i have the same problem with my 2000 fourtrax es. Its something to do with the starter. I havent bothered to fix it, I just use the pull cord.
This is the first thing to check.There's a good chance your battery is bad , after you run it for a little while it puts a charge on the battery enough to start it, but cant hold a charge for long, you can try charging your battery with a charger but i bet the battery is shot
Good point! I have had issues that were little more than a corroded contact.Remove and Clean the battery cables and battery terminals. Clean the cables attaching to the solenoid too, along with the ground cable attaching to the motor. Clean the cable attaching to the starter motor as well Have the battery load tested (and replace if weak) if clean cables don't solve the problem. You can test the solenoid while cleaning the cables.