K75 - new noise

Hi,

Yesterday I was out riding, and about halfway through the trip, the bike started making a new noise.. If I had to describe it, it sounded like crickets or locusts chirping, except higher pitched and faster. It seemed to go up and down as I revved the throttle. The bike ran just fine, but I don't want to let something go that might be catastrophic later on...

I tried to pinpoint the location of the sound while at a stop, and it sounded like it was coming from under the gas tank.. but I may be mistaken about that..

I also noticed that when I stopped and turned the bike off and back on, the sound did not come back until I was about 5 miles down the road.. i.e. it didn't come on right away.

could this be a fuel pump? What would be the best way to determine what the problem could be without disassembling half of the bike trying to find a phantom noise

Thanks in advance for the help!

Maybe your alternator bearing is on the way out? I don't know but the sound you describe sounds like an alternator bearing to me.

Alternator tip:

If it turns out to be the alternator you may well consider replacing it with the later model 50 amp job---same dimensions, bolts on and you're good to go with aux lights, heated clothing, etc.

I'd start checking out beemerboneyard, the Flea Market and IBMWR just in case it is the culprit. (Kent's idea sounds on target to me though I'm certainly no expert)

Almost bolt on The electrical connector is different. KBikeParts.com sells used 55A alternators and includes a little wiring pigtail to make the install easy.

You might want to open the filler cap while it's making the noise to make sure it is not the fuel pump before you start chasing something deeper.