resistor plugs AND resistor caps?

[wirespokes]

I've tended to stay away from resistor spark plugs and used the 5K ohm NGK plug caps on any bikes with electronics.

However, Guzziology recommends using both resistor plugs and resistor caps.

Have you found this necessary? Is anything bad likely to happen if I run only 5K ohm caps and non resistor plugs on a 99 Bassa?

[bigbikerrick]

I have run non resistor plugs on my 98 EV, with no ill effects.  It  had no change in fuel economy, or throttle response. This bike has always run well, and one time ,for the heck of it, I  also put on some of the metal plug caps that come stock on a 76 Convert, and it still ran fine with those.  I was just testing those, to see if they would arc out or anything, as I thought about using them on my 73 Eldo, just for nostalgic looks.
Rick.

[guzzisteve]

I have only run one or the other, usually caps but not both. On my 98EV I run the caps not plugs. I also don't use NGK plugs but Champions N7YC

[Tom H]

My EVT calls for resistor caps and plugs. I always thought it should be one or the other, but that's what my bike is supposed to have.

Tom

[Antietam Classic Cycle]

I have only run one or the other, usually caps but not both. On my 98EV I run the caps not plugs.

This ^^. Had been using NGKs but after too many faulty ones have switched to Denso.

[wirespokes]

Thanks, guys! I guess I'll keep doing what I've always done.

That's interesting, Charlie - I haven't had an NGK fail in decades. However, the non resistor plugs are getting harder to find. I'll have to look into the Densos. Thanks for the tip.

That does bring up another question. NGK plug caps. Now that NGK no longer makes them, what's the next comparable product? Anything as good or better?

[Antietam Classic Cycle]

That's interesting, Charlie - I haven't had an NGK fail in decades. However, the non resistor plugs are getting harder to find. I'll have to look into the Densos. Thanks for the tip.

I hadn't either until recently. NGK BP6ES equivalent is the Denso W20EP-U, BP7ES equivalent is W22EP-U.

[aklawok]

Overall resistor plugs/caps have little or no benefits to the machine equipped. They are to prevent harmful RF( radio frequency interference) to sensitive equipment around you. As a licensed amateur radio operator, there are many things that cause this, but I can tell you that since resistor systems are required equipment, just be courteous to those you may be unaware of the noise you may be generateing.

[Tom H]

Charlie,

Wonder if you got some of the knock offs. Read that they are popular brand to knock off.

Tom

[Antietam Classic Cycle]

Charlie,

Wonder if you got some of the knock offs. Read that they are popular brand to knock off.

Tom

Purchased from the local NAPA. All characteristics were as described on NGKs website about how to identify genuine NGK plugs.

[Tom H]

Sounds like you got the real ones. Sorry you got a bad batch or three, Always had good luck with them.

Yom

[sign216]

The only time I run non-resistor plugs is on vintage equipment.  Does it matter?  It did once.

I was resurrecting a '69 Benelli 350 single (badged as a Wards Riverside).  It had the original pink Magneti Marinelli plug, so I replaced it w a fancy new Bosch plug, with a precious metal fine wire electrode. 
No spark. 
I put the 50 yr old orig. plug back in, ... and spark!

Turns out the modern Bosch plug, in addition to being a resistor, had a larger gap.  The long gap + resistor was too much for the Benelli's electrical system to overcome.  I eventually got a modern non-resistor plug, closed the gap to the original Benelli specs, and that worked fine.

Joe

[aklawok]

Points ignition systems are not conducive to a high voltage output. The Advent of CDI and later HEI systems made spark way more efficient and powerful, but require some extra resistance to muffle spurious RF.
In ye olde days of tuning, there were oscilloscope ignition diagnostics machines on every corner garage, in these you would be able to look at the wave form of the spark and see a square block when the system was working properly or rounded with squiggles if not. Clean, sharp ignitions were the goal.

[wirespokes]

I used to think that any resistance in the high tension side wasn't needed and unnecessary. I ran my non-electronics bike with no resistor cap or plugs. Then an electronics guru informed me that some resistance at the end of the line actually aids the high voltage transmission. So I went with 1K ohm caps for the non-electronics bike.

He also said that running with no resistance can damage the coils, and with electronics - the ICU. Evidently it's a slow degrade so not noticeable.

Ever since, I've run 1K with points and 5K with electronic ignitions.

[aklawok]

Think of the resistance like a cork in a bottle, when the resistance is overcome you get sort of a pop ( but not really) it does not improve the spark as much as how the spark gets made.

[wirespokes]

I know enough about electricity and electronics to know that even simple circuits have a lot more going on than the simple explanations provide. A high voltage line develops a force field around it and that changes the flow characteristics. I believe there's more going on than a resistor cap letting the charge build up before being overcome and jumping through it. That's what a spark plug does, after all.

No, I believe something more complex is happening. Plus, who knows - maybe the resistor cap also blocks a return flow back to the coil? I guess you can see a lot with an oscilloscope, but that's not me - I'm no electronics expert.

[aklawok]

Resistance in the plug/cap and wire dampen the "force field" ( the source of harmful RF) that is created and then collapsed by the coil over and over again each spark cycle .

[wirespokes]

I know this is an old thread, but thought I'd add another data point.

A friend has had a lot of trouble getting his resurrected (30 years?) T3 running right. It would run pretty good sometimes, and then it would be rough. He kept fooling with the carbs, changed plug leads, caps, was thinking of changing coils, wanted to ultrasonic the carbs again, revisit the points...

He was running NGKs, resistor plugs even though I cautioned against them. He knew better and figured it wouldn't make any difference.

After a while I told him to get some Densos and he thought I was nuts. Wouldn't listen to me. He was getting more and more depressed. One day I told him it was cheaper than replacing coils or the other things he was planning. I guess that made sense to him, so he got some.

Well what do you know? With the new Densos the bike is running best it ever has - smooth and powerful. He's flipped out. He can't believe bad plugs were the cause of those unusual symptoms. Like they say, 90% of carb problems are electrical.