a common problem.
I modded mine a bit:

removed the original screw and replaced it with a longer one, before put a nut next to the head.
Then inserted the new screw and tightend the lever with the nut.
Never got loose again.

BTW: I'm using this one:
http://www.off-the-road.de/de/XT-660...r-einfach.html

salu2,
Joe

__________________
Saludos,
Joe
http://web538.ypsilon.ibone.ch/index...d=89&Itemid=42

neoprene fork protectors Acerbis / blue Puig wind shield / fork spacers 24mm / snorkel and resonater out / Acerbis hand protectors / 25 mm bar risers / 12 V outlet / "soft throttel mod" / engine protector home made / PC III USB / DNA ST2 / K&N ST 1 / BSM "Future extreme" exhaust / Wilbers "Adjustline" Shock / XTX links / luggage carrier home made / automatic chain oiler home made