Speedometer Reading Incorrect
 

My son has a 2003 Suzuki GSXR 750 that the sppedometer doesn't display the proper speed. We have done a test of the speed sensor, tested ok. Also we have verified that the front and rear sprockets are correct 17 teeth front and 42 rear.
Has anyone had a similar problem and what did you end up doing to fix it.
The inside end of the sensor that is next to the speed rotor is worn slightly, not supposed to be that close I have been told. Makes me wonder if the front sprocket could have been installed backwards. Would it be possible for this to happen?? I am going to try and shim the Sensor out from the rotor by putting a washer on the backside of the sensor fastening allen screw.

Any other advise would be appreciated.

Hello, few questions for you to answer