CDI help needed - crackling noise

[ako]

One of my other bikes, a KTM 640 has a crackling noise from the back near the battery when the ignition is turned on.

I used my stethoscope to work out it is the CDI crackling. It sounds like a little man is in there with a 12v arc welder.

Would the logical assumption be the CDI has broken components or bad solder joint inside?

Or could it be a bad connection in the loom that needs cleaning.

Or could it be something up the line like a faulty regulator/rectifier giving silly voltages.

Have only just found the problem tonight, could do some multimeter checks but don't know where to start yet. ???

Any advice from an electrics guru would be appreciated as I am not one......

 

[ako]

I have been told it won't be the rect/reg since the noise comes as soon as the key is in 'on' position.

I swapped the CDI for another unit and it made the same noise. I cleaned all the terminals with contact cleaner.

Can anyone give me a clue as to what I need to check? Any ideas would be greatly appreciated.

 

[crazypj]

Does it do the same when engine is running?
Could be the timer is switching on and off (although it's solid state, the voltage spikes could be burning something internal?)
What make is it? (Nippon Denso, Bosche, etc)

 

[ako]

Thanks for the response Crazypj.

It is a Kokusan CDI. I haven't checked the noise when the engine is running, wasn't sure if I was going to fry something.

I will hook up a fuel supply and try starting it.

 

[ako]

I measures 13.4V across the battery terminals with the ignition off.

With the ignition on, it dropped to 12.8V. I thought this is ok, but not an expert. No headlights or other loads were switched on.

I have drained the carb bowl, and got fresh fuel lined up on my test tank. Will try to start tomorrow as the kids are in bed, and I like my a-hole in the un-torn configuration.

 

[crazypj]

Check for damp or corrosion in the block connector. (wiring harness side)
Not sure if it has the mini pin type? (same size as computer connectors)

 

[ako]

Got home late from work so no engine starting tonight .

I have already cleaned the connectors with contact cleaner. They are old school pin type, like molex.

I might roll up some sand paper and give them a one on one clean.

 

[crazypj]

Try pulling on individual wires where they are crimped onto connector, could be a loose one. (don't go nuts, just enough to see if anything is loose)
Contact cleaner doesn't do much (if anything) to remove corrosion

 

[ako]

Started it tonight. Bike seemed to run and rev ok. Checked the spark (with plug out and arcing to block) and it was big and fat.

The noise was stick there when the bike was running, but with the sound of the exhaust I could only hear it with stethoscope on.

Holding the engine kill button also stopped the noise, the same as the key does.

Will put the kids to bed, and then spend the rest of the night cleaning terminals......