Oil leak

[Phil C]

If there is a chain oiler fitted, would it be visible  without taking off the primary chaincase cover?   Phil.

[JulianS]

Yes.

Look at rear of primary case if it is still fitted it is attached by one of the rear screws from outside, I think the centre one. If not fitted the orifice should be selaed with nut and fibre washer.

The photo shows one I removed from a 1961 B40 many years ago.

[Phil C]

Just had a look and yes, I've got one. But that couldn't be the source of my oil leak, could it?   Phil.

[Phil C]

This seems a bit odd to me.  When I take out the drain hole bolt on the primary chaincase, oil runs not only from the drain hole but also from a point in line with that but inboard of it, inboard of the mating surface of the casing.  I can't quite see where it's coming from. Any ideas please?   Phil.

[JulianS]

Check if the hole for the drain screw goes right through the case - push a bit of thin wire in does it come out the other end? If yes thats where the oil is coming out inboard.

As for the leak - you could remove the oiler and seal the hole with a 1/4 x 26 tpi nut and suitable fibre washer. It will do no harm.

But for the main leak you do need to look inside the primary and remove the clutch. Could be the gasket leaking between the oil seal housing and chaincase and/or the oil seal which bears on the extended bush coming from the gearbox sleeve pinion. This has already been suggested by Thumper. The extended bush, if a phosphor, suffers from wear from the seal and often has a groove worn in it causing a leak.

Do you have the Rupert Ratio Unit Single engine manual? If not it is invaluable packed with information and worth every penny.

http://www.ratiopublishing.co.uk/

When you buy an old bike part of the deal is that you get some special tools (clutch puller most important) and try the jobs. Everyone had to start somewhere. You dont need a fancy workshop or large garage (though it does help) just some basic facilities, a good set of tools, common sense, drive and enthusiasm.

[AWJDThumper]

In order to confirm whether it's chaincase or gearbox oil that's giving you the main leak, you could try draining the chaincase and then taking the bike for a ride. The lack of chaincase oil shouldn't be a problem. If you still get the leak afterwards, it points to it being a gearbox leak and the clutch will definitely need to be removed.

[Phil C]

Thanks AWJDT, but I've already taken off the chaincase cover and removed the clutch plates, so I might as well carry on.  I'm waiting for the extractor tool to arrive in the post (hopefully tomorrow), but meanwhile I guess I will now need to remove the large nut in the centre of the clutch, jamming a piece of wood or something against the chainwheel to prevent it turning? 

Will I need to remove the chainwheel, alternator, and crank sprocket?   

Phil.

[AWJDThumper]

If the rear chain is still on, put the engine in gear and lock the back wheel. Unfortunately, you'll also need to remove the alternator, rotor and engine sprocket. The clutch can only be removed at the same time as the engine sprocket because of the duplex primary chain which can't be split. If you've taken the clutch plates out, you'll need a clutch locking plate before you can undo the crankshaft nut holding the rotor and engine sprocket on. Otherwise, put the plates back in and with the gearbox sprocket locked, you should be able to undo the crankshaft nut.

[Phil C]

Thanks again AWJDT.  Will I need any kind of puller for the engine sprocket?  Phil.

[AWJDThumper]

If necessary, you can always carefully lever it off.

[Dabbist]

Just a thought, before doing that much work. Could it be that if youve topped up the chain case oil enough to increase the amount coming out of the chain oiler, the chain/sprocket could be carrying it over and chucking it down that part of the case.  Maybe worth making sure that's blocked off first?  Even shoving some blue tak  up it might work for a quick test, since there's no real pressure involved.

[Dabbist]

Sorry... I missed page 2 of answers    just ignore me.

[Phil C]

Me again. Trying to undo the clutch centre nut, and can't get it to budge.   Working on my own, except occasionally for wife who is willing but not very strong. Tried holding the back wheel while she heaves on socket wrench, but no good.  Tried jamming a piece of wood between rear sprocket and floor, but the whole back end of the bike moves before the nut will undo.  Any tips please?  (Not a left-hand thread by any chance, is it?)   Phil.

[JulianS]

Right hand thread.

Sometimes a hard sharp tap on the socket wrench with a suitable hammer will start it.

[Phil C]

Yes, thanks Julian, I'd tried that but without success. However, I just got my neighbour to help me:  whilst I pushed hard down on the back brake and wielded the spanner, he sat on the bike to stop it moving around, and...bingo!   Thanks again anyway.   Phil.