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Discussion Starter #21
You're making progress. Tickling kill switch simulates trigger causing spark. If trigger wiring is ok you likely have defective CDI. I think your trigger is integrated into stator. You claim no spark with previous stator and coil secondary fires plug which proves ability to fire secondary. I'm fairly confident CDI is culprit. Post part number on module here on forum if possible. Will try to help
Here is part number 54839031700
 

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Dirt Wizard
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Multi meter using ktm specs for coil primary and secondary yes i have peak power adapter im getting 130 volts from cdi to coil blu/whi wire
Usually you check primary coil voltage across the coil.
Cdi could fail from bad stator I do believe. Not sure if bad cdi would fail a new stator. (I suppose any severe load in an ignition system would fry other components)
If stator is starting to fail this early in the picture, there might be a problem with the flywheel.
I have no knowledge of an accurate testing procedure on a cdi without bench testing it.

I would be willing to learn if someone does have a procedure.
 

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Usually you check primary coil voltage across the coil.
Cdi could fail from bad stator I do believe. Not sure if bad cdi would fail a new stator. (I suppose any severe load in an ignition system would fry other components)
If stator is starting to fail this early in the picture, there might be a problem with the flywheel.
I have no knowledge of an accurate testing procedure on a cdi without bench testing it.

I would be willing to learn if someone does have a procedure.
We have had 2 same/similar bikes all the way from 65 racing. The only testing of CDI's we have ever done is to swap the CDI for the one from the other bike. In 12 years of racing we have only had one CDI die on us.
 

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Discussion Starter #26
We have had 2 same/similar bikes all the way from 65 racing. The only testing of CDI's we have ever done is to swap the CDI for the one from the other bike. In 12 years of racing we have only had one CDI die on us.
Im pretty sure its stator or flywheel leaning toward stator ordered a oem i tried cdi off my 200 exc still no spark
 

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Here the correct CDI's for a 08 bike (based on these numbers I assume your bike is a 250xc-w):

Your CDI: 54839031100

2007/2008 bikes:
300 xc-w: 54839331200
250 xc-w: 54839031700
200 xc-w: 52339031900
250xc: 54839031600
250sx: 54839031800

2005/2006:
250 xc-w: 54839031400

2004 bikes have an older type of CDI that does not fit your bike.

Your motor number should start with 548 (same start number as the CDI). Based on the CDI number you have given us your bike is a 250xc-w. But it looks like your CDI has been superseeded. I am not convinced this is your issue. But once you start grasping straws (like we are doing now) perhaps the next step is to fit the correct CDI and hope for the best...

Here the CDI you need:
Cdi Unit 250 Exc 07/08 54839031700 $ 189.01 They are still available.
 

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Im pretty sure its stator or flywheel leaning toward stator ordered a oem i tried cdi off my 200 exc still no spark
Yep, that is a good way of testing. Just fit the CDI and keep the plug out to test. (Do not try to start motor as the spark timing might be all wrong!)
 

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Im pretty sure its stator or flywheel leaning toward stator ordered a oem i tried cdi off my 200 exc still no spark
The KTM stators have always been one of their Achilles heals! We started travelling with a spare new stator as we had some bad experiences. That then lead to us having 2 bikes so I would have time to do repairs at the track if needed while my son used the 2'nd bike.
 

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Discussion Starter #30
Yep, that is a good way of testing. Just fit the CDI and keep the plug out to test. (Do not try to start motor as the spark timing might be all wrong!)
Yea that's what i did still no spark same voltage as the other cdi was putting out also 130 volts oem stator with broken wire has 6 volts more than the new Chinese stator my new stator is oem be here Thursday hopefully that will be the problem
 

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Dirt Wizard
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We have had 2 same/similar bikes all the way from 65 racing. The only testing of CDI's we have ever done is to swap the CDI for the one from the other bike. In 12 years of racing we have only had one CDI die on us.
Yep, same way I use to test the sems ignition systems. Just swap out with known good one.

Lee87, good luck with new stator. Hopefully that fixes your problem.
I have never got an decent ignition components from china.
Last thing I bought off the off chance was a couple R1 voltage regs as they were $20 compared to $250 genuine. Bought 2 thinking I should surely get one good one. Both we're putting out 15.5-16v. Would've fried the new battery.
 
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Discussion Starter #32
Yep, same way I use to test the sems ignition systems. Just swap out with known good one.

Lee87, good luck with new stator. Hopefully that fixes your problem.
I have never got an decent ignition components from china.
Last thing I bought off the off chance was a couple R1 voltage regs as they were $20 compared to $250 genuine. Bought 2 thinking I should surely get one good one. Both we're putting out 15.5-16v. Would've fried the new battery.
Yea its hit or miss with that stuff ill let you know how i goes when stator gets here
 

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Hi Guys,

I have a 2010 250 xcw that I am also having a spark issue with. I have gotten the stator rewound as I was sure this was the problem. Since then I have swopped out the ignition coil with a other 250's one as well as the CDI. All with no spark. Funny thing is I am testing 15.5 Ohms on the plug which is correct. I cleaned all earthing wires to make sure it is earthing correctly. I have it with a local mechanic now who is trying to solve the problem but so far he also hasn't had any luck.

If anybody knows what it might be please give me a shout.
 

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Wish I had the answer... We have only had 2 stroke SX KTM's. Their stator is simple and only has one winding (for the spark) the XC, XC-W etc have up to 3 windings on the stator. ( Ignition/spark, battery charging, lights).

Make sure you have the right winding connected to the right circuit!
Disconnect all but the spark/ignition supply from the stator. If you still have no spark the issue is in:
  • The stator
  • The connectors
  • The wiring
  • The coil
  • The spark plug cap
  • The spark plug
  • The CDI (In 12 years of racing MX we have had only one CDI die on us...)
And that is it...
 

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Hi guys,


Wanted to share a great site for cross-referencing KTM parts. It can cut down on lots of research. Just plug in the part number in the search box and it will show you all the bikes that share the same parts. Sometimes is crazy to see how many bikes one part fits! https://www.ktmonlineparts.com.au/part/ktm/54839031700#content

Also, just wanted to share a story about lost spark and and the epiphany working on my Honda 400EX back in high school. I had stripped down my quad to powder coat the frame. Got it back and put back together, but it only ran for around 3-5 minutes and shut off. No lights, no spark, no neutral green light, nothing. Wait around 5 minutes and everything was back to normal, but when I started it again, the same thing happened. Stumped as could be. One day I was just going around touching stuff and I moved the exhaust and saw a spark from the bolt going to the frame, then AH HA! that's when I realized the stator was generating power but it was not a complete circuit because after powder coating the frame, I removed the ground for the motor. I ran a cable from the engine mount to bare metal and BAM, all is good! Was so proud of myself :)

My last no spark issue on the 2000 KTM 250EXC was a bad CDI box. I had a small crack in from the forks hitting it from a fall. Luckily I was riding local when it lost spark!
 

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Discussion Starter #36
Well i still have not figured out why im not getting spark new stator new cdi tested cdi harness and coil coilwire plug cap could it be flywheel i can still bump the motor around with start button when i let off of it if its close to the pickup it will fire but not while cranking any ideas
 

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Discussion Starter #37
Yep, same way I use to test the sems ignition systems. Just swap out with known good one.

Lee87, good luck with new stator. Hopefully that fixes your problem.
I have never got an decent ignition components from china.
Last thing I bought off the off chance was a couple R1 voltage regs as they were $20 compared to $250 genuine. Bought 2 thinking I should surely get one good one. Both we're putting out 15.5-16v. Would've fried the new battery.
Still no spark after changing and checking every but flywheel any idea
 

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Dirt Wizard
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Still no spark after changing and checking every but flywheel any idea
Mate, I'm only clutching at straws, rarely have I had a faulty flywheel, but it can happen. The flywheel hasn't sheared the key way has it?
Do you guys have people over there who bench run stuff? If I have a brain teaser, I send the whole ignition system to Steve at betta bikes over here and he bench tests it and can pin point the issue before I start throwing hundreds of dollars at sh-t. Granted it costs 100 to a $150, but can save you more than that and the headache.
The only other way I have done it is as axzon mentioned and that's swapping bits out with a known working one.
 
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Discussion Starter #39
Mate, I'm only clutching at straws, rarely have I had a faulty flywheel, but it can happen. The flywheel hasn't sheared the key way has it?
Do you guys have people over there who bench run stuff? If I have a brain teaser, I send the whole ignition system to Steve at betta bikes over here and he bench tests it and can pin point the issue before I start throwing hundreds of dollars at sh-t. Granted it costs 100 to a $150, but can save you more than that and the headache.
The only other way I have done it is as axzon mentioned and that's swapping bits out with a known working one.
I found another thing wrong with bike i put my ground lead on battery and other on engine had positive voltage got to checking around found fried voltage regulator dumpi g positive voltage to all my grounds all of the grounds were going positive when i hit start button soon as i let if off they go back to ground and i would get a spark if crank was in position at least i hope that's it
 

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Discussion Starter #40
Has anyone seen a voltage regulator short out and kill all grounds with positive volt while engine is cranking starter button pushed i have positive voltage on motor and frame soon as i let off the start button they go back to ground and ill get a spark when pick up coil is in position
 
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