2003 Polaris ATV Trail Boss 330 Factory Service Manual, Page 32Get this manual
MAINTENANCE
ENGINE-TO-FRAME GROUND
Inspect engine-to-frame ground cable connectionBe sure it is clean and tightEngine Ground Strap
AIR FILTERPRE-FILTER SERVICE
It is recommended that the air filter and pre filter be replaced annuallyWhen riding in extremely dusty conditions, replacement is required more oftenThe pre filter should be cleaned before each ride using the following procedure: 1Lift up on the rear of the seat2Pull the seat back and free of the tabsNOTE: When reinstalling seat, make sure the slots in the seat engage the tabs in the fuel tank3Remove clips from air box cover (A) and remove coverInspect the gasket (E)It should adhere tightly to the cover and seal all the way around4Loosen clamp and remove air filter assembly (BC)C