Odd intermittent stall becomes weird bucking, 94 K1100RS

[BoardOfCan]

For the past 2 weeks or so, I've had a VERY intermittent electrical mystery - going full speed on the interstate, bike would suddenly stall hard, for just a second, and the dashboard bulb failure indicator woudl come on, suggesting that the bike restarted (possibly stalled and then pop-started by sheer force of momentum). I checked for loose battery connections or evidence that the contacts might be arcing on the motronic mounting bracket...everything LOOKED ok.   
Last night, setting off for home, I came to a stop sign and when I started again, dash lights started flashing and bike bucked wildly and rhythmically. Pulling in the clutch, idle was normal and smooth. Revving produced no odd effects. Only under full clutch release and load, bucking started again. Switched bike off, reset, started again, same behavior. I limped back to my shop and tried it around the lot after a restart, problem was gone. For now.
Any ideas what this could be? I plan to go through ALL electrical connections this weekend. Fuel pump is new. Injectors are clean.

[Skunky]

I would check your ignition switch they can get dirty and cause problems. Also check the ground under the tank and from the starter. Which again can make weird things happen. All of the electrical connectors can suffer from poor connectivity when a bike is old. It’s worth pulling them apart spraying with an electrical cleaning spray and reconnecting.

Good luck

[Laitch]

Because you worked on the alternator in July, Skunky's suggestions concerning ground connection integrity are particularly relevant. Check the Motronic plug for a clean and tight connection. Use DeoxIT D5 for cleaning connections. Consider, too, intermittent fuel starvation will also stall the moto and turn on instrument lights so check your fuel filter, fuel connections within the fuel tank and the external fuel pump electrical connectior. These are the easiest conditions to rule out first.

[BoardOfCan]

Thanks to both of you, those are awesome starting places.

[The Mighty Gryphon]

Clean your ignition switch.  At this point in time it's starting to accumulate a bunch of dirt and corrosion in the contacts.  It's an ugly job, but it needs to be done sooner or later.

Here's how to do it:

http://www.motobrick.com/index.php/topic,10504.0.html

[BoardOfCan]

The security bolts are still intact, what’s the preferred way to get ‘em out? If drilling what size?

[The Mighty Gryphon]

You have to drill them out.  There is a centering dimple in the head of the screw. 

The screw is an 8mm.  I would use a 8mm or a 5/16" drill.  Once the head is drilled off, you should be able to remove the switch, and then use vise grips to remove the screw.

Replace the screws with fillister head screws you can install and remove with an Allen wrench.

[BoardOfCan]

And now it's bottoming out on the bracket holding up the front fairing. I guess either that comes off or the top clamp does?

[Laitch]

And now it's bottoming out on the bracket holding up the front fairing.

These instructions are for a 4V K100RS with the same lock housing as your moto. Any help?

[BoardOfCan]

An amazing help. I’m the kind of genius who went full lock to the left, got frustrated, went home for lunch. Thanks!

[The Mighty Gryphon]

An amazing help. I’m the kind of genius who went full lock to the left, got frustrated, went home for lunch. Thanks!

Glad you read the instructions the second time they were posted.

[Laitch]

Glad you read the instructions the second time they were posted.

It's all in the packaging. 

[BoardOfCan]

Glad you read the instructions the second time they were posted.

And what, vexed about me reading them the first time? First question not addressed in the post. Second question was my very special blend of dyslexia and dumbassery: I know which hand I write with, but “right” and “left” will never quite stick.

[Laitch]

Enough about you, BoC. Where are you on this switch housing removal project?

[BoardOfCan]

It went great! Contacts were filthy (of course), it came back together easily and I took a 2 hour ride without any issues. Now I need to clean up the side stand switch...

[Laitch]

Thanks for the update.  As has already been suggested, inspect and clean all electrical connectors as you encounter them.

[BoardOfCan]

While I had the tank off, I went through most of the under-tank-to-fork-downtube ones with Deoxit yesterday.

[BoardOfCan]

And the actual culprit was: FAILING KICKSTAND SWITCH! But now my connectors and ignition are clean, so I'm happy about that!