BRAKE NOW WORKS............. got it back home today from the bike shop. the mechanic could not fix it.
took it all apart including the seals and pistons ang gave it a good clean.(was not that dirty though)
rebuilt it and filled master cylinder, craked open bleed nipple and let it bleed with gravity. after sbout 3hrs of this and some normal pressure bleeding there was still NO pressure on the lever.
i gave up trying and had a fag. bike had not been started for about 3 weeks, so i kicked her over and revved for a few minutes.
ipulled the brake lever one more time........and felt pressure which built up each time i pulled it.
now brake works better than ever....the vibrations from the engine revving must have freed some air from somewhere..i think??
anyway it works now. THANKS FOR ALL THE REPLYS, GREAT HELP, CHEERS ALL ROB X