metallic screaching sound on cold start -up

[John M]

cold weather (-2 celsius ) started bike got a sound I can best describe as being like a worn out water pump on a car. the sound came and went through 10 min of riding. Also I noticed some drag in the transmission when in neutral and releasing the clutch lever ( the bike edged forward slightly )

[montmil]

I would first do an inspection and/or adjustment of the clutch cable; although the ,"when in neutral and releasing the clutch lever the bike edged forward slightly," is worrisome.

The "screeching" might be a throw out bearing gone bad.

If you have a mechanic's stethoscope -or a l-o-n-g screwdriver- you may be able to locate the source of the noise and better troubleshoot the issue.

Monte  

[tvrla]

I suspect the throw-out bearing. It's possibly not rotating as it should (due to cold stiff oil) in the bore and the screeching is the end rubbing in the spring (or whateve that part is it lands in).

[Bob_Roller]

In cold temps with heavy gear oil in the transmission, with the bike on the center stand and the rear wheel off of the ground, the rear will will rotate in neutral with the engine running .

If you don't find anything with the clutch rod/throwout bearing, a slight possibility of the starter gear not returning all the way when the starter shuts off .

[John M]

Thank you all for your suggestions, the clutch throw out bearing was not something that occurred to me as a possibility. the starter gear not pulling back fully was something I was considering. What really spooked me was the slight tug I felt when releasing the clutch lever when in neutral ( this occurred several times ) That said problem inside transmission to me ( the bike is a 1986 with 92k km on it and it is without the circlip on the output shaft ) I plan to drain the tranny oil for inspection even though it has only been in for 3 months , and proceed from there also looking at the other suggested items . I have been preparing for the eventuality of getting the transmission rebuilt, however it may be a little sooner than I had anticipated. I think I jinxed myself only a week prior when speaking to a friend in the vintage club about how beautifully the bike was running and I had just finished installing a 4 piston front brake caliper from a 1999 oilhead and was going out to test it and bed in the pads when the racket started, the caliper by the way is a great upgrade from the 2 pot Brembo.   Best Regards John Muir

[tvrla]

John - some info, please, on the caliper swap! Was an adapter bracket needed, or just shaving the mounts a little?

You don't think you can just waltz in here with a statement like that and leave quietly, do you???

What weight oil are you running in the transmission? Even if it's the correct weight for the temp, it's possibe it just got so stiff from the cold that some of the forces from the input showed up at the output.

Another possibility is the throwout bearing is hanging up in the bore. That's also a common problem - especially on the newer 100GSs. It's made of a plastic material that swells a little and hangs up in there. Don't buy a new one, it'll just do the same. Instead, carefully sand down the diameter until it's smooth in the bore. Frankly, I think that's your problem.

[John M]

If you have the 2 pot brembo calipers with 108mm spacing between mounting bolts o.c. then the early oilhead brembo 4 piston calipers bolt on directly they give you more than 50 % more swept area on the disc and in my case give more feel at the lever. the calipers need a little aluminum shaved off so that they center perfectly on the disc.I was able to do the metal removal with my woodshop tablesaw by clamping the caliper to the fence raising the running blade slowly into the mounting lugs ( using an 80 tooth carbide blade ) thus avoiding the cost of a machinist.   In my case the amount of metal removed was 4.7 mm
You have to test mount the caliper without pads to determine the correct amount of metal to remove. Snow Bum writes about this conversion

[lodekka]

Is the noise similar to that of mine which is on: - You Tube  - BMW motorcycle R65 engine squeal. I fitted a new plastic bodied bearing assembly and clutch rod prior to this noise starting. I did release the clutch arm, partially withdraw the rod and then start the engine but it still made the noise. If it is the Plastic housing OD then I might just pluck up the courage to do it this winter as the bike has been laid up a year a I thought I had a major engine strip on my hands so other work took preference.

[John M]

the squeal you posted on youtube sounds identical to what I have, I hope others will listen to the video and give their opinions

[tvrla]

Could you post a link to the youtube screech?

if the throwout was partially disconnected, it doesn't sound like the problem.

Can you tell which end of the engine the sound comes from?

Ok, I found the video:

http://www.youtube.com/watch?v=sNkB1DivMnk

It doesn't sound serious to me, especially the way it comes and goes. But I can't tell from the video where it's coming from.

We need more data to diagnose it, so some experimenting is needed - what happens when the engine is revved? Or the clutch is pulled in? Clutch in, but in gear? etc...

Does this only happen when cold?

It could still be the throw out bearing... does the clutch pull hard sometimes, or act not quite right? That plastic part has to slide in the bore, but if it's tight, can hang up.

[John M]

I just did a search titled      youtube bmw motorcycleengine squeal  
that brought it up

[lodekka]

Listening with a large screwdriver I believed the noise was coming from the clutch area. When the engine first starts then is no noise then within a minute it starts. Pulling the clutch in made no difference. Since the noise started I have not run it long enough to see if it disappears when the engine is warm.
It has been off the road for 12 months or more now as I believed it was a major strip down.

[Bob_Roller]

If you have any problems removing the pushrod, there is a threaded hole in the end of the pushrod .

It's a small diameter fine thread, don't know if you can find a threaded fastener in the correct size to thread into it, then pull the pushrod/bearing out .

[jg928s4]

Mine does similar at odd times, I thought it was not going all the way into gear or clutch throw out not disengaging.  Because when I stomp on shifter, or pull clutch in and out it stops.  Only occurs when cold engine and it is cold out, guessing fluid not as viscous....

[wiemer]

@ John:

cold weather (-2 celsius ) started bike got a sound I can best describe as being like a worn out water pump on a car. the sound came and went through 10 min of riding. Also I noticed some drag in the transmission when in neutral and releasing the clutch lever ( the bike edged forward slightly )

Still makes noise when  clutch released and in neutral?


....Maybe some dry sprockets in the tranny, on the shafts? That would explain  the bike creeping.
If one gear makes that bonding problem, one gear should be noiseless.

A dry, or dying bearing in the tranny, but that doesnt provoke the creeping.
You could lift up the bike, roll her over vertically up & vertically down, to grease dry tranny bearings...I know, hard to perform.
What is being done in cars is fill the tranny up way above max, drive a bit, and drain till normal level. might (sp)oil your clutch plate though....

I am curious, Wiemer.