Since I've removed the gearbox, I can lubricate the end of the gearbox input shaft and the corresponding splines on the clutch friction plate. However, I'm not sure whether I should also take the clutch housing off the engine output shaft and lubricate those splines also. I'm wondering if this is something you're meant to do as part of routine maintenance. Any help would be appreciated.

Just the gearbox spline and clutch plate spline need to be done but as you put it back together remember to put some lube on the end of the clutch pushrod where it goes into the rear of the engine output shaft and the diaphram spring.

I would suggest also now that you are in there to replace the rear main seal as well as the O ring behind the centre nut. They're getting old and hard unless you know they have been done in the last few years.
To do this you need to remove the clutch carrier but dont need ti lube those splines as they are in the oil bath of the sump.

If you do decide to do this ask and I will give you some hints on making it easy.

HINT put your model and year in your signature line so all know which bike you are asking about.

JonnyE wrote:Since I've removed the gearbox, I can lubricate the end of the gearbox input shaft and the corresponding splines on the clutch friction plate...Any help would be appreciated.

Of course, during reinstallation of the whole lot would be a good time to do the gearbox output shaft splines as well as the final drive input/driveshaft splines...

Yeah, that 'what bike are you talking about' issue comes up with more frequency as more and more new members join us. It is easy to include this basic piece of essential information in the signature line of your profile. For this particular job they're practically all the same, but still...

Ok thanks - On refitting I will also lube the splines on the final drive shaft, the gearbox output shaft and the final drive input. Rick mentioned the rear main seal: I think you're talking about the seal which you would see on the end of the output shaft, with the clutch removed. Is this relatively easy to replace? I'm not sure how you would get it out. Thanks.

To get to the main sfaft seal you need to remove the big aluminium disc (clutch carrier) the clutch bolts to.
Remove the clutch taking care to mark the three bits for relative position to each other so you know how to put it back as it was.
Clean the head of the 6 sockethead bolts so as to get a good grip and a small bit of heat from a butane torch helps overcome the thread lock.
Remove the big 32mm nut at the center and then get the Oring out from behind the nut. It is difficult, I skewer it with a point and then cut it into bits to get it out.
The clutch carrier wont come off till you get the O ring out. remove the carrier and the seal is there in front of you.
The OEM seals are best but aftermarket are available but must be Viton type to take the heat.
A slide hammer with a hook gets the seal out.

Rick, thanks for your clear explanation - I'll give it a go.