Is it not starting at all? If there's a problem with the neutral switch it should still start with the clutch pulled in so you can try that as a quick test. Have you got a multimeter? As punk said there could be an issue on the positive of the control side of the relay which is the Red/Black wire. You should have battery voltage on the Red/Black wire at the relay with the ignition on. You can test that by connecting the red lead of your multimeter to the Red/Black wire and the black lead to any ground. You should see 12V with the ignition on. If you don't then it could be a problem with the Red/Black wire itself like corrosion or a break, or it could be a problem in the kill switch on the handlebar or the ignition fuse, the ignition, the main fuse or the terminal could be loose on the battery. If you do have 12V at that Red/Black you can test the relay itself. There's a procedure on page 8-16 of the workshop manual. You take the relay out and connect the + side of the battery to red/black terminal on the relay and the - side of the battery to the black/yellow terminal and test for continuity between black/white terminal and black terminal. There's a wiring diagram on the last page of the workshop manual. Item 9 is the relay