Spark plug wires

[rainbowshooter]

OK what is the deal with resitive spark plug caps besides they eliminate interferance? In the process of modifying the coils, put ditributor cap posts in so i can change the wires easier, and was wondering if regular plug wires for a car would work, or why they wouldn't.

[sixtysix]

Here is my theory, not supported by any known facts: I believe they will work. Regular car wires are resistive, but the caps are not. On bikes usually the wires are non-resistive and the caps are resistive. The whole deal with the resistance of plugs, wires and caps is confusing. I was told that they started making resistor plugs to eliminate radio interference. This makes sense, but most motorcycles do not have a radio. They do however have electronic ignitions and other electrical devices that may be affected by spark pulses. So I think one of the 3 things should be resistive (plugs, wires or caps) but not all 3. Racing engines use non-resistive wire, plugs and caps to allow maximum spark energy to hit the mixture. In reality though I have used resistor and non-resistor plugs interchangeably, with no difference in performance. I think the reason cars use the resistive wire cores is for flexibility, cost and manufacturing ease not for radio interference.

I think there is a tech tip showing regular plug wires on the old coils.

Read this it answers most of the questions about plug wires and how/why they are made the way they are.
Truth about ignition wires

This whole site has some good info on plug wires and effects of RF and EM interference in plug wires.

Magnecor Race Wires

[rainbowshooter]

Thanks a lot sixtysix. That was some pretty useful info.

[TopCatGr58]

Hey RainbowShooter,

I just noticed your location, in Tioga, Pa. !! Are you going to try to meet up with us at the XSEast2003 Rally being held in the Grand Canyon area this Memorial Day Weekend?? Lots of folks will be attending, and I'm sure plenty will bring tools and such and could possibly help you with your machine!?

In your test of your coils, I've got a pair that is testing bad on one side, but they say that the wires and such can go bad as well as the caps. Have you taken the caps of and inspected where it plugs into the wires, and then test the resistance of the caps and then the coils/wires without going thru the caps?? Might be a case of bad caps but good coils!? ALso the wires could be bad. I will be probably pulling the old wires out of my ?bad?coils to check the windings directly to be sure that the actual coil is bad and not just where the wires attach!!

Hope to see you at XSEast2003 since it's in your back yard!?
T.C.

[rainbowshooter]

My coils just recieved the modification but instead of putting a new wire in I put posts from an automobile distributor cap in. everything tests good on the coil, was just wondering if I needed to actually have the resistance. I am gonna try to get there I ask sixtysix for a shirt cause I just found out about the canyon, but I am waiting for a front master rebuild. Hopefully it will be here this week and I can get it on. Would love to make it, might even stop by without my bike to shoot the breeze for a few anyway.