2004-2005 Honda TRX450R Factory Sevice Manual, Page 34Get this manual
TECHNICAL FEATURES
HOT START SYSTEM
Tho hot 51art ,yo,em creates" lean airlfuel mixture that enables hoi "naine to be Slarled easily, WI'en 'he hO'-SI",tleve, ilocaled on the lefl side or the hondlebor) is "LJShco "Way from rider, the hot "'ort valve In the corburctor opens, sup air to the main bare threugh the hot start air pa"aue, This exlra ai, blends wilh the a;rfuel mi,ture from the slow circ"it os"lting in" loun oonditienHOT START VALVE
-t:, HOT START AIR PASSAGE
MAIN BORE'' -::::::::::-