[jag13]

I am doing some volunteer work on an '07 Yamaha 650 V Star Classic. The owner rode the bike one day and everything was fine. The next day the bike wouldn't start, and was diagnosed as having no spark on either cylinder.

I picked up the bike and brought it to my place to work on it. Upon unloading it, it fired right up and ran fine. I test rode it and everything worked as it should. I shut it off, then restarted it and rode it again. When I returned, I let it idle it for a few minutes, then it killed on it's own, and would not restart. Again it had no spark on either cylinder. I let it sit for approx. 20 minutes, and it started right up again. I shut it off, and it restarted again. I let it sit for a couple hours and was going to start it...No spark again.

When it was running everything worked. Battery is good, and getting charge from the stator. And when starting, the motor cranks like it should.

I have determined that it is an issue with either a failing CDI box, or failing stator pick up coil.

So my question is would the pick up coil work intermittently? In my experience they either work or they don't.

This is volunteer work, and the wires from the stator coil are in a position that would require some SERIOUS disassembly to even get to the wires to perform any electrical testing. I don't want to tear the bike down that far just to perform a test. And the local shop said that they can't test the CDI box, they just go by process of elimination to determine if it's bad.

 

[jag13]

Very unlikely that the igniter / computer is the problem.
You might be on the right track in thinking that the pick up coil could be involved. However, I've never had one to work sometimes then fail, work, fail. Like you said, they usually work or not.
That sounds exactly like a bad connection or switch somewhere.
I think I'd start by inspecting the wires and plugs going to the pick up coil and Ign. coils.

Yup, did that. all wires and coatings look great. Also I would expect a short to either blow a fuse or drain the battery, or disrupt a system (lights, horn, indicators, etc.) during the test ride. But when it gets spark it starts, runs, rides, and all elec systems work perfectly. When it did die once for me, it was at idle. I touched nothing but the key and start switch. never wiggled the bars or touched the bike in any other way, just let it sit...and spark returned...then disappeared.

 

[jag13]

I just did some further dis-assembly which allowed me to trace the stator/pick up coil wires and locate the proper plug in locations. So my next question is how to check it. There are five wires separated into two plugs, 1 with 2 wires and 1 with 3 wires, that come from the stator cover. I believe the pick up coil is the 2 wire set. Using a multi meter, what should I be looking for?

 

[jag13]

Thanks Nick. According to their info, I need a new pick up coil. As mine gives no reading at all.

Parts are on order. I will update when the installation is complete.

 

[jag13]

UPDATE: Issue was indeed stator coil pick up sensor. Replaced, and runs great again! My 72 yr. old Mother will be very happy!