Hot weather whirring or droning noise?

Hi there, I've noticed a strange whirring/droning noise underneath the main engine sound. It seems to exert a very slight braking effect also. About 2 drones per second.

I was wondering if it's the water pump, given the heat. Also, I've been running pure distilled water rather than pink coolant, as I'm in spain and don't know if the correct coolant is available. Perhaps I've gone and knackered something?

Cheers chaps, happy riding

I should add, the whirr happens when I'm coasting down hill engine off. It gets faster the faster I go. Honestly no bloody idea! Thanks a lot

... also there is no whirr when I sit stationary and rev... so ok it must be some system I am ignorant of... Thanks guys.

fgclark123 wrote:I should add,  the whirr happens when I'm coasting down hill engine off.  It gets faster the faster I go.  Honestly no bloody idea! Thanks a lot

It's your chain/sprockets, or, at least, something in that area. Don't know what exactly, but, when you are coasting downhill, the drive is 'in the wrong direction' for the wear on the chain/sprockets (i.e. rear wheel is leading/pushing the engine, rather than the more usual situation where the engine is pulling the rear wheel).

I'm not entirely surprised it makes a slight rattling/whir/noise. If it is only when coasting downhill the I wouldn't worry.

The only significant problem that distilled water will cause is your coolant boiling! Distilled water boils at 100 degress, whereas all/any suitable coolant mix for the CB500 boils at a higher figure (108 or so).

The CB500 doesn't require any particularly special type of coolant AFAIK; as long as it is suitable for aluminium engines and suitably diluted it should be fine. I've quite happily used the blue stuff from Halfords without a problem.

Yes you're right - it was the bearings, absolute mess. I carro ed a pillion for a couple of days, could've been that.currently on a spanish workshop putting it right under breakdown insurance. Fingers crossed should be back on the road soon.

Cheers though thanks very much. Live and learn...

Which bearing was it? I've been through a few sprocket carrier bearings; seems to eat them at a fair rate! Luckily they are not expensive or difficult to fit.

Hi there, unsure of the name, but here's a pic.



Do you have a seller you'd recommend? I'd like to have a few on hand for touring situations. thanks

Looks like a previous owner wanted to save a couple of pence.  Should be sealed bearings to keep the grease in and the dirt out also they last a lot longer.

James has a post with original Koyo part numbers here Bearings and Seals

Once you've found the bearing number go HERE for current Koyo number and alternative makers, NSK and SKF.

As for a seller, to quote James from another post "You want NSK bearings, have a look at simplybearings.co.uk"

great thanks. I think the stock replacement is already whirring to itself, may need these soon. cheers

That's a wheel bearing; you might as well replace the one on the other side as well.

If you pull the sprocket carrier out of the rear wheel/cush-drive then the sprocket carrier bearing is the one that is in the sprocket carrier.

aditives in coolant liquid help pump etc.
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