one cyclinder firing...no spark...2000 M750

[oldschool55]

Ok, so my bike is only running on the horizontal cylinder.  The vertical cylinder is not getting spark.  It initially cut out for about 10 minutes, then returned to normal, intermittently for about 15 minutes, and now I haven't gotten any spark since.  Plugs were replaced, wires checked, even swapped coils around and still only the front cylinder gets spark.  So the coils are fine. 

I am afraid to ask what it might be...Any ideas?

Thanks,

Dave. 

[SP3]

You've seen the pic I posted on the other thread. I will assume that you also have the small boxes on either side as well. Swap them cylinder to cylinder to chase the spark. Did you actually measure the primary and secondary resistance of each coil? Also, even if the wires don't LOOK bad they can still leak if a ground is close enough to a weak (enough) spot in the insulation.

[oldschool55]

You've seen the pic I posted on the other thread. I will assume that you also have the small boxes on either side as well. Swap them cylinder to cylinder to chase the spark. Did you actually measure the primary and secondary resistance of each coil? Also, even if the wires don't LOOK bad they can still leak if a ground is close enough to a weak (enough) spot in the insulation.

I am working my way back from the plugs to determine what is wrong.  I re-did the connections for the plug caps as well as the on the coils.  I swapped the coils as well as the small boxes next to the coils.  Nothing changed.  I am frantically looking for my volt/ohm meter, but am struggling to find it.  What is next in line to check?

[ducpainter]

There have been several incidences of bad pick ups or bad wiring from the pick ups also.

Check the resistance of the pick up coils.

They should be the same.

[oldschool55]

Thought i would add after thinking more about it...

It almost seemed to be caused by a bump in the road.  It went out right after i hit a large pothole.  Maybe this will help.   
 

[Howie]

Ducpainter is probably correct about the pick ups.  The ignition modules go bad also.  It is easy to switch modules.  If the other cylinder is affected it is a bad module.  I had a pick up go intermittent on my bike.  The pick up would test good until real hot, boil for 5 minutes and it would read infinite resistance.

[SP3]

.... boil for 5 minutes and it would read infinite resistance.

Great trick, howie.

[oldschool55]

Ducpainter is probably correct about the pick ups.  The ignition modules go bad also.  It is easy to switch modules.  If the other cylinder is affected it is a bad module.  I had a pick up go intermittent on my bike.  The pick up would test good until real hot, boil for 5 minutes and it would read infinite resistance.

How do I go about checking the pick ups?  I have not worked on these parts of my bike before. 

[printman]

there are 2 sets of wires coming out of the left case. 1 set of yellow wires goes to the rectifier/regulator (charging system)

The other is the pick up signals for the ignition, which travels up to the ignition modules. There should be some connector between them that can be unplugged and check the resistance of them. They are to be close to 100 ohms on the 900, should be very similar on a 750.

[Howie]

The wires from the pick ups go directly to the modules.  Each module has two connectors, one 2 wire and one 3 wire.  The 2 wire connectors are the pick ups.  As printman says, 100 ohms, 5 ohm tolerance.

[oldschool55]

Thanks guys!!!

And that reminds me, i need to replace my regulator as well...

My multimeter went MIA, so tomorrow i will pick up a new one.