I have a 2000 450 ES when i am riding and get upto to about 40 k it locks in whatever gear it is in , and then have to shut it down and start all over until i hit 40km again any advice anyone,people are telling me the angle sensor but i tryed on and it made no difference

 

You could try checking the clutch adjustment. It is on the front engine case it a flat blade in the middle and 14mm nut. loosin the nut well holding the flat blade inner than back the screw out til you feel tension than go clockwise a quater turn that will set the clutch free play.