Hi Ihave a leak primary gasket on the left hand side .Do i need to mess about with the clutch can i just unbolt the cover change the gasket bolt n go

You don't really need to mess around with the clutch, per se, but you will need to losen the primary chain tensioner and drain all the fluid. If you want to take the cover completely off, you'll need to disconnect the clutch cable. You shouldn't have to do anything to the clutch though. I'm just going on what I know from my 93 XL, different year models might be significantly different for all I know. There is also a torqing proceedure for reinstallation too, I think.

While you have it off (and xlch ice did a good job describing that process), you might as well adjust the clutch. You'll have to re-adjust your clutch cable anyway too. Might as well do it all while you are in there. Also, if you have a pre-04, make sure you get the redesigned gasket with the metal core. You'll neeed the service manual too.