metallic screaching sound on cold start -up

[tvrla]

By the way, it's normal for the rear wheel to creep with the bike on the center stand, engine running and in neutral. But if you hold the tire the movement will stop.

[fermin]

mine creeps too, I think its normal

[John M]

The creeping I referred to in my original post was with the bike off stand in neutral, when I released the clutch lever the bike tried to nudge forward this occurred several separate times . Very worrisome, I am going to drain the tranny tomorrow morning to inspect the gear oil for any telltale signs of a disintegating bearing before moving on to other suggested items (the oil was changed about 3,000 km ago in the summer and at that time the old oil I drained looked good and there was nothing other than a little grey paste on the magnetic plug.

[John M]

Drained tranny this am  , old gear oil was pristine no metallic bits of any sort. so on to clutch throwout bearing and then re & re of starter motor

[tvrla]

No metal bits in the trans oil is always good news! Now on to the cheaper problems.

That's a big relief!

[wiemer]

Hi,

I posted the Youtube squeaking BMW on the German R45/R65 Forum (KleineBoxerForum), and somebody came up with this.
What is interesting he actually did not listen to the Youtube sound because of primitive computer (!), but he mentioned that on his bike, when the crankshaft rear main O-ring was going to die, he heard noises, like from a driving belt! After that, oil is coming out between the 'box and engine.
(he changed the O-ring 3-4 times. in 33 years)
(Others suggested rockers or valves, but that is not likely.)
Something to be ruled out, before opening up the gearbox!

Groetjes, Wiemer.

Hallo zusammen,

ich kann mir mit meinem langsamen Rechner zwar kein Youtube anhören. Aber wenn Ihr so etwas wie Keilriemen-Geräusch als Vergleich angebt: Wenn der hintere Kurbelwellen-Dichtring sich verabschiedet, kriegt er auch das Quietschen, weil die Dichtlippe zu breit wird und bei Mangelschmierung den sogenannten Slip-Stick-Effekt zeigt. Meine Kurbelwellen-Wedis (Wellendichtring DIN 3760) haben sich vor der deutlichen Leckage immer akustisch angekündigt. (Verbrauch drei oder vier Stück auf 150 Megametern in 33 Jahren)

Und weil ich das Quietschgeräsch nicht zuordnen konnte, habe ich auch schon mal den ganzen Zylinder abgezogen, um zu sehen, ob der Kolben vielleicht Freßspuren hat - hatte er nicht.

Guten Rutsch - aber nur in ein gesundes 2012 - nicht auf der Straße.

Brummbär/Michael
Brummbär
Brummbär
Dauerposter

 
Beiträge: 95
Registriert: Mo Feb 26, 2007 14:23
Plz/Ort: 28357 Bremen
Motorrad: R45 mit RS-Verkleidung, Sept. 1978
R1200S als Zweitmopped(Tschuldigung)

[Air4Life]

I think this was already mentioned; but just in case, it may assist in your diagnostics:  Does the sound change in relation to engine speed?  Do you believe it has a speed that matches the crank, or some other speed?

[John M]

the noise goes up and down with engine speed

[Air4Life]

Dubious information:

Well, if it goes up and down with the same apparent speed as the engine (1500 rpm - 5000 rpm) I'd say you can rule out the accessories section.  Your fuel pump, vacuum pump, your hydraulic pumps, your magnetos, and even your prop governor all should be turning  a lot slower than the engine speed.  So that part is good.  

If you mains were bad, the engine would have likely blown itself to bits by now.  So that's probably good too.  

Now my advice is not likely to be acknowledged by anyone here, but if you approach machines anyway like my friend does - just turn the radio up louder...

I can't even figure out why older posts keep showing up as new messages.

[nhmaf]

I'm still betting on either throwout bearing/pushrod, or  possibly the diaphragm spring/clutch assembly is out of spec.   In any case - if it is liek that youtube sound, it certainly sounds like dry metallic rubbing, which is certainly not a good thing in most cases.

the pitch does change when you rev up the engine?
Have you pulled the drain plug on the transmission yet to look for metallic shavings?

[John M]

I think the answer to my noise is the clutch throwout bearing,I have just pulled the transmission for an overhaul with circlip install and taller fifth gear and the clutch push-rod seemed to be bound to the front half of the throwout bearing so it was spinning in the bore. Thanks to every one for your diagnostics, you pointed me in the right direction.
     Best Regards  John    ( You nailed it Nhmaf )

[John M]

I just went over the posts and want to include Monte and Wirespokes
in my thanks in addition to Nhmaf you all are batting 1000
                             Best Regards John

[tvrla]

I don't quite follow you on what the problem was. The throw-out rod is attached to the center race of the bearing. The bearing should spin in the piston.

Are you saying the bearing is frozen and turns the piston when the rod is rotated?

IF that's the case, hopefully the bore in the transmission cover wasn't damaged.