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Chasing no spark

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Im working on an 87 YZ 125 which has no spark. Im having trouble figuring out exactly what is going on. I am getting voltage on the meter from the stator when I crank the engine and attach the meter leads to the brown stator wire on the connector and the ground. However, that is the only place im able to obtain voltage. So naturally I thought, ok the CDI is bad. I replaced it and still no spark. So I thought, ok its the ignition coil or plug wire -- Strike two. Still no spark. I also replaced the killswitch just to rule that out. No dice. What in the world could I be missing here? I cant seem to find any voltage coming out of the CDI. Ive tried to test every lead but nothing. I have the manual for the bike and I have attached the wiring diagram to this post (YZ125T). I have verified I have everything hooked up properly according to the diagram. Im at a loss here. Any ideas would be greatly appreciated!!!!

 

By the way, if anyone is interested, I have a spare CDI, ignition coil/plug wire, and kill switch for an 87 125 now!!! Apparently they work fine!! :)

Scan.jpg

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Not sure what you mean when you say you're getting "voltage" from th stator. When you properly test a stator you simply do a static test with an ohm meter, not a volt meter. To systematically test for no spark, the first test is to obtain the ohm spec from the service manual, then test, if it's good, then test the external ignition coil's primary and secondary resistance via ohm meter again, if that tests good, then the only component left that can be bad is the CDI (which can't be tested with an ohm meter) the CDI is now proven faulty by process of elimination of the other components .

Edited by Polar_Bus

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I was under impression it was AC voltage coming from the connector leading from the stator coil. If I place the red meter lead to brown on that connector and the black lead to ground, I get a voltage reading when cranking.

 

5vxb.jpg

Edited by ShsFunny

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How many  AC volts you are getting? You should have about 150 ohms across these two wires. Did you check them to ground also, should have no connection to ground. Also you should have about 100 across the pick up coil.

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How many  AC volts you are getting? You should have about 150 ohms across these two wires. Did you check them to ground also, should have no connection to ground. Also you should have about 100 across the pick up coil.

sound's like a job for RICKY STATOR to me!  :thumbsup:  :thumbsup: :thumbsup:  :thumbsup:  

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How many  AC volts you are getting? You should have about 150 ohms across these two wires. Did you check them to ground also, should have no connection to ground. Also you should have about 100 across the pick up coil.

 

 

It was very low...less than 10....Ill try and ohm it out tomorrow and let you know.......Jesus I hope I dont have to replace this stator.....just put my yz 400 in the shop for a complete head rebuild and I REALLY dont have the funds.

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...Jesus I hope I dont have to replace this stator.....just put my yz 400 in the shop for a complete head rebuild and I REALLY dont have the funds.

That's exactly why you need to be systematic when checking electrical components in the future. Most people "guess" and end up spending big money replacing perfectly good components. Checking a 2 stroke ign system is actually very easy, but you need the service manual. My #1 recommendation is if you bought a used bike, get a service manual, trust me it will eventually pay for itself two fold !

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That's what I do but unfortunately the clymer manual shows a completely different stator than the one on my bike. Not allot of info around on how to check this two coil type.

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This is the actual stator on my bike. What in the world should I be checking to see if it ohms out? Should I get an ohm reading by checking the top and bottom of each individual coil marked in the image?

 

qsnm.png

Edited by ShsFunny

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Is the photo you posted your stator or is the microfiche picture your stator?

 

 

Its the one thats actually on the bike.......Im beginning to see the light now that you mentioned that. My VIN on my bike actually corresponds to an 87 yz 125. The stator on my bike is from an 86. The stator for the 87 is this 

 

 

Screen_Shot_2013_10_03_at_8_26_48_PM.png

 

 

 

Someone frankensteined this bike apparently. Im surprised it ever worked. At any rate, I figured out how to properly test the resistance on the current stator and it reads over one and a half times the spec limit. The limit was 110 and it reads 398. Im hosed :(

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Its the one thats actually on the bike.......Im beginning to see the light now that you mentioned that. My VIN on my bike actually corresponds to an 87 yz 125. The stator on my bike is from an 86. The stator for the 87 is this 

 

 

Screen_Shot_2013_10_03_at_8_26_48_PM.png

 

 

 

Someone frankensteined this bike apparently. Im surprised it ever worked. At any rate, I figured out how to properly test the resistance on the current stator and it reads over one and a half times the spec limit. The limit was 110 and it reads 398. Im hosed :(

We have a stator for $99

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Yeah Ricky it looks like I'll be buying one from you....gotta support those that patronize the forums...everyone here has always helped me when I need it. It may be a bit though. Just spent 600 on a head rebuild for my yz 400

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