KX Riders
Maintenance & Technical => KX500 Original => Topic started by: kiwikx500 on April 30, 2006, 10:54:04 PM
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Mines a 1990 would anyone know what size out of the two mine is meant to be,i want to ohms test it.Whats the resistors actual purpose ? Does it weaken the spark if it goes ? Cheers 8-)
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In most cases they increase their resistance if they are going bad. ohm test yours and that will tell what you have. The resistors help cut down on RF's. Is your plug cap the factory cap? I will test mine tonight.
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Cheers,Yep mine the original cap.What does RF stand for please ?
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Radio Frequency. To test the plug cap it needs to be unscrewed from the high tension lead. You will need some kind of multi meter like a fluke meter to test the cap. You measure from one end to the other of the cap. My Clymer manual doesn't offer a spec. but NGK only offers 5k or a 10k.
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I find it a complete pain in the ass to check the cap. Best best is to remove the cap and check the spark from the line to the cylinder without the cap. Then install the cap with a plug and see if you get the same spark from the plug. I've RARELY seen a bad cap. Doesn't happen often, but they are cheap to replace.
Good luck
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Yep. less than 3.00 dollars from dennsikirk.com
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I'm a little confused about what Gowen said....I can't remember when's the last time I saw a 10K resistor cap on any machine.
Just about everything takes a 5k ohm cap. I just unscrew the cap from the coil wire and check resistance with an ohm meter. I usualy get 4 to 5 k ohm on a good cap. I've tried getting spark from the bare coil wire which works but even a "going bad resistor cap" can produce a spark with sparkplug installed and grounded on the motor.
It might just end up being too weak for the motor to run properly.
What i'm trying to say is it's impossible to measure peak voltage and resistance by just seeing a spark jump from the wire to the motor. Anybody with me on this ??
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Yes, You will need a peak reading volt meter to check voltage coming from the stator to the cdi box and then to the coil. Rapair.com has adapters that plug into multi meters that allows them to read peak voltages. I have never seen and enigne with 10k resistor I agree most are 5k.
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I guess I'm slack. I've always used a spark to judge the ignition. It doesn't take much of a spark to run a KX. I ran with a weak spark for years. I guess I missed the question as I am dodging from this site and work at the same time. Resistors are there just to reduce electrical noise from the coil/wire/plug from interfering with the CDI. I've never really pushed the issue, as I don't have a stock ignition system. It has no resistor. My previous ignition system had one. And like all, they are 5k. There is no performance loss with using a resistor I don't believe. I could be wrong.
As for my comments on caps. If you suspect a cap, replace it. Half the time your cap is going to read 0 like mine and like my old stock one.
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Gowen they are for elec. noise. In some cases when it fails it increases it's resistance which will effect the voltage going to the plug. It seems that the 89 and newer 500's ran a plug with a resistor in the plug. My 87 factory plug doesn't have a resistor but the plug cap itself is the resistor. I can dig up more info when I get home.
My plug is b8eg
89 and new 500's run a br8 the R stands for resistor. I have a ngk book at home I'll check and see.
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?
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Also keep in mind that you don't need a resistor cap AND a resistor plug (although I think that is what I have - I better check). The resistor is for RF (radio frequency) suppression. the RF will give audible electrical noise if you ride with a MP3 player, walkman or communicator. It might also affect the picture quality from a helmet cam but I'm not 100% sure on that. You would think it would boost the spark to have no resistor, but in practise the plug lead often has so much resistance that it makes little difference. Cam.
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Ohm my plug cap and it was 5.0k ohms. But I don't run a resistor plug.
Gowen ohm the cap that was with the system you gave me and the cap was 2.0 ohms. No resistor. Thay why the 89 or new 500's came with a BR8EG and my old bike came with a B8EG. Just like cam dais as long as we got a resistor some where plug or plug cap then we jammin :mrgreen:
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They still cheap here in the big schemes of things but $23 US here in New Zealand must because they are so heavy to ship here (8 times the price lol even though prob same distance from japan lolol) Am i hearing right ? I can run my 1990 500 with a cap with no resistor if i choose and do absolutely no damage ? I called into a lawnmower shop and was going to fit a briggs and stratton (no laughing) cap - they are good in that you can physically see and attache the HT lead way better for positve confirmation of excellent contact - but the lawnmower men said about the resistor and did not think it was a good idea ? Cheers 8-)
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Kiw,
You will be fine with an aftermarket plug cap. If you don't ride with music or do laps around your house no resistor is required. I believe it may be an FCC requirment to have a resistor cap when they import the bikes. I put a non-resistor cap on my sons bike since the aftermarket one sealed better (against mud) than the stocker. Cam.