It can also be a slightly high idle/throttle linkage stop setting. Try backing the idle adjuster off a little (get the idle down to about 1100rpm) to see if it helps.

where is this idle adjuster? can someone direct me to a idle adjust how-to or a page # on the web manual?

*edit* nevermind...found it:
http://www.nsr250.net/forums/members/web_manual_mc18_21/titanium/index.php