2004 KTM125sx, intermittent spark

davis224
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davis224
Edited Date/Time 1/26/2012 7:01pm
Hasn't been ridden since 2006, but back then it stopped kickstarting, and it would only bump start. Ran fine once it was going, just would not kickstart. I dug it out recently and looked at it today and found it sparks only every so often. I think I've narrowed it down to the CDI, bad wiring connections (i was told by a former KTM tech this was a problem KTM had noted before), and something with my flywheel (had a small amout of rust/corrosion but not near the actual magnets). I'm not the greatest with electrical so I could use a little help. The stator seemed like it was putting out fine. If I had to put my money on something right now I'd say it was the CDI, I cracked it in a crash early in 2006, but ran fine after that so I never replaced it, but moisture may have gotten into it. I don't want to blindly replace it on a hunch though if its something else.
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motofab36
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motofab36 4/22/2010 6:15am
4/22/2010 6:15am
Aaron I would bet it's the cdi. I have seen them do weird things, I've even seen a couple over the years on utility quads (witch is unfortunately what i work on most) that had no spark or intermitant spark and you could give them a good wack with a wrench and the would work.

Have you checked to see what years that cdi will work on?
Nutty C
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Nutty C 4/22/2010 11:10am
4/22/2010 11:10am Edited Date/Time 4/22/2010 11:13am
I would say stator. Unplug the stator and check with a ohmn meter to ground. A cooked coil will conduct to ground. As I recall you will have a low and a high speed coil and I am guessing your low is cooked.
xnationalwrench 4/22/2010 5:29pm
4/22/2010 5:29pm
davis224 wrote:
Hasn't been ridden since 2006, but back then it stopped kickstarting, and it would only bump start. Ran fine once it was going, just would not...
Hasn't been ridden since 2006, but back then it stopped kickstarting, and it would only bump start. Ran fine once it was going, just would not kickstart. I dug it out recently and looked at it today and found it sparks only every so often. I think I've narrowed it down to the CDI, bad wiring connections (i was told by a former KTM tech this was a problem KTM had noted before), and something with my flywheel (had a small amout of rust/corrosion but not near the actual magnets). I'm not the greatest with electrical so I could use a little help. The stator seemed like it was putting out fine. If I had to put my money on something right now I'd say it was the CDI, I cracked it in a crash early in 2006, but ran fine after that so I never replaced it, but moisture may have gotten into it. I don't want to blindly replace it on a hunch though if its something else.
If the CDI is cracked chances are thats the bad part.
davis224
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davis224 4/22/2010 9:25pm
4/22/2010 9:25pm
Nutty C wrote:
I would say stator. Unplug the stator and check with a ohmn meter to ground. A cooked coil will conduct to ground. As I recall you...
I would say stator. Unplug the stator and check with a ohmn meter to ground. A cooked coil will conduct to ground. As I recall you will have a low and a high speed coil and I am guessing your low is cooked.
Stator output and resistance was good.

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R-acer
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R-acer 4/23/2010 4:14am
4/23/2010 4:14am
Just helped a friend out with his CR250. It would just stop sparking at random.
In this case, it turned out being a bad conection from the wires going to the coil.
partialperson
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partialperson 4/25/2010 8:03am
4/25/2010 8:03am
Electrical crap like this can drive you bananas! Had a brand spankin' new '99 YZ80 that would miss, cutout at random. Always when it was important in a race. This went on for like three months until one day I'd had enough while it was doing it on the stand. I fisted the kill switch and it reved to the moon. I also had a dragbike that would cutout halftrack for no apparent reason, had a 2step, stutter box, ended up the chassis was twisted just right at halftrack to pull a wire and rubbed a bare spot on a wire. I have good stories about mice and teething dogs also.
TERIYAKI
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TERIYAKI 4/26/2010 2:46pm
4/26/2010 2:46pm
R-acer wrote:
Just helped a friend out with his CR250. It would just stop sparking at random. In this case, it turned out being a bad conection from...
Just helped a friend out with his CR250. It would just stop sparking at random.
In this case, it turned out being a bad conection from the wires going to the coil.
Had a similar problem on a KTM 144 last year. The ground for the coil that is attached to the frame was broke and sometimes made connection. Remove the tank and check the wires on the coil.
davis224
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davis224 4/27/2010 5:11am
4/27/2010 5:11am
R-acer wrote:
Just helped a friend out with his CR250. It would just stop sparking at random. In this case, it turned out being a bad conection from...
Just helped a friend out with his CR250. It would just stop sparking at random.
In this case, it turned out being a bad conection from the wires going to the coil.
TERIYAKI wrote:
Had a similar problem on a KTM 144 last year. The ground for the coil that is attached to the frame was broke and sometimes made...
Had a similar problem on a KTM 144 last year. The ground for the coil that is attached to the frame was broke and sometimes made connection. Remove the tank and check the wires on the coil.
I've already taken it all apart and cleaned all connections, my coworker who used to work at a KTM dealership said he'd seen that problem a lot, and what they did was hardwired the stator wires together, getting rid of the connector. The connector was causing too much resistance, not allowing the flow to pass it easily. I'll try that first, then go from there.
Cygnus
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Cygnus 4/28/2010 5:36am
4/28/2010 5:36am
POS KTM! Scrap it.Laughing

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