Removal of the inner gearbox cover on a 750 (1972)

Hi all,
I want to inspect the gearbox mainshaft and layshaft,hopefully not to strip it.I have no idea of the internal condition as the bike was purchased as a bike needing recommissioning.I need to take the gearbox inner off to replace the trunnion roller,which does show signs of chipping.My question is,do I need to disturb the mainshaft securing nut to take this cover off.I want to disturb as little as possible,and to just visually check the internals.I realise this has been covered before but I cant find a definitive answer on whether the nut on the mainshaft really needs removing.

Yes the nut which is behind the clutch operating mechanism need to be undone, anything more than inspection will require the removal of the clutch from the main shaft.

Just to clarify, you can remove all of the gearbox internals except the sleeve gear, main shaft and associated bearing without removing the clutch, drive chain or gearbox shell from the cradle.

So if I remove the mainshaft nut under the clutch lever mechanism along with the 7 nuts,when I attempt to seperate the inner cover,would this then come away with the mainshaft bearing intact inside the cover?

Shadowcat said:

would this then come away with the mainshaft bearing intact inside the cover?

Click to expand...

It stays in the cover as the flange it sits against faces the gearbox.

When the cover is drifted of (hopefully) does this normally have any detrimental effect to the bearing.I,m trying to minimise the amount of work which I may,or may not have to do.Like I said the roller trunnion needs replacing anyway.I,m hoping the covers will seperate because the PO certainly had a fondness for clear silicone,and the external and internal faces need to be seen to be believed.
I just wonder why anyone would resort to using such copious amounts of silicone and not cleaning up the excess.Any obvious things I should be aware off.

The bearing is cheap so worth replacing but if you are planning to do the work and can't wait for an order to arrive then once the covers off spin the bearing inner and listen for any roughness, if it spins quietly then reuse.

'I just wonder why anyone would resort to using such copious amounts of silicone and not cleaning up the excess. Any obvious things I should be aware off.'
Be aware this is a 54 year old bike, with probably a few 'previous owners'.. And whilst most old bikes now lead a spoiled life with knowledgeable owners, it might not always have been the case.
Roadside repairs, dubious pattern parts and the misuse of tools can prompt bad practices (levering cases apart with chisels, screwdrivers etc.) that your 'copious amounts of silicone' might be attempting to cover up...
Nothing a healthy bank balance can't cure! .-)