I recently bought a 02 grizzly 660 with lots of mods. Anyways the speedometer comes on and shows a full display but does not track speed or track miles, just remains on 0 mph. Only thing I can add is that every now and then I will turn the key and there's no display but after a few taps on the fuse box the display comes back on. Thanks in advance for the help

 

Remove all the fuses, clean them, and the fuse block as well, and add dielectric grease. Then try it again. The ATV pictured has been set up for deep water/mudding, may have many dirty connectors that require cleaning.

 

My guess would be the sender unit for the speedo gone wrong, or the wires from it. No idea where it is on a 660.