Buzz and Shake

[mgalie]

1987 K75s with 34000k.

The problem, or is it?: Shaking/buzz kind of thing at low revs 1500-2500 rpm with either the clutch in or out. It's not very strong; I don't feel it in the handle bars, but more on the foot pegs. It occurs consistently. But, there's no buzz once the rpms are out of that range. I just started noticing it about 50 miles ago.

Hypothesis #1: I replaced the clutch and bell housing 400 miles ago. I didn't have a big enough torque wrench to put PN 15 to spec (I forget the value, but it was pretty high and I tightened it till I couldn't move it no mo'). Could that be it? From what I've read, it being loose causes a BIG shake and is noticeable across the rpm range. What I have is just a buzz.

http://www.realoem.com/bmw/showparts.do?model=0572&mospid=47908&btnr=11_1801&hg=11&fg=10

Hypothesis #2: Paranoia. It could have always been like this and I'm just being more attentive to it now. Also, I have recently been doing more slow in-traffic riding than ever. Normally, I would just shift through this rpm range. Also, having never ridden another K, I've got nothing to compare it too.


Thanks,
Michael

 

[deilenberger]

1987 K75s with 34000k.

The problem, or is it?: Shaking/buzz kind of thing at low revs 1500-2500 rpm with either the clutch in or out. It's not very strong; I don't feel it in the handle bars, but more on the foot pegs. It occurs consistently. But, there's no buzz once the rpms are out of that range. I just started noticing it about 50 miles ago.

Hypothesis #1: I replaced the clutch and bell housing 400 miles ago. I didn't have a big enough torque wrench to put PN 15 to spec (I forget the value, but it was pretty high and I tightened it till I couldn't move it no mo'). Could that be it? From what I've read, it being loose causes a BIG shake and is noticeable across the rpm range. What I have is just a buzz.

http://www.realoem.com/bmw/showparts.do?model=0572&mospid=47908&btnr=11_1801&hg=11&fg=10

Hypothesis #2: Paranoia. It could have always been like this and I'm just being more attentive to it now. Also, I have recently been doing more slow in-traffic riding than ever. Normally, I would just shift through this rpm range. Also, having never ridden another K, I've got nothing to compare it too.


Thanks,
Michael

Michael - to eliminate #2 - paranoia (I'm very familiar with this..) find another K75 to take for a ride. Do that before worrying about #1. If you undertightened the nut and it was coming loose (not at all likely - it's a locknut) - the clutch adjustment would start changing on you.

Question - did you mark all the clutch components before disassembly and reassemble them the way they were? Or did you find the factory balance marks and use them (spaced as far apart from each other as possible)? While balance (in my experience) isn't quite as critical as the manuals all say - it might cause a buzz/vibration if it's off.

But - first things first. Find another K75 to take for a ride.. and see if it's real or imagined.

 

[mgalie]

Thanks Don.

I marked all the clutch stuff myself: no factory marks. I took extra care to mark and realign them, so I hope that's not it.

Now to find a K.... Maybe the dealership up the rode will let me ride theirs.

 

[mgalie]

Took the bike to the local dealer today. Didn't get to ride another K, but the head tech (the only one, really) looked at it and was not perturbed. He wrote it off to the new transmission: will check the drain plug for metal.