loss of spark, how to check stator?

[seff23]

i'm helping my buddy fix his 500 and its supposed to be an 91 but who who knows whats been done to the motor or even what year it is but we were out riding and his just quit and wouldnt start back up, so we check everything over and can come up with anything, his flywheel and stator is different from mine his flywheel is smaller and he has 2 pick up coils one big one and one little one so i'm kinda stumped how to check them? anyone know how to check them or what year its from? or any idea to try to see if we can get some fire from the coil?

[kxracer]

We had this on my mates RM 250, it ran fine, then suddenly it would not start.
Unlikely to be the coil or CDI.
Check the resitance of the stator and coil with a multimeter, the range of settings are in the manual.
The distance between the pick-up unit and the flywheel needs to be between .05 to 1 mm (maximum).
Also ensure the earth connections are clean.

I would also get him to completely clean the carb and make sure the pilot screw is also set correctly (normally 1.5 turns out from fully in, but check the manual), easy to do and perhaps the first job as the easiest and cheapest. Then check the spark plug (or replace it) gap and that it has no carbon to allow current leakage to earth.

The RM had a mucky pilot jet and combined with a large gap between the pick up and flywheel. He had bought a new stator, we cleaned the carb and closed the gap for the pick-up to 0.5mm and it fired 5th kick with choke.



Happily riding now but it cannot catch a KX

[Enduro Addict]

I also had the same thing on my sons YZ125.  It turned out to be a bad kill switch.  That is real easy to check without have to go into all the other testing.  Then is that does not work, I would move forward with the rest.