Spark Plug Cap Question
- Bambi
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Spark Plug Cap Question
15 Sep 2012 18:52
I have a 78 KZ 1000 A. When i changed my spark plugs the other day one of the caps was rather brittle and broke. I need to know what kind of cap to buy and how to replace it. I have never had issues with spark plug caps in the past so any information is appreciated.
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- MFolks
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Re: Spark Plug Cap Question
15 Sep 2012 19:00
The sparkplug caps unscrew from the sparkplug wires, and fail from age, heat & vibration.
These sparkplug caps contain a 5000 ohm, non servicable resistor. If you're changing one, do them all. Most Japanese motorcycle shop sell them at the parts counter. When preparing to reinstall them, first cut back about 1/4" of the sparkplug wire for a better connection, then screw the new ones on.
Never use resistive sparkplugs(the "R" in B8RES means resistor)with sparkplug caps containing built in resistors, as now you will have two resistances in the secondary circuit of the ignition coils, greatly weaking the spark energy.
These sparkplug caps contain a 5000 ohm, non servicable resistor. If you're changing one, do them all. Most Japanese motorcycle shop sell them at the parts counter. When preparing to reinstall them, first cut back about 1/4" of the sparkplug wire for a better connection, then screw the new ones on.
Never use resistive sparkplugs(the "R" in B8RES means resistor)with sparkplug caps containing built in resistors, as now you will have two resistances in the secondary circuit of the ignition coils, greatly weaking the spark energy.
1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
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- MFolks
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Re: Spark Plug Cap Question
15 Sep 2012 19:03
Still the original ignition coils? Read this:
Ignition Coils And Sparkplug Wire Choices
What came with the bike, were ignition coils that even when new were marginal, add years of cooking under the tank in the stop and go traffic, and the coils will probably fail when hot.
Replacement coils can be bought at www.z1enterprises.com I believe “Emgo” is the brand. They also carry the popular Dyna 2.2 and 3 ohm coils, along with replacement sparkplug wires.
Now, you have a choice on sparkplug wires:
1.Copper plug wires with no supression caps (the best choice, but will produce audio noise on Radio’s and TV’s). Not only do the copper core wires deliver better spark, they will also deliver a much longer lifespan - carbon core wires are prone to erratic spark delivery and early breakdown, & short lifespan.
2.Copper plug wires with supression caps(a built in 5000 ohm resistor, that can sometimes fail, like what came with the bike).
3.Copper plug wires with no supression caps, but using resistor plugs(the “R” in the plug number, like B8RES).
4.Supression plug wires with no supression caps.
Another choice is the Accel 3 ohm coils, with a similar, primary(small wire)electrical connection, using ring terminals as the Dyna ignition coils do. Whatever brand of coil you go with, make sure the primary wires will clear the mounting hardware, as the spacers come awfully close, possibly blowing a fuse. Some riders have replaced the metal spacers with non conductive Nylon spacers, reducing the chance of an electrical problem.
7mm sparkplug wires will fit the stock ignition coils(if they have replaceable wires, indicated by screw off caps on the coils with ridges). The sparkplug wires fit into a port with a brass ”Stinger” that goes into the sparkplug wire or lead(the Brit’s. Canadians, and other countries call the sparkplug wires (“High Tension Leads”).
Ignition Coils And Sparkplug Wire Choices
What came with the bike, were ignition coils that even when new were marginal, add years of cooking under the tank in the stop and go traffic, and the coils will probably fail when hot.
Replacement coils can be bought at www.z1enterprises.com I believe “Emgo” is the brand. They also carry the popular Dyna 2.2 and 3 ohm coils, along with replacement sparkplug wires.
Now, you have a choice on sparkplug wires:
1.Copper plug wires with no supression caps (the best choice, but will produce audio noise on Radio’s and TV’s). Not only do the copper core wires deliver better spark, they will also deliver a much longer lifespan - carbon core wires are prone to erratic spark delivery and early breakdown, & short lifespan.
2.Copper plug wires with supression caps(a built in 5000 ohm resistor, that can sometimes fail, like what came with the bike).
3.Copper plug wires with no supression caps, but using resistor plugs(the “R” in the plug number, like B8RES).
4.Supression plug wires with no supression caps.
Another choice is the Accel 3 ohm coils, with a similar, primary(small wire)electrical connection, using ring terminals as the Dyna ignition coils do. Whatever brand of coil you go with, make sure the primary wires will clear the mounting hardware, as the spacers come awfully close, possibly blowing a fuse. Some riders have replaced the metal spacers with non conductive Nylon spacers, reducing the chance of an electrical problem.
7mm sparkplug wires will fit the stock ignition coils(if they have replaceable wires, indicated by screw off caps on the coils with ridges). The sparkplug wires fit into a port with a brass ”Stinger” that goes into the sparkplug wire or lead(the Brit’s. Canadians, and other countries call the sparkplug wires (“High Tension Leads”).
1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
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- gumby prichard
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Re: Spark Plug Cap Question
15 Sep 2012 19:12MFolks wrote: (the "R" in B8RES means resistor).
i think you mean BR8ES
78 kz750 twin
77 yz125
91 cr250
99 dr650
ex's:
78 kz400 b1
89 yz80
99 klx300
77 yz125
91 cr250
99 dr650
ex's:
78 kz400 b1
89 yz80
99 klx300
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- bountyhunter
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Re: Spark Plug Cap Question
15 Sep 2012 21:29I'm dyslexic too, and it looked right until you pointed that out. :laugh:gumby prichard wrote:MFolks wrote: (the "R" in B8RES means resistor).
i think you mean BR8ES
1979 KZ-750 Twin
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- Patton
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Re: Spark Plug Cap Question
15 Sep 2012 21:52
Z1 Enterprises lists several varieties of spark plug caps.
Good Fortune!
Good Fortune!

1973 Z1
KZ900 LTD
KZ900 LTD
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- Bambi
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Re: Spark Plug Cap Question
16 Sep 2012 16:10
Thank you everyone who responded. Your advice was very helpful. I believe i will replace the coils and wires and all since i do not believe its ever been done in the 34 years the bike has been in existance.
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