2006-2009 Honda TRX250EX/TRX250X Service Manual, Page 105Get this manual
FUEL SYSTEM Start the engine and warm it upAdjust the idle speed at high altitude with the throttle stop screw to ensure proper high altitude operationtOLE SPEED: 1,400 100 rpm (min-' )
When the carburetor has been modified (or high altitude operation, the air-fuel mixture will be too lean (or low altitude useOperation at altitudes below 5,000 h(1,500 mJ with modified ca rburetor may cause the engine overheat, resulting in serious engine damage and increased exhaust emissionsFor use at low altitudes, you should return the car buretor to original factory specificationsReplace the main jet with the st andard main jet, and screw out th pilot screw the specified number of turns from the high altitude settingSTANDARD MAIN JET: 195 LOW ALTITUDE PILOT SCREW OPENING118 turns out from the high altit ude setting TOOLS: Pilot screw wrench (0 type)