I have a '92 warrior 350. The warrior won't start, I test the battery and it is running at full voltage. When I start the ignition it drains the battery down to four volts. I've tested from the starter motor to ground and there is a dead short. There is also a dead short present from positive battery terminal to ground at all times. I pulled the starter out and there was no sign that it was seized. I also tested the solenoid and it is fully operational. I can however jumpstart the quad with another batttery. Would this be a result of the starter motor shorting out?

 

so if you change the battery source it starts fine? sounds like you have a bad battery