what is your bike doing/not doing?
if our bikes are anything like the earlier gsxrs ('04 750 is what I am referencing here).
There is a disc that goes on your front sprocket. this disk is what tells your speedo sensor how fast your bike is going. i am at work right now, or i would find it for you....there are links all over the interwebs to dowloads of the shop manual for our bikes. go there and check them out or you can call your dealer and they can tell you. as far as price for that 'disk'...it was cheap for my 750, about 14 bucks. the speed sensor was about $95.
hope this helps