KLX 250 Rectifier ground mod - possible fix for ~6500 RPM stumble

This is an archive of the relevant information regarding the rectifier grounding mod that was discussed over at the Kawasaki forums pertaining to a fix for the stumble or miss that affected some KLX 250's at around 6500 RPM cruising speed.

Special thanks to Maine250SF for reporting his experiences with Kawasaki warranty work which is where most of the information on how the mod is to be performed and to David R for confirming an actual electrical anomaly with his diagnostic equipment.  The original thread can be viewed in its entirety here - http://www.kawasakiforums.com/forum/klx-250s-71/surge-6500-rpm-highway-speed-34470/


Basically the mod entails either cutting and re-grounding the black/yellow wire pictured here that runs from the regulator/rectifier to the existing factory ground, or splicing into this wire and adding an additional grounding path.   Most use the starter motor ground located just to the front of the rectifier plug as seen in the pictures of my modded ground below David's quoted post from the forum.


David R - post # 65 from http://www.kawasakiforums.com/forum/klx-250s-71/surge-6500-rpm-highway-speed-34470/

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This is the plug.

BLACK WIRE WITH YELLOW TRACER

I made my ground "T" in with the ground already there.  Its a ground in parallel.  Crimp on terminal on the other end of the wire and bolted to the engine using the existing bolt going to the same spot as another ground already on the motor just in front of the reg/rec.

I want this clear.  I soldered a wire to the back part of the terminal you see in the picture and inserted the terminal back into the plug.  Plugged it back in.  Motorcycle wiring was not changed, cut or removed only extra ground added.
This is what I was getting occasionally

This is more like what it should be

I ran the bike for a few minutes after doing the repair and saw only normal spark traces.  I am going to check the grounds to the CD box and coil.

40 miles, and I THINK its fixed.   This inculded an attempt to do 80 on an expressway.   Pavement is grooved and enough traffic that the bike was not too stable so I backed off to 70-75 mph.  It seems to run great.

David

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Here is a picture of the finished mod on my bike.   Remember to make sure if you are cutting the wire to ground the plug end of the wire that is attached to the white box that plugs into the rectifier and not the end that runs into the wiring harness with the other wires to the original ground.  Grounding the wrong end will result in your battery not being charged and eventually the drained battery will cause the bike to die on you.