2008 Yamaha Motorsports RS Vector Owners Manual - Page 52

Periodic maintenance Your snowmobile can be adjusted to overcome most of the problems found in high-altitude 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 carburetion. Expect 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 settings for the drive chain gears and V-belt clutch to avoid poor performance and rapid wear. If you plan to operate your snowmobile at an altitude different from the area where you bought it, be sure to consult a Yamaha dealer. The dealer can tell you if there are any changes necessary for the altitude where you plan to ride. ECS00430 12. Install the headlight unit bolts, and then tighten them to the specified torque. Headlight unit bolt tightening torque: 3 Nm (0.3 m·kgf, 2.2 ft·lb) 13. Place the wire harness in the original position, 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. Therefore, carburetor adjustments should be left to a Yamaha dealer, who has the necessary professional knowledge and experience. ESU11940 CAUTION: 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, resulting 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. High-altitude settings 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 combustion. 46