Topic: Spark arcing from spark plug cap

[papi_sosaa]

These new caps never touched the old plugs. There is no grease on any of these parts.

[scottly]

I'm sorry, I can't offer any more than what I already have. Please let us know when you find a fix for your problem.

[papi_sosaa]

Just out of curiosity, why no dielectric grease?

It's a common practice to apply some to the sides of the spark plug cap/boot as it's non conductive and acts like an insulator, wouldn't that be a good thing?

[Deltarider]

I'm curious. This dielectric grease... (I don't even know the Dutch word for it). I have never heard of any mechanic here using it and personally I never needed it. What good is it and what are the no-no's?

[newday777]

No, there's no grease on the plugs or inside the caps at this moment.

Are you sure about that? The use of grease is a smoking gun for your quite unusual problem. I was wondering about it before, but since the problem then only involved the one cylinder I dismissed it. Now the problem has moved to two other cylinders, and the common denominator is the grease.

New plugs, new coils, new cords, new caps. No grease was applied yet and now, never will be.

Were the old coils and caps also from 4Into1?

[papi_sosaa]

No, there's no grease on the plugs or inside the caps at this moment.

Are you sure about that? The use of grease is a smoking gun for your quite unusual problem. I was wondering about it before, but since the problem then only involved the one cylinder I dismissed it. Now the problem has moved to two other cylinders, and the common denominator is the grease.

New plugs, new coils, new cords, new caps. No grease was applied yet and now, never will be.

Were the old coils and caps also from 4Into1?

So originally....

Caps, HT cords, and coils were OEM. Then I noticed the arcing on #4.

Cap #4 was broken and the rubber boots on either side of the #1 caps were cracking so I replaced caps #1 and #4 with resistor caps from Vintage750. Cap #4 was still arcing.

Now, I replaced all caps, HT cords, coils, and spark plugs (No grease!). Based off the condition of the electrode on the old spark plugs, the engine has been operating fine. Cap #4 looks fine but now #2 and #3 is arcing. I measured the Ohms of the caps and spark plugs and the range was between 4.7K Ohms to 5.3K Ohms.

When I have a chance, I'm going to take it all apart again, re-measure all my Ohms and then report back.

I'm curious. This dielectric grease... (I don't even know the Dutch word for it). I have never heard of any mechanic here using it and personally I never needed it. What good is it and what are the no-no's?

The point of the dielectric grease is to help keep water away from the spark plug. It's also supposed to make it easier to remove the cap from the spark plug. You're not supposed to put grease onto the spark plug terminal as the grease also acts as an insulator and can cause another set of issues. You're only supposed to apply a thin layer of grease to the cap boot so that it applies it to the ceramic section when you slot it onto the spark plug.

[MauiK3]

What about your engine block ground? Could it be affecting this?

[scottly]

Just out of curiosity, why no dielectric grease?

What is the dielectric (insulating) rating of the grease you used? The ignition system puts out thousands of volts.

[papi_sosaa]

What about your engine block ground? Could it be affecting this?

In this situation, no.

Just out of curiosity, why no dielectric grease?

What is the dielectric (insulating) rating of the grease you used? The ignition system puts out thousands of volts.

Not sure what its rating is but the primary purpose of dielectric grease is to prevent moisture and corrosion from reaching the electrical contact(s) that it is protecting. Dielectric means insulating or non-conductivity. It's supposed to prevent arcing without interfering with electrical current if applied correctly.

One of the biggest uses of dielectric grease is for spark plugs.

I have a suspicion that I might not be screwing these HT cords in as far as I think I am and it could be causing extra resistance that is leading to the arcing. The broken OEM cap was one thing but this is obviously something else that is a symptom to that fault. This is why I'm going to measure the HT cords and caps separately and then measure them once they're connected.

I think I'm also going to put the OEM coils back in. I don't like how the contacts in the coils from 4into1 also screw into the HT cords like the caps do. The OEM coils have like a nail or spike that the HT cord just presses onto.

[Don R]

 It sounds like plenty of spark is getting to the plug, it's enough to overcome the plug caps somehow. I wish I was close, I'd love to see it myself.

[scottly]

Are the 4into1 caps NGK brand?

[papi_sosaa]

Are the 4into1 caps NGK brand?

No, they're some Chinese knockoffs. I believe the NGK resistor caps are discontinued.

[Don R]

 When the plug caps go on, can you feel the threads on the sparks plug engage the springy latch in the inside of the caps?

[papi_sosaa]

When the plug caps go on, can you feel the threads on the sparks plug engage the springy latch in the inside of the caps?

Yeah it feels pretty solid going on. Even taking them off takes a bit of force.

[scottly]

What was the brand of the grease?

[papi_sosaa]

Permatex Dielectric Grease.
https://www.amazon.ca/Permatex-22066-Dielectric-Tune-up-Grease/dp/B07NQP339F?th=1

[dave500]

ngk resistor caps are still available.

[bryanj]

If you can find them Dave, apparently NGK have stopped making them

[dave500]

I see lots available here in Australia from many places,I guess until stocks last?

[MauiK3]

Something doesn't add up. Good caps, wires, coils and yet spark still gets out. Maybe something in the wire itself? Has to be a "leak point" somewhere.

[papi_sosaa]

Been busy the last two days but I'll have time tomorrow to test everything.

I checked the store page on 4into1 for the caps again and I just noticed that they actually do not recommend using resistor caps with resistor plugs.
https://4into1.com/set-of-4-spark-plug-resistor-covers-honda-cb650-gl1100-gl1200/

There is this forum post from 10 years ago where they quoted Hondaman from 15 years ago lol
http://forums.sohc4.net/index.php?topic=147184.0

Basically, you shouldn't use both. Either buy a non-resistor cap or modify a resistor cap and remove the resistor. Then, use a resistor plug as they'll last longer than a non-resistor plug. This also opens you up to the world of stronger spark iridium plugs as they're resistor only plugs.

Word of the day: Resistor

EDIT:
I had a moment to quickly measure the OEM coils on my bench:
Coils = both coils primary circuits are approximately 2.3 Ohms
Coils = both coils secondary circuits are approximately 12K Ohms
Caps = approximately 5K Ohms
Plugs = approximately 5K Ohms

Looking at 22-22.5K Ohms per coil bank. This doesn't factor in if the coil wire is installed correctly.

[scottly]

The original problem started on the #4 cylinder, that you blamed on the chipped cap. The chip that far from the threaded end of the plug should not have had any effect, as the inside of the cap is normally insulated, as well as the porcelain on the spark plug. You then replaced the 1&4 caps with the new caps, and the problem persisted on #4, before changing the spark plug. The only thing that stands out is the grease, which is somehow conducting the spark down the side of the plug or the cap or both, and isn't needed anyway.
The resistance isn't the problem, and the manual shows resistance caps for the Canadian models. Weren't the original caps resistor caps?

[papi_sosaa]

The original problem started on the #4 cylinder, that you blamed on the chipped cap. The chip that far from the threaded end of the plug should not have had any effect, as the inside of the cap is normally insulated, as well as the porcelain on the spark plug. You then replace the 1&4 caps with the new caps, and the problem persisted on #4, before changing the spark plug. The only thing that stands out is the grease, which is somehow conducting the spark down the side of the plug or the cap or both, and isn't needed anyway.
The resistance isn't the problem, and the manual shows resistance caps for the Canadian models. Weren't the original caps resistor caps?

Again, everything currently on the bike is brand new; caps, coils, cords, and plugs. There is no grease ANYWHERE in the system and it's currently arcing on #2 and #3.

Give me a minute to go measure the coils and we'll see what the total resistance is.

EDIT:
Coil 1-4 (CAP-WIRE-COIL-WIRE-CAP): 24.2K Ohms
Coil 2-3 (CAP-WIRE-COIL-WIRE-CAP): 24.9K Ohms
I'll have to pop the spark plugs out to get the full circuit end to end but when I measured them before install, they were reading between 4.7K Ohms to 5.3K Ohms.

[scottly]

I'm just saying that the only thing that can explain the original problem is the addition of the grease.

[papi_sosaa]

I'm just saying that the only thing that can explain the original problem is the addition of the grease.

The problem is still happening without grease, it just moved plugs.

The grease is not the problem.