1989 yz 125 with no spark

[kevinfries]

Well im trying to fix my friends 89 yz125, it has no spark. The coil has been replaced along with the CID and spark plug. I checked the grounds and they are fine, well 1 wasnt, so i grounded it, but still no luck. When i was testing the stator on my cr125, the manual gave me specs for the resistance between the wires. If anyone knows those it would be VERY helpful. Or if you have any other suggestions, thanks.

 

[reelrazor]

Just check for continuity to ground on the stator leads. There should be NO continuty to ground through either wire.

Wire to wire, well, there should be resistance, but not a hell of a lot. Main thing to check is whether it varies if you turn the engine over (flywheel in place).

Vast majority of stator failures are short to ground faults (btw, stator FAR more likely to fail than CDI or spark coil).

 

[kevinfries]

it didnt vary when i turned it over, what does this mean?

 

[reelrazor]

Did you check it for cont. to ground first? Was there any?(continuity?). If so, the stator IS shot.

I didn't mean to check it while the flywheel was in different positions, but to actually hookup the ohm-meter and kick it. Actually you can set it to a/c voltage and do this and KNOW if the stator is doing its' job or not. A needle type meter is preferable to a digital for these tests, btw.

 

[Nevada Sixx]

a almost guarantee you its the stator, ive had to replace mine twice on my 89yz125. best way to replace that is to buy it with the harness and plate together, just unbolt, bolt on. those stators will fool you, they will show resistance but still no spark, last time i fell for that, i spend 450 bux on a cdi, coil,, only to find it was the stator again... also, check the wires on your kill switch by the hand grip to see if any wires are shorting out against the bars.

 

[reelrazor]

Yeah Nevada, I feel for you.

The manuals almost always give a resistance value through the stator, but rarely tell you to check for cont.to ground. THAT is how they fail, almost everytime. The insulation fails and they short to ground, or the windings break and continuity through them goes to infinity(and show as short to ground). If a stator shows continuity to ground, it has failed, no ifs, ands, or buts.

When I worked for a big Yam/Suzuki dealership and was going to factory schools on a regular basis they had warranty return numbers on coils, CDI's, and stators. They would request the parts back from the dealers to test. 80-90% of all CDI's and spark coils that were replaced on warranty were mis-diagnosed and were fine. There was a big push on to get technicians to replace only the real culprit and not to "parts swap" the problem gone.

Like I said in an earlier post, stators are FAR more likely to fail than any other component in the ignition. They have the harshest environment, stuck under the flywheel going from ambient(air temp) to hundreds of degrees and dealing with being solidly mounted to the engine and vibrating with it, plus the magnetic tug from the flywheel vibrating the stator coils themselves.

Oh, side note, of the CDI's that did actually FAIL, the majority of them were being run with non-resistor plugs which degrades the internal capacitor some thousands of times faster.

 

[zeaner]

kill switch......

no spark huh, i got the same bike and had the same problem and it turned out to be my kill switch on the handle bars was pinched and shorted to, to quickly check for this, unplug the water proof wire splices located somewhere behind the number plate and recheck for spark, if ya have a spark further your inspection to the switch it self, dean.