Yamaha Vector RS90RX, Owner'S Manual

Page: 52 / 90

Periodic maintenance
46
12. Install the headlight unit bolts, and then
tighten them to the specified torque.
13. Place the wire harness in the original po-
sition, and then fasten the plastic band
around it.
14. Install the top cover, the right side cover,
the left side cover, and the shroud.
NOTE:
After riding the snowmobile, make sure that
there is no snow under the air filter element
frame.
ESU11910
Carburetors
The carburetors are an important part of the
engine and its emission control system, which
require very sophisticated adjustment. There-
fore, carburetor adjustments should be left to
a Yamaha dealer, who has the necessary pro-
fessional knowledge and experience.
ESU11940
High-altitude settings
Operating at high altitude reduces the perfor-
mance of a gasoline engine about 3% for ev-
ery 305 m (1000 ft) of elevation. This is
because there is less air as altitude increases.
Less air means less oxygen available for
combustion.
Your snowmobile can be adjusted to over-
come most of the problems found in high-alti-
tude riding. Carburetor adjustments are the
most important. Less air at high altitude
makes the air/fuel ratio too rich, which can
cause poor performance. Common problems
are hard starting, bogging, and plug fouling.
Proper carburetion adjustments will correct
the air/fuel ratio. Be sure to have a Yamaha
dealer make these adjustments.
Remember:
Less air at higher altitude means there is less
horsepower available, even with proper car-
buretion. Expect acceleration and top speed
to be reduced at higher altitudes.
To overcome operating with less power at
high altitudes, your snowmobile may also re-
quire different settings for the drive chain
gears and V-belt clutch to avoid poor perfor-
mance and rapid wear. If you plan to operate
your snowmobile at an altitude different from
the area where you bought it, be sure to con-
sult a Yamaha dealer. The dealer can tell you
if there are any changes necessary for the al-
titude where you plan to ride.
CAUTION:
ECS00430
The drive chain gears and V-belt clutch
should be adjusted when operating above
a high altitude of 900 m (3000 ft). Consult a
Yamaha dealer.
ESU11950
Valve clearance
The valve clearance changes with use, result-
ing in improper air-fuel mixture and/or engine
noise. To prevent this from occurring, the
valve clearance must be adjusted by a
Yamaha dealer at the intervals specified in
the periodic maintenance chart.
Headlight unit bolt tightening torque:
3 Nm (0.3 m·kgf, 2.2 ft·lb)
U8GM10E0.book Page 46 Friday, April 27, 2007 6:43 PM