How do i know if my stator is bad?

Im having trouble with my bike getting spark.I have been through everything now im down to the stator and the cdi. First you should know that someone has added a headlight regulator to a factory stator. i took it apart and found the four screws that hold the coil to the mounting plate were loose. i thought this could be my problem. but nope still no spark. Could the stator be burnt out from someone adding a light regulator to it? any help would be appriciated.

bike is a 2004 yz250f

Do you know if it is the OEM stator? I'm not sure if you can modify a yz stator to run a light. If it is the OEM stator you can use an ohm meter to test it. The manual explains exactly how to do this. If you don't have a manual go to the FAQ page shown at the top of this section (wr/yz 250f) and download it.

Good Luck :smirk:

I beleive its OEM, it looks like someone has attached two wires on two different coils with some black goop. it does not look like something that yamaha would do. yes i have a manual i did not see how to do it but ill look again. i was pretty frustrated with it so i just stoped where i was with it and posted here on TT. thanks for the reply

check to see how much voltage is coming out of the stator with a peak voltage meter and check the resistance of the stator

I beleive its OEM, it looks like someone has attached two wires on two different coils with some black goop. it does not look like something that yamaha would do. yes i have a manual i did not see how to do it but ill look again. i was pretty frustrated with it so i just stoped where i was with it and posted here on TT. thanks for the reply

My 03 Manual shows this test procedure in Section 6, page 6-5. Section 6 also shows you how to test the other electrical componants for your bike.

Good Luck :smirk:

My 03 Manual shows this test procedure in Section 6, page 6-5. Section 6 also shows you how to test the other electrical componants for your bike.

Good Luck :smirk:

+1 Break out the multimeter and do what the book says.

ok i checked the stator, the left two wires meter out with in spec, the center pins are way out of wack, as well as the right two pins so im going to order a stator for it. i also checked my coil and it meters .4 spec is .08-.1 what does that mean for my coil? bad?

Look closely at the wires on the stator. You said the screws were loose. If they were loose enough for the coils to move around, they can touch the flywheel and some of the wires get cut or some of the coating rubbed off. If that happens, then the wires short against the flywheel when its on the bike. Look very closely to see if the wires look bright cooper colored, or if there are some turns that one or two turns of the wire are bare. That's all it take to short out. My experience, I had one do that, and it had been rewound with a light coil. They put one or two too many turns on it and it ran exactly 2 miles and quit. It was brand new, and they would not take it back or make it right.

it does not look like they rubbed at all but some of the copper is loose, i bought one on line. what about my coil metering at .4 the spec is .08-.1

Hi Bryan,

assuming that the ohmmeter was zeroed before testing,

If the high resistance spec. is 0.1, then at 0.4 ohms, the coil is out of spec. Often it's just a loose connection or corrosion in a connector that's the culprit (depending on where you're measuring the coil from).

If you can't find an obvious cause for the reading that's *not* the coil, then I'd replace it.

hey guys sorry i did not reply a while ago. i put a new stator on my bike and it started right up. thanks for all your help.

Glad to hear it! :banghead:

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