Possible electrical issue causing dead cylinders

[Wayn-O]

I'm not really sure what is happening, but last time I had my bike out, it started up and idled just fine.  Started riding along and it started sputtering while accelerating, and was sounding like a v-twin.  I pulled over and my idle has dropped significantly (down to like 200 rpm).  I try going again and it will cut in and out from power firing on all cylinders to instantly loss of power sounding like a v-twin.  Back and forth multiple times.  I turn the bike off, wait a bit, turn it back on, then it idles/revs fine, and 30 seconds later, rpms instantly drop and it's running poor again.  When I get back to my garage I could smell gas, most likely coming out of the dead cylinders.  Ride it to work this morning and it seems to be running just fine.  Very strange.
I am suspecting a possible electrical issue because it will come and go so instantly.  Also, when I had pulled over and turned it off, i did try opening the gas cap just to rule out a kinked vent line.  No change. 
Another reason I am suspecting it to be an electrical problem is that leading up to this my voltmeter has been reading 13.5 or 13.6 lately, instead of it's usual 13.9.  But when the problem was happening, the voltmeter was back to 13.9.  I dunno.  My ride to work today the voltmeter was sitting at 13.6, but seems to be running okay.
What should I be checking?  ICM?  Coils?  What?

[Pete]

If you are at 1/2 tank of fuel or below, go to reserve next time you have the problem. If that solves it fix the failing petcock.

[Ricky-D]

I would suggest to give the engine a couple heavy treatments of a gas treatment like Techron or B-12. Your problem sounds like something connected to running ethanol enriched gasoline.

***

[Roidfingers]

If you are at 1/2 tank of fuel or below, go to reserve next time you have the problem. If that solves it fix the failing petcock.

+1

And check your vacuum line from #6 intake.

[Steel cowboy]

Here is my 2 cents worth, if your pepcock if failing or your vacumm line coming off number 6 cylinder is bad ( left side rear manifold) you might be loosing your vacumm causing a decrease in fuel to your carburators. Your pepcock works only when there is vacumm to open it up, no vacumm no gas flow. A bad diaphragm could have the same symptoms. If you disconnect the fuel line from the pepcock there would be no fuel comings out and if you install a long vacumm line on the vacumm side, suck on it it will open the pepcock and you should see fuel flowing from it. My interstate pops when I forget to reopen the pepcock after parking it. It might run a mile or two before.
Check these two first, it's cheaper than chasing an electrical issue. Electrical issues can get expensive real fast.

[Wayn-O]

Thanks guys.  I'll test this out.  Maybe time to get a pingel valve. 

[sdv003]

Check the grounding and verify the neg side of the battery is tight.  While its likely to be fuel related, my experience with bad ground had me fooled and chasing fuel issues for days before i found the issue.

[Ramie]

More than likely a fuel problem but if you can determine what cylinders are not firing it would help as it could be related to one of the coils.

[Wayn-O]

Since posting this, it has not occurred again.  I will take all of your advice into consideration and I will post again if it starts giving me trouble again.  Weird.

[Led]

Since posting this, it has not occurred again.  I will take all of your advice into consideration and I will post again if it starts giving me trouble again.  Weird.

That is what I was wondering!  Did you just wash the bike, before riding it??  ESPECIALLY with a "pressure" wash?

Water into places where it usually should not be, can really raise heck, until it all dries off again!!

Happy to hear things are AOK again!