Well, according to the '04 Owners manual it says the proper play is 2-3mm
Not sure if mine is that tight, so maybe I should adjust it too...
Instructions in the manual are:
-Loosen the locknut at the clutch lever.
-Turn the adjuster so that the clutch lever will have the specified free play.
Looks like the locknut and adjusters are on the back side of the left grip following the cable from the end of the actual lever. the locknut is the larger of the two and at least on the '04 they aren't hex bolts... no idea on the amount of torque to keep them in place.
Also has a warning to make sure you keep the cable and assmbly together or you could lose control of the clutch if you ride like that.
-Tighten the locknut.
-If it cannot be done, use the mounting nuts at the lower end of the cable.
Which is referring to where the cable connects to the actual transmission and you have two hex nuts. Supposively that's self explanitory as it doesn't have the lock or adjuster nut labeled.
There's also a side note saying fine adjustments should be done at the lever.
Also, I've heard from many experienced 250 riders that the clutch noise is normal, don't worry about it. The bike will not explode, nor is anything greviously wrong. If the clutch starts to malfunction you should worry, but not about the noise. Info comes from
http://www.ninja250.com/ You can look thru the forums and FAQ's for a plethora of information.
Well, hopefully some of that was of use...