8-9
ESS58401
HIGH ALTITUDE ADJUSTMENTS
Operating at high altitude reduces the performance of a
gasoline engine, about 3% for every 305 m (1000 ft) of
elevation. This is because there is less air as altitude
increases. Less air means less oxygen available for com-
bustion.
Your snowmobile can be adjusted to overcome most of the
problems found in high altitude riding. Carburetor adjust-
ments are the most important. Less air at high altitude
makes the fuel/air ratio too rich, which can cause poor
performance. Common problems are hard starting, bog-
ging, and plug fouling. Follow the Main Jet Setting chart
which is available at an authorized Yamaha dealer care-
fully. Proper carburetion adjustments will correct the fuel/
air ratio.
Remember: less air at higher altitude means there is less
horsepower available, even with proper carburetion. Ex-
pect acceleration and top speed to be reduced at higher
altitudes.
To overcome operating with less power at high altitudes,
your snowmobile may also require different clutch and
driveline settings to avoid poor performance and rapid
wear. If you plan to operate your snowmobile at an altitude
different from the area where you bought your machine, be
sure to consult your Yamaha dealer. He can tell you if there
are any changes necessary for the altitude where you plan
to ride.
CAUTION:
The drive chain gears and V-belt clutch should be
adjusted when operating over 900 m (3000 ft) high
altitude. Consult a Yamaha dealer.
