

Gord

[redglbx]

Well let’s add abit to my snip attached above. The oe ignition coils were designed to properly charge/fill with the 5k ohm plug caps so if you eliminate them or use resistor plugs you need that5k ohm resistance to properly charge the coils which can be done with either the caps or plugs in my opinion.

So will running both the caps and resistor plugs cause problems or charge the coils more ? I don’t know ! I think I need to call the NGK tech guy’s and ask and-isn’t the answer here but I’ll add that I’ve been running the caps & resistor plugs fora long time w/o any noticeable negative effects which is odd because if those plug caps get over the stated 5k ohms you get all kinds of mysterious little miss’s and such, so you’d think increasing the resistance with plugs should do the same but I haven’t seen that but have had problems with slightly over 5k on the caps.

Also while we’re talking ignitions a huge misconception is that using the “hi” performance coils really boists the output across the board but actually it only gives you better power down in the low rpm’s and actually tapers off considerably with rpm. So why does that help in any way ? Well the main benefit is quicker starting and keeping the plugs cleaner & firing in. The low rpm ranges. Remember that our Keihin carbs are quite lean down low, below about 2200/2400 rpm about 15-15.5 to 1 a/f ratio (very hard to ignite) and then goes pig rich in the 10-10.5 to 1 a/f ratio, but higher rpms require almost no spark to ignite the mixture.

Anyway, I’ll try to call the NGK tech guy’s and get back on the resistance thing. Inquiring minds wanna know !

[CYBORG]

I understand the math of all the previous posts on this matter. I would offer that the 1200 coils, without resistor or stock wires, and iridium plugs, Worked great . And that was on my 78 before I changed to the C5 system, which came with it's own coil.
however, on my 1200 I run stock 1200 coils, with Carbon core wires which have spark plug ends incorporated. Pretty much going against everything that has been excepted as correct. And it runs great. AT all RPM's. Again with iridium plugs. Just thought I would throw that in the mix.

[gltriker]

Well let’s add abit to my snip attached above. The oe ignition coils were designed to properly charge/fill with the 5k ohm plug caps so if you eliminate them or use resistor plugs you need that5k ohm resistance to properly charge the coils which can be done with either the caps or plugs in my opinion.

So will running both the caps and resistor plugs cause problems or charge the coils more ? I don’t know ! I think I need to call the NGK tech guy’s and ask

Anyway, I’ll try to call the NGK tech guy’s and get back on the resistance thing. Inquiring minds wanna know !

Keep your eyes and ears open and you'll learn something new, everyday.

[Whiskerfish]

Be interested in hearing what a Pro has to say.

Having read a fair amount about this over the years and done some actual study, yes some terminal resistance is necessary for spark shaping and to minimize "echo" (reflected signal going back up the line) or whatever you want to call it. The "Echo" is what causes the RFI. It is very basically a mini EMP as the spark stops. That is the Tick Tick Tick you hear in the radio. As the output of the coil falls to a point below that which is required to maintain the spark and the spark stops there is a surplus of energy sitting there. Terminal resistance can temper (absorb) some of that and minimize the RFI and up line signal reducing damage to the components that make and control the spark. As terminal resistance is increased it will also cause the spark to cut out earlier. That is where the tuning part comes in. Cutting out the spark earlier or later is part of the system balancing to control the amount of time the coil has to recharge. It is all a trade off. In our application of wasted spark design some terminal resistance is already built in with the second plug firing on an empty not charged cylinder. If everything else in the engine's operation was optimal I believe It would take specialized equipment to really determine the positive and negative effects when tuning the High Tension System and terminal resistance. In High School they only offered 3 electrical/ electronics classes. Once I completed those I did a Semester of independent Study playing with a couple of small tesla Coils and a high Voltage O Scope. I do not remember much of the specifics but I played with different frequencies of power supply and of course different voltages. Using the scope I was able to actually measure the output and compare that against the calculated output. My Calculations could get reasonably close but atmospheric changes from day to day were a big variable similar to varying charges of Gas and Air in a cylinder. But mostly it was just play LOL.

[redglbx]

Whiskerfish, great write up ! I did contact the NGK tech dept on this and am just waiting for them to reply back to me. So much of this I can no longer remember the details so I gotta ask the experts.

[millerdog]

Well let’s add abit to my snip attached above. The oe ignition coils were designed to properly charge/fill with the 5k ohm plug caps so if you eliminate them or use resistor plugs you need that5k ohm resistance to properly charge the coils which can be done with either the caps or plugs in my opinion.

So will running both the caps and resistor plugs cause problems or charge the coils more ? I don’t know ! I think I need to call the NGK tech guy’s and ask and-isn’t the answer here but I’ll add that I’ve been running the caps & resistor plugs fora long time w/o any noticeable negative effects which is odd because if those plug caps get over the stated 5k ohms you get all kinds of mysterious little miss’s and such, so you’d think increasing the resistance with plugs should do the same but I haven’t seen that but have had problems with slightly over 5k on the caps.

Also while we’re talking ignitions a huge misconception is that using the “hi” performance coils really boists the output across the board but actually it only gives you better power down in the low rpm’s and actually tapers off considerably with rpm. So why does that help in any way ? Well the main benefit is quicker starting and keeping the plugs cleaner & firing in. The low rpm ranges. Remember that our Keihin carbs are quite lean down low, below about 2200/2400 rpm about 15-15.5 to 1 a/f ratio (very hard to ignite) and then goes pig rich in the 10-10.5 to 1 a/f ratio, but higher rpms require almost no spark to ignite the mixture.

Anyway, I’ll try to call the NGK tech guy’s and get back on the resistance thing. Inquiring minds wanna know !

Interesting. I’ve got some non resistor plugs on the way. I’ll only have resistor wires then. We’ll see what happens.

[millerdog]

Whiskerfish, great write up ! I did contact the NGK tech dept on this and am just waiting for them to reply back to me. So much of this I can no longer remember the details so I gotta ask the experts.

Did you ever get a response?

[redglbx]

Whiskerfish, great write up ! I did contact the NGK tech dept on this and am just waiting for them to reply back to me. So much of this I can no longer remember the details so I gotta ask the experts.

Did you ever get a response?

Miller, still waiting on NGK to respond, probably won’t until at least Tuesday now, kind of surprised as in the past they’ve always been quick to get back to me. Anyway if they don’t get back Tuesday morning I’ll call them.