Race this weekend and NO SPARK!! I’ve tried EVERYTHING KX250f

lukelona11
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8
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11/11/2020
Location
Gloucester Point, VA US
Hello guys and gals. I am in a very big bind here and have resorted to posting a thread about my issue bc I have surfed web for weeks and can’t find my issue.

2013 kx250f. Backtrack about 2 mo, bike running great after rebuild (10-20hrs) suddenly bogs n cuts off on track. Got it to start again after several attempts. Quit within 10 min.

NO SPARK. I have tried the following...
•replace stator with new one, no fix.
•swapped coil with known good coil. No fix.
•swapped condenser/capacitor with known good. No fix
•swapped regulator/rectifier. no fix.
•replaced ECU with brand new OEM part. No fix.
•unplugged kill switch. No fix.

STILL NO SPARK! I have a race this weekend and have 3 days to figure this out. Can anyone tell me what else I could check? Maybe I’m missing something? Is there anything else that controls spark?

For the record, this happened during practice of my last race. So I lost almost $1000 in expenses that weekend and now I’m borderline gonna not make my last race of season this weekend. I’m beyond frustrated. Please any help is appreciated as I’m out of ideas here. Thanks y’all
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Shaggin589
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Gallatin, TN US
11/11/2020 8:21am
I recently had a buddy who’s Yamaha did almost the same exact thing. I checked it all for him and it turned out the culprit was water/dirt in some of the plug connections under the tank. My advice would be to unplug and clean every plug on the harness. It costs nothing but a can of electrical contact cleaner and some time. After I did that the bike fired right up and he hasn’t had an issue since.
mx317
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11/11/2020 8:26am Edited Date/Time 11/11/2020 8:27am
Tip over switch? Spark plug I'm sure you replaced.

1
11/11/2020 8:28am
Did you swap wire and boot with the coil? Continuity test your wiring. Maybe a broken wire or bar wire shorting? Check/clean all your grounds too
1
lukelona11
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Gloucester Point, VA US
11/11/2020 8:31am
mx317 wrote:
Tip over switch? Spark plug I'm sure you replaced.

I’ve swapped plug yes. Tip over switch I have done the “rattle test” to make sure it’s not sticking. I’m not sure how to OHM it out exactly. But I also thought that in the event the top over switch fails, it causes the bike to shut off after few seconds of running.
This bike doesn’t start at all. I will test it if anyone knows the procedure

The Shop

lukelona11
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Gloucester Point, VA US
11/11/2020 8:34am
Did you swap wire and boot with the coil? Continuity test your wiring. Maybe a broken wire or bar wire shorting? Check/clean all your grounds too
I swapped my whole coil. I’ve also removed the boot and checked right from the plug wire and still nothing.

I have removed and retightened ground by ignition coil. This is the only frame ground I can find.

I started doing wire testing but the harness is so complex you’d have to dissect it completely I think to be able to do any real testing. By this I mean take all of the tape and coating off of harness to access each wire. Correct? Or is there a better way?
kb228
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Mansfield, OH US
11/11/2020 9:17am
Did you swap wire and boot with the coil? Continuity test your wiring. Maybe a broken wire or bar wire shorting? Check/clean all your grounds too
lukelona11 wrote:
I swapped my whole coil. I’ve also removed the boot and checked right from the plug wire and still nothing. I have removed and retightened ground...
I swapped my whole coil. I’ve also removed the boot and checked right from the plug wire and still nothing.

I have removed and retightened ground by ignition coil. This is the only frame ground I can find.

I started doing wire testing but the harness is so complex you’d have to dissect it completely I think to be able to do any real testing. By this I mean take all of the tape and coating off of harness to access each wire. Correct? Or is there a better way?
Look at the schematic in the service manual and make sure you have continuity to the start and end of each terminal. Or replace the harness.
1
Paw Paw
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Benton, LA US
11/11/2020 9:56am
Ohm test the coil and also check the kill switch.
Have you looked to be sure you don't have spark?
Are you sure it's not a fuel delivery issue or timing issue?

Paw Paw
1
lukelona11
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Gloucester Point, VA US
11/11/2020 10:14am Edited Date/Time 11/11/2020 10:14am
kb228 wrote:
Look at the schematic in the service manual and make sure you have continuity to the start and end of each terminal. Or replace the harness.
Meaning the terminal of one plug on one end and where ever it leads to check that same wire right?
I’ll download the manual and see if it shows it that well.
lukelona11
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Gloucester Point, VA US
11/11/2020 10:16am
Paw Paw wrote:
Ohm test the coil and also check the kill switch. Have you looked to be sure you don't have spark? Are you sure it's not a...
Ohm test the coil and also check the kill switch.
Have you looked to be sure you don't have spark?
Are you sure it's not a fuel delivery issue or timing issue?

Paw Paw
I’ve swapped the coil with brand new known good coil. Kill switch is new, but I have tried unplugging it also.

100% sure it’s not fuel or timing. I’ve done these rebuilds several times and know them very well. I don’t usually get stumped, but this has me ready to pull my hair out

100% does not have spark. Confirmed by grounding plug to frame and using spark tester.
lukelona11
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Gloucester Point, VA US
11/11/2020 10:18am
Is there any other sensors that control spark if they were to fail?

AFAIK the only ones that would affect spark is
•coil
•stator
•ECU
•kill switch
•possibly reg/rec?

Is that it? If so I guess I’ll have to pull and dissect entire harness ?
lukelona11
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Location
Gloucester Point, VA US
11/11/2020 10:22am
Also, forgot to add.

I have ran my FI light and I get the steady flash indicating “no fault”
Weird thing is you’d think if there was a broken or shorted wire within the harness, the FI light would pick it up. 🤷🏻‍♂️
526
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Colgate, WI US
11/13/2020 4:43am
I had a Suzuki do the same thing and it was the spark plug
walent215
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Ridgecrest, CA US
11/13/2020 8:22am
As mentioned unplug each connection and spray them with contact cleaner. Sounds like a wire harness to me.
I have also heard of magnetos going “ bad” .
Seems unlikely but with everything else you’ve tested and that sounds like the only thing left.
Good luck bud, I hope you find it quick and make your race!
11/13/2020 11:42am
I’ve had an 12 rmz flywheel go bad and a 16 kx450f do the same thing
mxtech1
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Galesburg, IL US
11/13/2020 12:57pm
sheared flywheel key?
mx317
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TN US
11/13/2020 1:18pm
mxtech1 wrote:
sheared flywheel key?
Wouldn't it still fire, but be out of time?
captmoto
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Rancho Cucamonga, CA US
11/14/2020 9:18am
mxtech1 wrote:
sheared flywheel key?
mx317 wrote:
Wouldn't it still fire, but be out of time?
Yes.
jtses0026
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Hanoverton, OH US
4/20/2024 6:00am

Did you ever figure out what it was? I'm in the same position with my 2014 kx250f

27thmx
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Naples, FL US
4/21/2024 4:25pm

Check grounds and ground connection, clean all connections, new plug…

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