High Altitude Carburetor Adjustment - Honda TRX250TE 2019 Owner's Manual

Your engine's air-fuel mixture becomes overly rich when operated at
high altitudes. Above 1,000 m (3,000 feet), a rich mixture can cause
driveability problems, reduce engine performance, and increase fuel
consumption. To compensate, you can have the carburetor adjusted
for high altitude riding. See your dealer.
A high altitude jet is available to compensate for high altitude
richness. For those who are mechanically proficient and have the
necessary tools, installation and adjustment procedures are given in
the official Honda Shop Manual available from your dealer. All
others should have this carburetor modification performed by your
dealer.
However, the carburetor must be returned to standard factory
specifications before riding again at lower altitudes (below 1,500 m,
5,000 feet).
Sustained riding at lower altitudes with the lean high-altitude setting
may cause rough idling, stalling, or engine damage from
overheating.
Altitude range
0 – 1,500 m
(0 – 5,000 feet)
1,000 – 2,500 m
(3,000 – 8,000 feet)
or higher
High Altitude Carburetor
Main jet Pilot screw
Factory preset
No. 98 Screw in 1/4 turn
clockwise from
factory preset
Adjustment
Throttle stop screw
Factory preset
Screw in 1/4 turn
clockwise from
factory preset
Technical Information
209