2004 Yamaha Motorsports Big Bear 400 Owners Manual - Page 125
2004 Yamaha Motorsports Big Bear 400 Manual
Page 125 highlights
10. Install the air filter element. 11. Install the air filter case cover by fastening the holders. 12. Install the seat. NOTE: The air filter element should be cleaned every 20-40 hours. It should be cleaned more often if the ATV is operated in extremely dusty areas. Each time air filter element maintenance is performed, check the air inlet to the air filter case for obstructions. Check the air filter element rubber joint to the carburetor and manifold fittings for an airtight seal. Tighten all fittings securely to avoid the possibility of unfiltered air entering the engine. _ _ CAUTION: _ Never operate the engine with the air filter element removed. This will allow unfiltered air to enter, causing rapid engine wear and possible engine damage. Additionally, operation without the air filter element will affect carburetor jetting with subsequent poor performance and possible engine overheating. _ 8-16