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Discussion Starter · #1 · (Edited)
I have a 2001 M750 thats only firing one plug. I tried swapping the two coils. Not the coil. Switch the wires going to the coils and it follows the wires. Checked connections etc. No broken wires. Anyone have ideas what this could be or what I can check to diagnose it?

Thanks
 

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Check coil pick-ups! Should be about 100-120 ohms each. Change the CDI black boxes over, one side to the other and see if it changes.
 

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Had the same thing on my 98 M750, turned out to be corrosion running along the earth cable to one of the modules soldered in a new cable all good again.

Jack
 

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Discussion Starter · #4 ·
01 M750 only spark on 1

The CDI black boxes.. are they the two boxes located right beside the coils with a two wire and a three wire connector on them? If so I tried swapping them too. Problem didnt follow the black box.

I notice both coils have two posts. one post has two red wires attached and the other post has a grey wire on one coil and a black/red wire on the other coil. the problem seems to follow the grey wire.

How can I diagnose to see if it is a coroded ground wire?
 

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Yes the CDI modules are next to the coils and they have 5 wires each, two to the pick up's a positive and negative and one to the coil you should unplug them
and check with a multi meter if you have good connections. The right hand module and coil fire the horizontal cyl, do you know what cyl is not firing.

Jack
 

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Discussion Starter · #7 ·
01 M750 only spark on 1

OK I have not measured the ohm yet however I did try swapping the two 2 wire connectors coming from the pickups going to the CDI black boxes. The problem did not follow one of the pickup wires.
 

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Discussion Starter · #8 ·
750 only spark on 1

Problem ended up being the tach. Followed the grey wire the problem followed and it led to the tach. Unplug the 3 wire connector on tach and cyl started to spark! Tach was out of a 750SS and although has exact same connector/wires it apparently is not compatable.

I swapped this tach out months ago when I first stared my restore on the bike I had just bought. So with the tank off getting painted I didnt try to run the bike with the new tach.

Thanks for all the help

Silly!!
 
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