superpimp

Hi guys and gals, Need help.My thundercat as and RPM issue.And goes up to 8000 when on neutral then goes back down to zero and goes back up and again this during the entire time im riding.Seems like a bad conection or something can anyone tell me where is the RPM sensor or cable on the bike so i can find it and test it out.Ive looked but cant find where it plugs in the motor. Thanks for infos Dan