Hey guys just bought a Baja 90cc quad. When I unplug the tether the quad starts right up and keeps spinning the starter. I ended up putting a new harness in so maybe I did something wrong? Any help will do

 

Yes, you did something wrong. Disconnect the thin wires to the starter solenoid and see if the problem goes away. If it does, one of those thin wires is connected to something it shouldn't be, as is the "tether" wire. Trace them back.