The speedo has a batt backup that eventually looses contact which can lead to the speedo resetting mileage as well as time. If your odometer is NOT resetting when the time does, I would pull the connector in the headlight bucket, spray with alcohol or contact cleaner, then a little dab of dielectric grease and reconnect. Also chEck your terminals that they're clean and retighten using star washers. That's a starting point.
2011 White Vision - Nuvi 550, Lowers, Lloydz 2nd filter, Vic perf filter, CB/Icom, 96 Brake LED's, Clear Signal lens/Switchbacks, VIC Hwy Pegs, Stebel Horn, 7Jurock 15" Shield, PCV, Lloyd ATS and Variable intake, Ness honkers
2004 V92 TC - S1 flash, level 1 slip-on, Ness big sucker K&N, ISO Grips, 4x1.5 Highway Hawg Risers, extra chrome (never too much), JM 2k CB 4' antena, Mustang seat, HD Front TS & Lowers, OD Pulley
Retired Navy SCPO