Spark plug cap resistor results??

[Rob_02gs500]

Hey so i found a few threads and topics about removing the resistor in the cap but didnt find any one posting long term results.
Anybody got any? thinking about doing it just to see how it works.

[adidasguy]

By the picture shown, it appears the linger caps with the 45* angle have resistors.
The newer ones with the 90* angle do not appear long enough to have a resistor.

I have some of each in the Bike Cave. I will examine both tonight.

There was another thread about running larger wire to the coils and adding an extra ground to them. Makes sense. That 3' of wire from the ICU to the coils is pathetically small size. Firing side of coils is grounded through the frame. Direct ground back to battery might improve things.

[Rob_02gs500]

Hmmm...interesting. I took out the resistor on the OEM Denso spark plug caps and took pictures of the plug firing without and then installed it back and took another pic. There is a noticeable difference in the size of spark produced when firing with no resistor. Im going to replace the resistor with bare copper grounding wire and see what happens. Going to test my radio in my car along side of it running. I dont see why a resistor in the cap and plug are necessary.

[adidasguy]

Opened them up. There is a cylinder resistor. Resistance is 11k ohms.
It is some special ceramic material. hard to cut. I did break one in half and now infinite resistance. I suspect the silver end caps are part of making it work.

Anyway - that means you can't cut them to reduce the resistance.

Not a scam - many RFI items are made from exotic materials to eliminate RF interference. So not surprising that breaking it broke it.

I'll see this weekend when I do a wrenching day what happens with a brass slug in there in place of the resistor. My concern is that the reduced resistance may put more load on the ICU - shortening its life. Or shorten the life of the coils due to increased current flow. Or shorten life of plugs due to higher current and bigger spark.

Its OK to try. If I break a bike or fry an ICU or coil, I have spares.

Remember that 11k ohms is a pretty big resistor. Without it, hard to say what will happen.

[adidasguy]

Food for thought.
We can run without resistor plugs and things are just fine.

Here are some readings:

Spark plug cap: 11k ohms

NGK non-resistor plug: close to zero resistance.
NGK Resistor plug: 5k ohms
NGK Iridium plug: 4.7 ohms
Brisk plug: 7.5k ohms

So it might seem that due to extra resistance in the Brisk, to eliminate the problem one person had: remove  the resistor from the plug caps  and the spark will be stronger. The Brisk plug has more path for the spark so a slightly higher available current/voltage should be beneficial for the person with an issue, which I believe is fouling. That would mean a higher voltage is necessary for them to work. If the battery drops voltage, the spark voltage also goes down. Therefore a dip in voltage would cause starting issues due to the current required for the starter motor which would drop the voltage.

When that person put new NGK plugs in and the bike worked, that would be due to less plug resistance and no fouling. I'd love to buy that set of plugs from that person and run tests.

I am in contact with Brisk regarding that persons problem. I have the many GS500's and equipment to run tests and determine what could have gone wrong. Possibly the newer ICU's are more efficient and/or the coils have a higher spark voltage. That might be why they do not cross reference their plugs for GS500's before 2004. We know the bikes are the same but the ICU is different.

DISCLAIMER: I tested only ONE new plug of each type. Industry standards allow 10% variance. Often for non-critical parts a 20% variance plus or minus is allowed for a part to pass manufacturing tests. A better test would be to sample 5 or 10 plugs from different manufacturing batches.

Given the higher resistance in the Brisk and that we can run with non-resistor plugs, I feel confident to run tests on the bike with the resistor removed from the plug cap.

[Rob_02gs500]

Ah. I got interested in the Brisk plug thread which got me to the thread about the resistor caps.  My caps were no where near 11k ohms when i tested them, more like ~6 and the other was ~9. I would think if anything that the spark plug may wear out sooner than one that has the resistor like you pointed out but a recommend change is around 7000 miles correct? They should be able to last that many miles. Which now i am convinced that the plug cap is a maintenance item as the resistor gets older it breaks down and increases resistance to beyond spec. I couldn't find anything on what the resistance should be. 11k is a big difference between what i got on mine.

So you are saying run the resistor in the plug cap and then run resistor-less plugs?

[adidasguy]

I am making no suggestions as I am not versed enough in spark plugs to do that.  I am noting observations to provide information in this thread.

I will test more caps and see if there is much variation between newer and older caps.

[Rob_02gs500]

Ah. Okay. I removed the resistor in my stock Denso cap and replaced it with some #8 copper wire from Home Depot. Runs great and don't noticed any inference in my car radio with the GS running next to it. Gonna try that for a while and see how it does.

I was just going off your statement that we can run without resistor plugs and things are fine so it sounded like you would keep the resistor in the cap...