Spark Plug Caps

[fbody_mike]

I recently found a bad resistor plug cap on my 85 gs550e. I was able to rebuild it temporarily by taking a cracked one and taking it guts and putting it in the other one. I got 4 new NGK ones coming in the mail since I figure if one went bad, the others are probably in the same condition.
Anyhow, I have taken a few of these apart in my time and have always noticed that the resistor pellet is always chalky white. This bad one was grey and had no continuity. The copper screw piece was also a little lose so I think it was arcing in the cap itself and basically cooked the resistor pellet. Anyone notice that chalky white is good and grey black is bad?

 

[Redman]

Nope. Never took one apart.
What i have noticed is that a good one is about 5K ohms, and stays that way for long time, years and years, then startes to go higher resistance, say 7.5k then 10k then infinite/open resistance (no continuity as you say).
I knbow they are 4 or 5 bucks each, so, yah, replace all of them.
Also know that most any mo'cycle parts suppliuier carries the NKG, dont need to be zuki dealer.

 

[Gorminrider]

I recently found a bad resistor plug cap on my 85 gs550e. I was able to rebuild it temporarily by taking a cracked one and taking it guts and putting it in the other one. I got 4 new NGK ones coming in the mail since I figure if one went bad, the others are probably in the same condition.
Anyhow, I have taken a few of these apart in my time and have always noticed that the resistor pellet is always chalky white. This bad one was grey and had no continuity. The copper screw piece was also a little lose so I think it was arcing in the cap itself and basically cooked the resistor pellet. Anyone notice that chalky white is good and grey black is bad?

Hmmm- that's an interesting observation. I wonder if they can be seen to be degrading as somewhere between "chalky white" and "grey black"? like a tinge of greyness? I am wondering why it burned too, of course or Is there a known lifetime for these?

 

[tom203]

Humidity ,especially in storage , will cause this. But caps are cheep,