Alternator?

[hoser]

Riding in the rain, I35 North of Des Moines.  Hit the air horn to stop a car from cutting me off.  The horn sounded and the engine sputtered.  It stopped sputtering when I let off the horn, Kury
LED went to yellow at the same time. went back to green when I let off.  Brushes, ya think?  Never done it before, bike has 70k on it, never had alternator out. Had the driving lights on at the time for maximum visibility. Hoser 

[NITRO]

Or maybe your battery needs to be replaced.

[JetDriver]

Don't know the answer, but it sounds easier to check the battery first.

[hoser]

I'll do that. hoser

[timk519]

I lost an alternator at around 50K miles, so it's not unheard to lose one at your bike's mileage.

[Valker]

I agree on the battery. I run an air horn (Stebel Nautilus) 90/100 watt headlight, moto lights, and a pair of PIAA 510s. My lights dim when I honk.

[hoser]

It was a bad ground on the battery, you could actually see and hear it spark when I hit the button.  "Much ado about nothing", to quote the Bard.  Hoser 

[JetDriver]

Glad you found it rather quickly.  Sometimes bad grounds take forever to find, and in the meantime you're doing everything else you can think of to the bike.