2007 Yamaha Motorsports Apex Owners Manual - Page 66
2007 Yamaha Motorsports Apex Manual
Page 66 highlights
E_8fp.book Page 11 Tuesday, March 28, 2006 4:35 PM ESU04540 Adjusting the high-altitude settings Operating at high altitude reduces the performance of a gasoline engine about 3% for every 305 m (1,000 ft) of elevation. This is because there is less air as altitude increases. Less air means less oxygen available for combustion. Your snowmobile utilizes an electronic fuel injection system that delivers the optimal air/fuel ratio required by the engine. Therefore, the fuel injection system does not need to be adjusted, even for operation at high altitude. Remember: Less air at higher altitude means there is less horsepower available, even with the optimal air/fuel ratio. 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. CAUTION: @ The drive chain gears and V-belt clutch should be adjusted when operating above a high altitude of 900 m (3,000 ft). Consult a Yamaha dealer. @ ESU00348 Adjusting the 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. 8-11