Gearbox additives

[ukzknos]

I know you regulars will have read before about my whinging over the 'screech' at 2000rpm from my bike but I still haven't fixed it and it still annoys the hell out of me.
I've come to the conclusion that it IS coming from the gearbox but before thinking about a gearbox rebuild, and as a recon box is beyond financial rationale, has anyone any experience or views on the various additives available; molykote, slick50, etc?
 
Steve

[montmil]

Steve, Have you tried a stethoscope against the gearbox? I picked up an automotive-style 'scope for cheaps. Very useful diagnostic tool.

My "big end bearing failing and screeching" turned out to be the cam chain's tensioner and guide!

After Lord knows how many miles on the old chain, it had gone a bit slacker, then proceeded to carve "notches" in the hard plastic guide surfaces. Made a screeching noise that sounded like, well, bearings failing. Motobins is the place. All good now.

My  [smiley=2cents.gif]   Monte

[ukzknos]

Good advice Monte but problem is I couldn't use it while riding. The other issue in trying to pinpoint the source is trying to hold the revs bang on 2k to sustain the noise long enough to make a judgement on where it is.
I think it's a major gearbox build next winter!

[Bob_Roller]

Have you removed the magnetic drain plug from the transmission ?

If you haven't drained the transmission oil, might be a good idea to do it, and look at the drain pan for signs if excessive metal content .

That should tell you if you have a real problem with bearings and other internal problems, by the amount of metal on the plug .

As far as an additive is concerned, if the price isn't to high, it won't hurt anything, but I wouldn't expect a 'miracle cure' from it .

[79r65]

If your bike is using points, I read where if the cam shaft is dry, the points arm will make a screeching sound...  Just a thought.

[ukzknos]

Nash_B

That's an interesting thought because I am still running on points but I don't quite understand it as the camshaft is constantly lubed by the engine's oil system.
If you could find the article I would be keen to read.

[steve hawkins]

Barring imminent self destruction of bearings, I'd be looking at an area on you bike where things can dry out.  Oil in the gearbox should stop screeching and so should oil in the engine unless they are in serious trouble.

Assuming your driveshaft, etc, have oil in them, then it only leaves the clutch mechanism and perhaps under the front of the engine cover (alternator, bean can, etc).  But since you have to be moving I would be pulling the gearbox and looking at my clutch.

If you drop your oil in the engine and gearbox and all is well on the iron filings front, then I would be looking at the areas mentioned above.  Gearbox additives wont fix a screech.

The other thing is, what have you dusturbed recently and was the noise there before you started?  Or has the bike been stood for a very long time?

[ukzknos]

Good thoughts Steve,

I picked up the bike in March this year and other than the guy getting it running to sell it had been stood for several years.
Meanwhile, I have new fluids in everything possible and no metal debris was found during the changes.
The screech is definately a 'dry' noise so maybe the clutch is the area to focus on.
The other thing that springs to mind is that it happens at 2krpm in all gears and so does suggest some 'out of balance' problem; clutch/flywheel?

[Ed Miller]

Nash_B

That's an interesting thought because I am still running on points but I don't quite understand it as the camshaft is constantly lubed by the engine's oil system.
If you could find the article I would be keen to read.

He means your points cam, the little cam that pushes the points open.  THAT should definitely not be constantly lubed by the engine's oil system!  

[ukzknos]

Oh, the points cam, lol  

I don't think a noisy points cam would scare the pedestrians like this screech does!