Originally Posted by Queen of Spades
Have multimeter and manual opened to section on testing ignition coil. Manual provides values for two resistance tests - blue/white to ground, and blue/white to plug wire.
At the top of the ignition coil test section the manual says that I need to "disconnect all wires" before using the ohmmeter to test for the given values.
The specified values KTM provides are
primary coil: blue/white – ground 0,425 – 0,575 Ω
secondary coil: blue/white – ignition wire 10,80 – 16,20 kΩ
Below the table of values, the manual then says
"Before checking the ignition system check..." and goes on to list whether the ignition is on, the kill switch is on, the neutral light is on, motorcycle can be started with clutch in and that the battery is charged.
What is confusing to me is the seeming incongruence between the introductory paragraph, and the second paragraph. From reading other sites, resistance testing should be done with no voltage present. Is the KTM manual saying the same thing, but to first make sure these other things are OK -- before disconnecting everything?
Assuming I should have the battery disconnected, I'm showing "1. " on the multimeter readout on both tests, using the battery NEG as ground. If I tough the leads together I'm showing ~0.00. The MM is set to Ohms at 20k (the lowest value).
The book is telling you to check the easy stuff first. Should also ask is there gas in the tank and is the fuel petcock on.
To resistance test the coil, it has to be disconnected.
But if the bike is running OK, and you're making these checks than it probably won't show what the issue is.
I was suggesting that you make sure the coil is getting voltage. That would be the wires to the coil and should be 12volts.
But again, any checks really need to be made when the bike won't run.
So for me, the first thing I would do is wait til it stalls out again and can't be restarted, then verify if you are getting spark. You can do this several ways: pull the cap and let the plug hole rest against the motor. Crank and look for a spark (don't touch the cap while cranking unless you like 10,000 volt zaps)
Also pull the plug and re-install in the cap. Ground the plug against the motor (again don't touch while cranking) and verify spark.
If you're getting spark then the intermittent problem may have gone away while you were unhooking things, or it may not be a spark problem at all. (pain in the ass intermittent electrical issues)
BTW, 20k ohms shouldn't be the lowest setting, usually there's a 200 ohms setting, though I don't know anything about your multi-meter.
BTWBTW, I'm not convinced it's an electrical issue. A fuelling issue can shut the bike down immediately. When people think of fuel issues, they thing of running out of gas where the bowl steadily leans out, you get some sputters as fuel sloshes and gets sucked up then none then sucked up. But, like what someone said earlier about a pebble in the float bowl, if something cuts fuel to the jets immediately, clogs it immediately, there will be no sputtering. It will shut off just immediately like you've cut the ignition, especially on a thumper.