Just a random thought. Some models later than your have an adjustment in the pressure plate, but wouldn't have it on the left on the arm--just a locating screw with built in pin. Not an off center pin to lift the arm.
Rethinking the arm angle--i think--just shorten the cable & have the arm as far back as lifting the arm with adjuster will go. Does it feel ok lifting the clutch with pliers by turning it.

i tried a 4 mm ball and it is too much. should the mushroom rod be flush in the shaft or stick out a bit ? mine is flush when i start to turn the actuator arm the mushroom starts to move imeidiatly just dont feel resistance .should there be a spacer on the cable before it goes into the cable guide on the crank case ? is there an easy way to remove the rod to measure it etc ?

I'd better tread carefully as not familiar with those & only going by pics.
But--the mushroom movement depends on clearance before it touches the pressure plate to start lifting. If you mover the arm until it touched the pressure plate, then removed the plate you'd find the mushroom sitting away from the shaft by a little.
I think just carry on & space up the cable if you can't soften the solder & move the nipple up a bit & re-solder. I make my own cables.
I'd be interested to know if the long rod will fall out if you lean the bike over to the right. My guess is it won't, so fatter rod than the mushroom & rounded end--hence no ball used.
Can you find a slotted lever adjuster & slide over the cable at the lower end to take up some play.

Did the clutch work before you installed a new cable?

What else have you done? Maybe the disc stack is too tall?

think he baught the bike without a cable

Thanks RT325...  it's hard to know what's been done...  If pushrod moves when lever is turned I guess it could be adjustment or someone could have messed with clutch itself?

i have completely rebuilt the engine as it was in a bit of a mess from water ingress . new crank ,clutch ,bearings etc . there was no cable on the clutch when i got her... 

Blimey, sure was a mess & well done 'you' rebuilding it. look forward to the next chapter & hope all goes well. did you get a good crank or clean up & rebuild that one with new rod kit.
Does your model have the advance arm & cam magneto flywheel. If so, i hope that is ok & not total rust.

mushroom rod is about 62mm long . i need to get the other rod out to measure that ?? any ideas ?

Leave those rubber rings out while ya in there. They serve no usefull purpose--just saying.
Also, [think i mentioned in earlier post] i suspecting the long rod only come out [& goes in] from the left as is a bigger diameter so gotta remember to fit it before assembling the cases.
Have you 'got a problem. or maybe just think you do. I hope you havent. Is the main shaft sitting too far to the right. If it was i'd think the primary gears [clutch & crank] would be out of alignment by an obvious amount.
Is the fat rod bumping the step down size in the shaft & running out of lifting travel [not heard of that before].
Gotta be an answer as can't add a ball against a round ended [curved ended rod].
I gather you must have a slined pressure plate? otherwise you'd have a steel in there last.
Can we see a pic of the pressure plate please [no adjuster in it?].
How about refitting the pressure plate then take a pic of the arm where it starts lifting. Then lift the clutch & get a pic of the pressure plate at max lift & also how far the arm ends up at when clutch lifted. Keeping in mind you might be moving it further by turning with pliers/wrench etc than how far it moves by handlebar lever. So try to simulate 'that' travel.
Is it possible the clutch hub complete with plates is sitting out too far. I can see room down the end like it could be back further, but then again the center nut looks ok & on fully as it should be.
Sorry if that reads confusing--i know what i mean if no-one else does.