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Need some spark plug boot help


Guest Thainglo

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Guest Thainglo

All - had a cylinder (#4) that wasn't getting any spark, after getting good tests at the TCI for ignition and pickup coils, I thought the culprit might be the spark plug wire/boot. I pulled the retaining screw out of the boot and cleaned it, the spring, and the thrust plate. The 10k resistor measures 9.3k, within 10% tolerance.

 

What's troubling me is I am not getting any connection between the pin on one end of the boot that slides into the spark plug wire and the retaining screw. Even when I strip all the pieces out and probe deep into the boot to make a connection with the pin, no luck. Thinking to test my theory of a bad boot out on another boot, I stripped one that I knew was good. Once again, no connection between the retaining screw and the pin.

 

Does this make sense? Also, as I reassemble the boot, I believe the parts go in:

1) spring

2) thrust washer

3) resistor

4) screw

 

Appreciate any help - thanks!

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Guest Thainglo

Wiring is checking out good when I remove it from both the coil and the spark plug boot. No breaks. I'm scratching my head on why I can't get connectivity across the both ends of the boot. :think:

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How long has it been since a complete tune up was done on the bike? I dont know how long you have had it, but the 1st thing I do when I get a bike, 'specially if it's used, is a full tune up. Another thing I do whenI put the wires on a 1st gen is take a small pick and inset it into the wire end that goes into the coil as it will help it center itself on the pin.

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Guest Thainglo

Squidley - owned the bike a couple of weeks. Bought it to put back together. Its getting new plugs, plus a complete carb tear down and rebuild. Any ideas on how I could be reading an open circuit from one of the boot to the other?

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Squidley - owned the bike a couple of weeks. Bought it to put back together. Its getting new plugs, plus a complete carb tear down and rebuild. Any ideas on how I could be reading an open circuit from one of the boot to the other?

 

 

Are you reading through the plug boot to the open end of the wire where it pushes into the coil? The boots are a resistor type and I know that in their age they can corrode up and cause all kinds of problems. For about $40 you can replace all of the wires and boots and not have to worry about anything....just a thought

:2cents:

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Guest Thainglo

Are you reading through the plug boot to the open end of the wire where it pushes into the coil? The boots are a resistor type and I know that in their age they can corrode up and cause all kinds of problems. For about $40 you can replace all of the wires and boots and not have to worry about anything....just a thought

:2cents:

 

Replacing all the caps and wires might be the next step. Are there any preferred sources out there?

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Guest Thainglo

Has anyone used a standard universal kit from Accel or MSD? I was going to head over to the walmart and pick up a set of 7mm RFI wires and caps.

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You should have conductivity through the boot, from the screw on the top to the plug terminal on the bottom. You should register the 10k or so from the resistor. Strange that you don't read conductivity on a boot that fires. Corrosion is the only thing I can think of. Sometimes there can be a gap in a cap or wire and the spark will jump it and still fire the plug. This is demonstrated by pulling the cap from a running engine. The spark will jump from the cap to the plug and fire the cylinder up to some distance before the engine starts missing.

 

Jeremy

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Guest Thainglo
You should have conductivity through the boot, from the screw on the top to the plug terminal on the bottom. You should register the 10k or so from the resistor. Strange that you don't read conductivity on a boot that fires. Corrosion is the only thing I can think of. Sometimes there can be a gap in a cap or wire and the spark will jump it and still fire the plug. This is demonstrated by pulling the cap from a running engine. The spark will jump from the cap to the plug and fire the cylinder up to some distance before the engine starts missing.

 

Jeremy

 

The lack of connectivity when the plug fired fine is what I can't figure out. The resistor tested out fine at 9.8k Ohms. I'm flummoxed (how often do you get to use a word treasued by Dr. Suess?!) :rotfl:

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