Topic: Spark plug caps

[schetebibber]

Hi all,

My sparksplugs 1 + 4 suddenly stopt sparking.
I measured the coil with an ohm-meter , it's +/- primair 5 and en secundair 16K, and that looks ok, the wires from and too the coils are ok, and i checked the pulses fom my Martek 440 ignition and that seems ok too.

I have NGK spark caps, and while i thought they should have a resistance of 5 K i measure nothing, like there is a broken connection inside.
But the strange thing is that this is not only on the 1 and 4 caps, but also on the 2 and 3 caps, and 2 and 3 are still functioning. 

Is this normal for sparkplug caps? Can these things be measured with an ohm-meter?


Greetings from the Netherlands.

[SteveD CB500F]

Eliminate the plug caps by swapping 1/4 with 2/3 - if the fault swaps then you need new plug caps. If not, try further up the ignition chain (eg coils - has the 12V wire dropped off?)

What does "schetebibber" mean?

[schetebibber]

Eliminate the plug caps by swapping 1/4 with 2/3 - if the fault swaps then you need new plug caps. If not, try further up the ignition chain (eg coils - has the 12V wire dropped off?)

What does "schetebibber" mean?

Hmmm.... why didn't i think of that? Thanks Steve!!

Schetebibber is an old Dutch word, difficult to translate, it's a combination of 2 words : "a fart" and "the shivers".
It might sound strange, but sometimes we call a loved one this way.

[TwoTired]

I have NGK spark caps, and while i thought they should have a resistance of 5 K i measure nothing, like there is a broken connection inside.
But the strange thing is that this is not only on the 1 and 4 caps, but also on the 2 and 3 caps, and 2 and 3 are still functioning. 

Is this normal for sparkplug caps? Can these things be measured with an ohm-meter?

You measure nothing? Do you mean 0 ohms or infinite, as in the meter doesn't move?  Assuming infinite, as in open, the plug caps are bad or you are measuring them wrong.  It seems odd that all four would die at the same time.  I'd take this as a sign to not do any gambling, you could lose your fortune.   

Swapping the caps may not be an option, because, at least on the 500/550, the 2&3 ones are longer than 1&4.  But, I don't know what bike you have.

Assuming they really are all open, they may have opened with different gaps.  The spark will jump a gap if it isn't too wide for the voltage applied.  Your ohmmeter is unlikely to apply enough voltage for gap jumping.  Maybe the ones on 1&4 have opened too wide for your ignition voltage?  In theory, if you reduced the spark plug gap, you might get the ignition to fire.  But, that's just a test, not a fix.

And, yes, these caps are normally measured with an ohmmeter beteen the spark plug and ignition wire contacts.
Cheers,

[schetebibber]

Does anyone know if the 5 K-ohm resistance in the sparkplug caps neccesary for the coils and my electronic ignition? Or is it only for eleminating radio interference?

Otherwise i'm thinking of drilling a hole inside-through the plug, soldering a solid cable from the plug-side to the cable-side and bypass all the spark blocking stuff.

[Philly550K1]

i would chase whatever is common to the two before messing with all of that (they're inexpensive to replace, anyway).  they began to fail at the same time? 

have you actually seen/verified spark on 2&3, or is it that those cylinders are firing but not 1&4?  i don't know martek ignitions -- how is the timing set?

and your meter -- is it digital, and do you select a range when measuring?  if the measurement is out of range, the meter may default to "schetebibber"..... 

what bike?  was it out in the rain before this problem?

-jc

[cb750_chris]

If you have a modern electronic ignition you need the 5k caps.  If you have an old points ignition go with good ol non resistor caps.  Either way make sure you use solid core wire and not the radio suppression auto wires.  You can get 6ft of solid core from Den Kirk for a few bucks.  I'm also bewildered by the no reading on the caps.  When caps go bad the resistance goes up.  NGK caps are really good.  I bet they are all fine. 

[eldar]

Oh I gotta know about this one! Can a person with points actually get away with using NON-resistor caps AND plugs? That would be a nice spark increase if it works.

[kghost]

Eldar, the answer is yes.

[Dennis]

Eldar, sure!
Why not? It was done that way on cars for years.
The resistance was added later when RFI became bothersome.
Copper wire, regular caps and non-resistor plugs were the standard on street rods for many years.

[schetebibber]

Ok, here is some more information. Thank you all for thinking with me.

2 weeks ago i tuned the ignition time with a stroboscope, and the engine was running fine.

I was driving on a hot summer day, no rain, moisture or other sorts of water. Suddenly the engine was going on half the power.
At the side of the road i discoverd that spark 1 and 4 was doing nothing.
I checked de pulses from the electronic ignition and they seem to be ok. i removed the coils and took them to my workplace.
the colis seem to be ok, 5Kohm at the primair, and 16Kohm at the secundair side.
I checked the plug caps and they all have an infinite resistance while they should be 5 kohm according what is marked on the side of the caps. Even if i put the range on my multimeter at 2 Mohm i measure infinite resistance.

To me it looks like there are gaps inside the plug caps, maybe because the resistors are blown up?
Comming days when i have more time i will do some more investigation.

[eldar]

There are not actually resistors in the caps. It is a type of metal that has a high resistance, I think that is how they work anyways.

SO 3 people say I can run with NO resistor plugs OR caps and that is ok?!

Hell that right there practically negates the need for hotter coils!

So does anyone know where to get caps like this?  Regular auto parts store?

[BobbyR]

I lost both 1&4 on a ride. the bike sounds awful but you can get it home. Since you have one discrete set of points for 1&4 and 2&3. I would check from the points to the plugs. My problem turned out to be a chafed primary wire. The nice part of your problem it is is limited to 2 cylinders. 

[cb750_chris]

Any old pre 80's honda caps are supposed to be non resistor.  I have tested several of them though and only 1 read 0.0 resistance.  As they get old carbon must build up in them some where but they are not servicable.  NGK non resistors don't have an 05 or 10 in the description code.  They just have 4 letters.   

[schetebibber]

Well,

I got me 4 new NKG spark caps, all of them measuring 5kohm between the cable and the spark connection. Connected to the coil i measure 5+5+16 = +/- 25 Kohm. So far so good.

The old caps must have some gaps inside them, maybe of damage resistors, or maybe just oldness, but these caps are small enough to keep functioning.

But unfortunatly, my ignition was still only on cilinder 2+3. I thought my Martek was ok, but I've discoverd that the 1-4 side of my Martek 440 is dead.
First i'm having a vacation, then i will think of what to do, i'm thinking of buying and re-installing mechanical ignition.

Ciao.

[Philly550K1]

thanks for the update, Fart Shake.    when you get back from vacation, there will be another whole discussion on electronic vs. points for you to read.  there are discussions on the topic, but i haven't seen a thread specifically on the merits of converting back to points.  i think you've discovered one such merit, which is, given that the stock coils don't fail much (or so i hear), you can at least tweak and clean the points to keep them functioning most of the time, whereas a failure in the electronics of a martek-type ignition, while apparently also rare, would be less responsive to the ministrations and supplications of the average home mechanic.  i don't know if you're SOL.  i'm curious.  that's why i'm here....

[Dennis]

Just a comment here.
Most of my bikes have points. I have one bike with a factory OEM electronic ignition, my '84 Yam RZ350. Anyone want to guess what is not running because of ignition problems?
Give me a nail file (or preferrably a points file), a matchbook and a screwdriver and I'll get a points ignition to spark. Can't say that for electronic!!

[schetebibber]

Here an update from my ignition problems.

After comming back from vacation i got the luminous idea ( luminous, is this a correct word? Sorry, english is not my 1st language) to place te "martek" rotor 180 degrees wrong, and switched the 12v wires to the coils. Started the bike and yes, now it was running on cilinder 1 and 4, and now 2 and 3 were dead, conclusion : 1/2 the Martek was dead. Testing with a light it seems to be ok, but with the coils it failed.
Since the "martek" electronics are all hidden in plastic, there was nothing else to do then throw it away.

After toshing and turning i decided to go again for an electronic ignition, after all the Martek must have been from the late 70's or early 80's, so it lived for about 25 years. A lot of maintenance for mechanical contact-points.
i bought me an "accent" electronic ignition, with magnetic sensors, comes with a replacement rotor with build in magnets.

Included my vacation the bike had stand still for about 2 months, it was great to have it running again.

By the way, i got me 2 as new second hand coils from a GL1000, they look exactly the same as the CB750 coils except for type numbers, they are different....   and i measured the primair coils, and they seem to be 3 ohm instead of the 5 ohm of my standard CB750 coils.
Is this indead the case? i'm wondering... 3 ohms or 5 ohms are hard to measure with my multi-meter...

Thanks all for your replies and thinking with me with my problem.