Strange whining/whirring noise from my K1100RS - any ideas?

[JonnyB]

Hi,

Got an odd problem, the bike makes a strange noise intermittently. Usually when idling or pulling off at the lights but also sometimes when riding although it can be tricky to tell against the engine and wind noise. I thought it was he suspensionat first, as it seems to start/stop when putting force on the front suspension, but it stops as soon as I turn the engine off. Is there a rotating cable linkage for the rev counter or anything like that? Not even sure if that’s a thing. It sort of sounds like it’s coming from the clunky speedo box or something, but really can’t be sure - here is a video so you can see what I mean:



Obviously sounds a bit worrying but he engine runs fine with no throttle issues or loss of power. Clutch also seems fine, plus I wouldn’t imagine it should make the noise when in neutral if it was the clutch so I’m guessing it’s something linked to the engine but not necessarily the engine itself.
Anyone encountered this oddity before.
Thanks Jon

[daveson]

Since you suspect the instrument cluster,  remove the transmitter from the final drive and see if that makes a difference.

[Laitch]

Is there a rotating cable linkage for the rev counter or anything like that? Not even sure if that’s a thing. It sort of sounds like it’s coming from the clunky speedo box or something,. . . .

Thanks for a posting a useful video. There is no rotating cable for the tach or speedo. These components are electronic.

Use a screwdriver as a stethoscope by putting the handle up to your ear and the blade against various components while that whine is being heard. You might be able to isolate the area of the noise that way.

[K1300S]

sounds like a fuel pump in its last death throes.....try putting your ear against the left side of the tank while noise is there...

[koapono]

I agree with possible fuel pump issue.
open the fill cover, start engine and see if noise becomes louder or amplified.
many after-market pumps out there that work.
g'luck

[The Mighty Gryphon]

+1 on the fuel pump.  I see the low fuel light is on in the video along with the fuel gauge on "empty".  The pump in my K75RT howls like a banshee when the fuel gets down to 5-6 liters.

You might want to check the mount down in the fuel tank.  Make sure it isn't loose.

[Laitch]

I see the low fuel light is on in the video along with the fuel gauge on "empty".  The pump in my K75RT howls like a banshee when the fuel gets down to 5-6 liters.

If you locate the sound as coming from the fuel tank, this service bulletin applies to all classic K motos. Rerouting the hose could help to eliminate the noise produced by fuel starvation.

[riots100]

I just fixed this issue on my K100RS.  It was a fuel pump issue where the fuel pump was getting starved due to sediments in the tank clogging up the strainer.  Cleaning out the tank and the strainer fixed the issue and eliminated the whining noise.  No fuel pump replacement was needed.

[JonnyB]

Hi yes I’m certain now it must be the fuel pump. I.e. in that video the fuel level was resting on the empty limit... I put some more fuel in and the noise stopped! Amazing, but wondering is this a problem waiting to happen or just because it was trying to pump air/fuel or maybe the fuel lubricates the pump normally. It’s about 70k miles so I wouldn’t be all that surprised if it is getting ready for retirement.

Thanks for the advise

[JonnyB]

Just read the last message - good suggestion I will give it a clean out when I get the chance

[The Mighty Gryphon]

I would guess that unless there is something else at play in your case beyond low fuel level, your fuel pump should be good for a few thousand more miles.  The pump on my bike has been howling now at low fuel for about 5 years and 40,000 miles that I know of. 

Annoying, but not critical.  Just don't try to run every last drop of fuel from the tank before you fill it.

[mw074]

Check the fuel pump vibration damper. It may be going south.