Cdi or coil

I checked all the readings from the stator to cdi and they are all in spec, now when i have the spark plug cap off the wire and put wire on the cylinder it makes a little spark. Tried many caps and many old and brand new plugs and no spark. Could it be the cdi or coil? 2001 yz 250 2t.
 
I would do an OHMS test on the coil. Most of the time the issue is one of these....
A. Your ground and coil mounts are dirty or rusty. Remove the coil and clean all the connections and mounts with sand paper.
B. The connection between the plug cap and the plug wire is loose or rusted or corroded. You can unscrew the plug cap off the wire and cut about 1/4" off the wire and then reinstall the plug cap.
If the primary side of the coil has a low OHMS reading it will not create the needed spark
Paw Paw
 
I would do an OHMS test on the coil. Most of the time the issue is one of these....
A. Your ground and coil mounts are dirty or rusty. Remove the coil and clean all the connections and mounts with sand paper.
B. The connection between the plug cap and the plug wire is loose or rusted or corroded. You can unscrew the plug cap off the wire and cut about 1/4" off the wire and then reinstall the plug cap.
If the primary side of the coil has a low OHMS reading it will not create the needed spark
Paw Paw

Did that. The coil is supposed to read 0.2-0.3 ohms and when i tested it it read 0.4 and 0.6. I sanded the post and stuff and did the plug cap thing.
 

SRAD97750

Moderator
Staff member
I checked all the readings from the stator to cdi and they are all in spec, now when i have the spark plug cap off the wire and put wire on the cylinder it makes a little spark. Tried many caps and many old and brand new plugs and no spark. Could it be the cdi or coil? 2001 yz 250 2t.
What is the issue?
What have you done recently?
Did it run recently?
Start from the beginning. -BIG DAN:thumb:

EDIT: For general troubleshooting, CDIs and Coils are good 99.9% of the time, when the connections are good. I have only heard rumors of them failing, so I don't actually believe it happens.
 
What is the issue?
What have you done recently?
Did it run recently?
Start from the beginning. -BIG DAN:thumb:

EDIT: For general troubleshooting, CDIs and Coils are good 99.9% of the time, when the connections are good. I have only heard rumors of them failing, so I don't actually believe it happens.

Riding around all of a sudden just died, thought it was plug, changed, still dident start. Gas was on. Checked for spark with a few BRAND NEW plug, nothin. Checkes stator ohm readings, all where in spec. Tried changing plug cap, still nothing. Cleaned connections on ignition, nothing. Checked primary ignition reading (should be 0.2-0.3) and got a reading of 0.4. Checked secondary ignitiot and thats in spec too. When i have no plug cap or plug in it the bare wires do spark. Something is weak somewhere and im thinking its the ignition.
 

SRAD97750

Moderator
Staff member
Excellent.
When i have no plug cap or plug in it the bare wires do spark.
How many times does it spark? Just once initially, or continuously weak?
The CDI on some models will allow a single weak spark in the kill position.
I am not worried about the 0.4 reading. it's very close and would still spark.

How about the kill switch? Should have continuity to ground in the kill position. Should be 'open' when set to Run.
I'm sure I'll think of something else.
-BIG DAN:thumb:
 
Excellent.

How many times does it spark? Just once initially, or continuously weak?
The CDI on some models will allow a single weak spark in the kill position.
I am not worried about the 0.4 reading. it's very close and would still spark.

How about the kill switch? Should have continuity to ground in the kill position. Should be 'open' when set to Run.
I'm sure I'll think of something else.
-BIG DAN:thumb:

There is no kill switch. Checked that too. It continously sparks and looks strong but i have never seen spark before unless it was with the gap of the plug because ive never had this problem
 
For about $4 you can replace the plug cap. I would do that and see if it works first. All your specs sound reasonable.
Did you check fuel flow?
Compression?
 
For about $4 you can replace the plug cap. I would do that and see if it works first. All your specs sound reasonable.
Did you check fuel flow?
Compression?

Theres no problem with fuel flow or compression. The problem is there is no spark for the bike to start with
 
Will do. I looked at stator just with the left side cover off and the stator looks kinda rusted but if i pull it off do i gotta worry about any wires or parts shooting off or anything?


Nah. You should be good. Clean upe the stater a little bit and see what happens.
 
IMAG0080.jpg
 
Just a thought, shavings on the crank positioning sensor will cause it to not fire as its not getting the signal to fire the spark plug, Learned that recently with my bike. :banghead:
 
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