Knocking at idle only

[Big_B]

Had my '93 k1100 for about 6 months now and enjoy the bike. Got it with 56K on the clock and currently has 68K. I've gone thru the bike fairly well and got it running decent. The issue I'm having now is a mechanical knocking sound only at idle. The knocking goes away right off idle and the motor never knocks at any other rpm. The noise does go away slightly when I release the clutch in gear at idle. And the noise varies when I pull in the clutch in neutral too. Yes the clutch did start slipping in top gear, but grabs well now which I find odd. :hmm: Has anyone heard of a clutch knocking? It doesn't seem like a bottom end knock to me.

I'm open to any ideas on what this could be and what to test on it to figure it out. Def hoping this is a something simple as I've already experienced sticker shock every time I step foot in the dealership. :yow

[Rick G]

Have you done a sync on the throttle bodies. That out of sync will cause uneven idle which shows up as a knock.

[frankenduck]

It may also be that your alternator bushings are wearing. (a.k.a. monkey nutz)

Is your bike an RS or an LT?  (93 LTs had the 32 amp alternator while 93 RSs had the 50A and they employ different ones.)

[Big_B]

No I havent synched my throttlebodies.

It may also be that your alternator bushings are wearing. (a.k.a. monkey nutz)

Is your bike an RS or an LT?  (93 LTs had the 32 amp alternator while 93 RSs had the 50A and they employ different ones.)

It's an RS.........how would I check for it being an alternator?

[frankenduck]

No I havent synched my throttlebodies.

It may also be that your alternator bushings are wearing. (a.k.a. monkey nutz)

Is your bike an RS or an LT?  (93 LTs had the 32 amp alternator while 93 RSs had the 50A and they employ different ones.)

It's an RS.........how would I check for it being an alternator?

"Knocking" sound will come from near the rear brake reservoir under the right battery cover.  Probably not a bad idea to replace them anyhow- only about $20 for 3 of them from a dealer.

[Big_B]

Ok I'll look into it more and let you know...thank you for the suggestion.

I also need at least a front drive shaft half a.s.a.p. if anyone knows of one for sale. :2thumbup:

[wmax351]

Also can be the cam chain: the tensioners can be funky at idle.

[sh00ter]

If I might hijack / or amend to this; The question I have is how does one know a "good" idle?  Not the RPM, but the feel/sound - any empirical or rules of thumb to know if the bike sounds / acts right at idle?

[wmax351]

If I might hijack / or amend to this; The question I have is how does one know a "good" idle?  Not the RPM, but the feel/sound - any empirical or rules of thumb to know if the bike sounds / acts right at idle?

Usually it is a matter of feel. It should be smooth, and cleanly come off idle with throttle.

[frankenduck]

Most K1100s sound like a box of rocks at idle.

[sh00ter]

Most K1100s sound like a box of rocks at idle.

Perfect - Mine goes like a bat out of hell, starts and stops smoothly, etc.  Idles good from start, once you give it a blip to even it out ... .  and sounds like a box of rocks.   :lol: :lol:

[TimTyler]

... a mechanical knocking sound only at idle. The knocking goes away right off idle and the motor never knocks at any other rpm. The noise does go away slightly when I release the clutch in gear at idle.

I had the exact same symptoms before I adjusted the valves.

[BobZ(IL)]

It may also be that your alternator bushings are wearing. (a.k.a. monkey nutz)

Is your bike an RS or an LT?  (93 LTs had the 32 amp alternator while 93 RSs had the 50A and they employ different ones.)

The alternator cover on my 01/93 reads 50amp and has that part number. Wonder if PO upgraded.

[frankenduck]

Wonder if PO upgraded.

Wouldn't be surprised.  It's a pretty easy thing to do.  I did it to my 93 LT many moons ago.