Removing sparkplug resistors?


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tom84std
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Removing sparkplug resistors?

Post by tom84std »



Several years ago I did this to my 1000. I later did it to my 1200. In trying to pin down a rough irregular idle problem I took apart my spark plug caps for inspection. I found the resistors to be quite deteriorated. Corroded, falling apart and the measured resistance all over the scale from one to another, no uniformity. In my mind, I saw no reason to add a resistor to a sparkplug which had a resistor already built in. I removed the resistors and cleaned the caps. I replaced the resistors with a short length of brass brazing rod about the same diameter and length as the original resistor. I removed the caps from the ends of the wires and cut about 3/8" from each wire and reinstalled the caps. This really seemed to help. It idled better and it seemed to run a bit smoother and stronger. Has anyone besides me had any experience in doing this?


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Re: Removing sparkplug resistors?

Post by WingAdmin »

Did you notice any increase in noise in your radio/intercom as a result?
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tom84std
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Re: Removing sparkplug resistors?

Post by tom84std »

Impossible for me to say since I use no intercom or audio but I have always wondered about that. What I didn't mention in my previous post was that the blue spark was visibly stronger, or it seemed to be. The main difference was the stronger idle. I actually had to lower the rpm a little. I'm told by people who seem to know that a little resistance is needed. I just feel that the one inside the plugs themselves is probably enough. I'm old enough to remember the old automobiles with solid wires and no resistors.
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Re: Removing sparkplug resistors?

Post by WingAdmin »

More than likely if you use the intercom/CB/radio, there will be a huge amount of noise in them now. If the spark is too hot, you may end up going through your plugs fairly quickly as well.
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Re: Removing sparkplug resistors?

Post by thrasherg »

As stated, I thought resistive caps were only meant to be used with non-resistive plugs, It is sure that removing the resistor will cause an increase in electrical noise, but if you are using resistive plugs it should not be an issue, the downside is if you put non-resistive plugs in without resistors in the caps, you will cause a lot of electrical noise and probably damage your ignition coils/CDI.. Most modern bikes do not have resistive caps as they all run resistive plugs, so I think you are doing the right thing as it will give you a stronger spark and the only downside is that you must ONLY fit resistive spark plugs..

Gary


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