Yamaha Timberwolf 250 2x4 no spark - Yamaha ATV Forum
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post #1 of 3 Old 10-21-2018, 09:12 AM Thread Starter
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Join Date: Oct 2018
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Yamaha Timberwolf 250 2x4 no spark

Hi folks -- new to the forum, hoping for some help.

Trying to get ohms readings for the pickup and stator on my 94 timberwolf…..for the stator and the pickup coil.

Engine cranks fine, but no spark at the plug wire. I replaced the ignition coil thinking the primary coil was bad after measuring ohms with my tester.....

No joy.

I have pulled apart and cleaned the wiring connector stop switch/start switch assembly...went so far as to pull the wires out of the plastic blocks.....of course, two of the female connectors were old enough that the little tits that hold them into the block broke....sigh.....so they are connected outside the block for now. There was a good amount of mud inside the connector, so I was hopeful.

Still no joy.

So I have moved on to the pickup coil and stator.

The factory manual says the following :

To test the source coil (I assume this is stator)

Disconnect the CDI/Magneto coupler

Using the Yamaha pocket tester (set at Ohms x100) measure impedance between black (-) and brown (+) wires

428-523 Ohms at 68 degrees F is the spec

To test the pickup coil

Disconnect the CDI/Magneto coupler

Using the Yamaha pocket tester (set at Ohms x100) measure impedance between white/red (-) and white/green (+) wires

189-231 Ohms at 68 degrees F is the spec

So that is all well and good....but.....I am wondering if my Amprobe auto-ranging tester is giving me correct results given the experience with the ignition coil....I had found one ATV site where someone had a similar result...anything he tested with his tester was out of spec....after seeing it online, I can't imagine the "Yamaha pocket tester" is anything beyond a typical tester that has a "x100" setting...., and they are $150 new.....hoping I do not need to buy one of those just to troubleshoot this bike.....

I am getting .782 K Ohms for the stator and 980 K Ohms for the pickup coil.

If I remember my high school math correctly that is 782 Ohms for the stator (some 260 ohms above spec) and 2,000,000 ohms (and climbing) for the pickup coil.

And the weird thing is that if I leave the leads in place on the pickup coil, the number keeps climbing steadily.....over 2000 K Ohms after about 15 seconds.

My next step was gonna be replace the pickup coil since that is acting SO crazy....but like I said, given my earlier result with the ignition coil (the primary side was reading way high), not sure of my testing now. I cant believe that my igntion coil, staor AND pickup coil would all be bad at one time. It was fine when we parked it a year ago.

Any advice? Thanks all
shadango is offline  
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post #2 of 3 Old 10-21-2018, 12:23 PM
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Join Date: Feb 2015
Location: southern oregon
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here is my 2 cents. i struggle with the same issues using the meter and i have found that the number is not super critical as long as it is not reading open. it seams to vary from meter to meter, temp etc. you dont need the yamaha meter ohms are ohms. the stator is LIKELY ok and the reading is off due to temp or connections from the meter to the stator. was the test the same on all three wires in any combination. the pickup however is bad. you should have a steady reading again the exact number is not super critical but it should be stable. you will generally change the stator and pickup as a pair. depending on your budget i would recommend you call ricky stator and ask him for some help with interpreting the numbers. he walked me through a warrior i was having trouble with and even built me a custom stator to deal with a heat issue. he was very helpful and i was confident when i ordered the part it was going to fix my issue. the down side are his stators are expensive, they are worth it and will really last but if you call him for advice you are kinda obligated to buy a stator from him. if the machine is not worth the money or it is not in the budget i would feel about 80% sure it was the pickup (assuming you checked all the switches, grounds, fuses and wiring). if you go with one of the cheap brands like cal-trec make sure you install it right away. they have at least a 20% fail rate out of the box and only have a 2 week warranty. it is almost never the primary coil but that is realy old for a stator and pickup on a yamaha
cory52000 is offline  
post #3 of 3 Old 10-23-2018, 06:31 PM
Join Date: Sep 2018
Posts: 36
primary of ign coil should be about 0.5 ohms on any CDI system. you need an analog meter, much easier to use and no mistakes.
nothing wrong with your stator, your pickup is way off so must be bad
what is the number on the CDI?

Last edited by tom bauer; 10-23-2018 at 06:34 PM.
tom bauer is offline  

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