Spark Plugs

[Will]

HI Guys
This may be a stupid question, but what are the consciences of option which spark plug that work best in the EL. Mine has been converted over to 12volt and I tried Harley Plugs but they seem to foul quickly.

Thanks again
W

[Robert Luland]

HI Guys
This may be a stupid question, but what are the consciences of option which spark plug that work best in the EL. Mine has been converted over to 12volt and I tried Harley Plugs but they seem to foul quickly.

Thanks again
W

You system voltage doesn’t play into it. If not for judging? I’ve been running Bosch platinum’s for twenty years in my 60 pan. I’ve nicknamed them foul proof.

[knuckleheadtim]

If they are fouling with soot, you are probably running too rich. This could be caused by a bad float, mixture adjustment, or mismatch of parts in the carb. As you are riding down the road, soot will build up on the porcelain insulator, and the bike will begin to misfire, especially under a load.

If the plugs are oily wet, there may be a problem with the oil not returning from the cups in the heads.

[Rubone]

the consciences of option

Huh?

[T. Cotten]

Beware of modern productions of NGK A6 plugs.
Older productions (probably still available from Dixie) were great.
But suddenly they became resistors, and NGK denied it outright, even though the change was to accomodate newer Wisconsin motors.

Beware also,
that most modern pump fuels have deposit inhibitors that prevent conventional plug "reading".
Its either white or fouled. Sometimes both.

And face it,
if a motor must run rich, it is because it cannot run any leaner.
A simple bubbletest, as per http://virtualindian.org/11leaktest.html
may shine light on serious concerns.

...Cotten

[knu3]

Hi.
What does resistors mean?????????
Villy

[Chris Haynes]

Most modern spark plugs have a break, or gap, in the metal electrode inside of the porcelain insulator. This is the resistor. In the old days it was called pre gap.

[knu3]

Thanks Chris.
What influence does this resistore thing have??, i know people running theese
NGK plugs in the ol' Harleys...
Villy

[Rollo]

Spark plugs

I have been running D-16 Champion plugs for 35+ years and they seem to work fine. I run them in both my knuckles and my VL's. They are genrally available at most auto parts shops and if you are in the country they are usually at the local tractor parts places too. They may not be hot lick, fancy schmantzy plugs but they are readily available reasonably priced and seem to work just fine for me. If you need a little hotter plug then use D-14. I have occasionally had them crap out for no apparent reason so I carry an extra set just in case. Not sure if it is a quality control issue or what but it doesn't happen very often.

Rollo
AMCA #12766

[Will]

Thanks again for all the suggestions
W

[knuckleheadtim]

The purpose of the resistor is to cause the voltage to increase before jumping the plug gap. If you have a fouled plug, you can often get it to fire by pulling the plug wire back slightly away from the plug to accomplish the same thing. Since electrons have mass, they actually have momentum and tend to go in a straight direction.

It takes about 10,000 volts to ionize the gases in the plug gap, more under a load, and then about 2,000 volts to maintain current flow across the gap. If there is carbon on the porcelain insulator, the current will leak through it to ground, and the voltage will never get high enough to initiate a current flow across the gap. The waste spark (the plug not under compression) doesn't require nearly as much voltage.

Since resistors plug adds resistance to the circuit, it may not work well in a system that wasn't designed for them. Any resistance in the circuit will waste some of the electricity and shorten the duration of the spark. In the case of a Harley, it might work well to use a resistor plug for the cylinder running normal polarity if the reverse polarity plug is non resistor; I never tried it. Two extra resistances in the circuit would be a lot, and if you think about it, the waste spark plug probably acts much like a resistor gap.

A spark requires less voltage to jump to a hot conductor than a cold one, so the plug running reverse polarity is more likely to foul because the spark is jumping from the hot ground electrode to the cold center electrode. Sometimes switching the wires will get you out of a pinch by firing the fouled plug (didja hear about the fool who switched his plug wires so nobody would steal his Harley?).

[Sargehere]

I have been running D-16 Champion plugs for 35+ years and they seem to work fine. I run them in both my knuckles and my VL's. They are genrally available at most auto parts shops and if you are in the country they are usually at the local tractor parts places too. They may not be hot lick, fancy schmantzy plugs but they are readily available reasonably priced and seem to work just fine for me. If you need a little hotter plug then use D-14. I have occasionally had them crap out for no apparent reason so I carry an extra set just in case. Not sure if it is a quality control issue or what but it doesn't happen very often.

Rollo
AMCA #12766

Agree with you completely on the reliability and availability of Champion D16s (18mm "tractor plugs"), Rollo. Only one little detail: D16s are hotter than D14s.
Champion's Information ("411 on Sparkplugs")
http://www.championsparkplugs.com/sparkplug411.asp

and the website, right up front, says: "CHAMPION PLUGS GET HOTTER THE HIGHER THE NUMBER, COLDER THE LOWER THE NUMBER." D14s are more likely to foul at low speed running, or start hard, than D16s, the standard, hotter plug. Just a tiny correction, Rollo.

and Champion's "411" website is a source of spark plug education!
Technical spark plug information: sparkplug charts, cross reference numbers, iridium and platinum information...
It's chock full of good info on sparkplugs.
Note the "Ignition Anachronism">"wasted spark ignition," title, way down in the yella column on the left side of the page.
That refers to the secondary windings of wasted spark ignition coils (our Harleys) firing opposite charges, one positive, one negative, because the secondary (high tension) sparks don't both "come out" of the coil, but complete a DC loop, so the polarity at the electrodes is opposite: one is positive and one is negative, and explains how that can affect things like the life of the plugs individually, as one accretes metal on the electrode, and the other loses it, and mistakes that can be made by using iridium or palladium plugs in our bikes.

[RichO]

D-16's

I too have used D-16's for many, many, years in aSuper X, 101 Scout, and several knuckles. Any where an 18 mm plug was called for. You just have to gap them a little closer when used on the earlier mag fired machines. They now make a collar that makes them look just like the early knuckle HD plugs. I've ran original Hd knuckle plugs in my '40 for the last 10k and they work fine too. They're damn near bullet proof.

[Rollo]

spark plugs

Sarge,
Thanks for the correction. That was what I originally remembered but checked the HD knuckle manual and they go the opposite way. Thanks!

Rollo
AMCA # 12766