Mine had exact same symptoms as you described, this progressed with time to the point when it was not road worthy. Turned out to be a loose clutch basket nut. I also found some other damage - see
this topic for full story if interested.
I have replaced clutch, engine oil (obviously) and I know everything is within specs, torqued properly and in good shape. Clutch still drags a little bit (bikes not moving really but I can feel it wants to if you know what I mean) and I've tried both OEM and aftermarket slaves. I guess it's one of them things that you just need to live with
When mine's cold, it ocassionally stalls when put in 1st, but that's because my idle is set very low (1000 rpm) and as cold engine oil is more viscous, engine dies cos it can't spin with that much resistance on low rpm. It's fine on 1200 rpm (with fast idler lever).
If you still think there is an isuue, pull your clutch. It's easy. You don't need any special tools to inspect it as you don't need to take the clutch basket off!
- get manual, it gives you correct specs and check list
- check clutch pack stack height and all individual plates (warpage, thickness, colour; see manual)
- check the 6 big springs and 3 small ones under the pressure plate (again, refer to manual for specs)
- inspect and grease pushrod (maybe it's bent?), replace orings (they're like £2.50 so just do it)
- check throw out bearing
- check if there are any notches on clutch hub or inner basket, or any obvious damage; if you find something, I would remove the basket and check damper springs in the back of primary driven gear - yes in this case you'll need to buy/fabricate a tool but it's worth doing it as broken springs can cause catastrophic damage
then put it back together and make sure everything is torqued properly
