Stiff clutch

Clutch adjustment has kind of been done to death so reading previous discussions and deciding which works for your case is the best approach.

The thicker steel plates are used to replace one of the originals so as to increase the stack height as desired and move the engagement point along the spring pressure curve.

As for the effort required to operate the clutch, it depends what you're comparing against: a Jota or a CBR600 :)
The clutch will be initially heavy and then 'snap-over' as the diaphragm spring does its thing. You can play around with the adjuster screw in the clutch to find a position that works for you - it's a 20tpi thread so one full turn equates to 1.27mm - and add/remove steel plates to get somewhere close

Your next problem is likely be clutch slip - also covered extensively here.

Are the plates bronze and have you screwed out adjuster by a whole turn, as in Haynes? I experience a lever action with a hump but in use it's not tiring.

In its original form it is a good clutch but there are so many variables, all mysteriously interconnected, and that needs forensic attention to info gathering. As it turns out I need to revisit oil pressure, the shims in the oil pressure relief valve (maybe not ness with a new spring with better tolerance?!) as the primary gets engine oil leaking from the crank oil seal, and the clutch likes 200ml of oil but not a lot more. Who knew? Sent me down a clutch/gear selection rabbit hole.

Thats why I asked if its standard as so much advice seems tailored to mods which is why I forgot Haynes for a year and had guru's turn back the adjuster by a quater, a half turn ..and there was no 'hump' but drag and slip and a gearbox issue, all not applicable! I even have a pushrod seal for (no) leaking gear oil which I'll fit one day for the hell of it. Also carry a magnet in tool kit to retrieve that adjuster nut from the primary via the inspection cap when it shakes loose on first long motorway run, that fix really impresses modern bikers done on the hard shoulder.

Your pressure relief valve has nothing to do with engine oil getting into the primary case, Your crankshaft oil seal is knackered.

Peter F.,

if you have the clutch cable secured too tightly to the frame tubes with cable ties or whatever, then that can also cause a stiff clutch lever operation.

Allow the clutch cable to flex freely and try the clutch operation again. 
 

Hope this helps.

The answer - The first thing to determine is what pressure plate you have as that dictates how many clutch are plates needed. 

Thin pressure plate  = 5 friction, 4 plain
Thick pressure plate = 4 Friction, 3 plain. 

In either system many found that substituting a plain steel plate with a 3mm plate will lighten the clutch. It is a substitution and not a stuffer plate. 

The above has known fail, but it is usually an 850 where the sintered plates have been replaced with old Barnett plates, the original Barnett 850 plates where undersize up until 4 years ago or so, they are now all the correct thickness and work very well even if contaminated. 

Sounds simple, it really is, but every month the workshop see bikes with a mix of plates various. 

Its an easy fix trying out thicker metal clutch plates so I would try that first. I could not believe how much easier it was to pull my clutch in after fitting a thicker plate. Get a 3mm and a 4mm from RGM for about £7 or £8 each plus VAT and postage. That way you can increase stack height by 1,2 or 3mm as the standard ones are about 2mm.
if you can just get the large circlip in the groove to hold the diaphram spring in place then that should hopefully do it. Just check at different rpm and speeds that the clutch is not slipping. While the plates are out give them a wash in petrol and let them dry. Once dry rub them on wet & dry or Sandpaper on a flat surface to remove any glaze on the fibre plates. Hopefully your clutch is standard like my 1972 750.

Hi Peter,

Are you aware that the oil seal can easily be pushed in too far? The attached picture shows one removed from a leaky bike. It is sat atop the special insertion tool that pushes it in exactly the right amount. You can see where the crankshaft has eaten into the oil seal.
Once pushed in too far, it cannot be pulled back out again without causing damage.

Regards

Tony

If the cam on the lever, in the gearbox inner cover, is worn, it will make the clutch hard to pull in.

Fuel in the primary can explode and fracture the case.