kx80 weak spark need help

[choco711]

hey peeps my son has an 85' kx80 and the spark is as weak as piss it 's just enough to tingle my finger i've bought a new CDI and found that this was not the problem so then i worked my way back from the spark plug and i think that it's somthing to do with the stator but is it the coil the rectifier or both or is it the step up coil and i've just missed it so if anyone can help in any way shape or form it would be much appriciated.

[FilthyLuka]

silly question, you tried a new spark plug?

[F5 Dave]

They will appear weak at kicking speeds on some bikes but get fatter when running. old aircooled RM80 you can hardly see on kickover. Can't remember on KX, think was pretty dim.

But what is the problem, bike doesn't start or bike runs badly? Plug first even if does spark out of bike.

No regulator in system, the charge coil may need to be rewound if that is the problem, there is a pulsar coil I seem to remember on the KX is a external black cube, but if it is sparking then it will be working as that tells CDI when to fire.

[choco711]

that's how it seemed to be when it started to go months ago it was hard to start but once warmed up it would kick in and be ok but it became harder and harder to start until it needed to be run started to get it to go at all and then if it started it would run rough as guts for a couple of minutes and then come good and then one day it wouldn't start even when i ran started it. As i said before i've checked the spark plug and i got another cdi but I don't know how to test coils, I read somewhere that you shoul disconnect the coil and completly discharge the coil and then check and then check the resistance but i'm not sure if this is correct as i said anyhelp would be appreciated.
Oh by the way it's funny you should mention the old RM's because I have an 1980' RM 80 and that's what I was comparing it to but the spark from the RM jolts my arm up to my shoulder and as i said the KX only just tingles my finger.

[F5 Dave]

. . I read somewhere that you shoul disconnect the coil and completly discharge the coil and then check and then check the resistance but i'm not sure if this is correct as i said anyhelp would be appreciated. . .
That's hilarious, thanks, made me laugh.

Discharging the coil aside, Resistance checks are of limited value. They will only tell you if a coil is open or really shorted, but what tends to happen is the coil burns it's insulation & often only plays up under load.

Really the only option for the coil is if suspect then send to a competent coil rewinder, should find listing in local bike mags small adds.

But first I'd check that all your connections are good including one to ground & unplug kill switch for a test. Then I'd try a brand new plug, they often spark outside but die inside an engine. While you are about it try clean the carb small jets & check the reeds are not frayed or broken.

[choco711]

dddddd:wacko: