2003 Polaris Deep Snow Snowmobiles Service Manual, Page 54Get this manual
MAINTENANCE At idle and low speeds, the exhaust valve is held in the "low port" position by the return springWhen throttle is applied (and RPM begins to increase) rising cylinder pressure is applied to the under side of the bellows via the actuation portThis forces the exhaust valve upward against spring pressureThe valve continues to move upward toward the "High Port" position as cylinder pressure, horsepower, and RPM increase
V.E.SMaintenance
Due to the simplicity of V.E.Sdesign, maintenance is limited to periodic inspection and cleaning of system componentsThe V.E.Sshould be disassembled, inspected, and cleaned (remove carbon deposits) every 1000 to 2000 miles, depending on operating conditionsTo ensure maximum performance and minimize required maintenance, Polaris recommends the use of VES Synthetic Cycle lubricantThe use of other lubricants may cause improper function of the valve mechanism, and increase the frequency of required cleaning due to excessive buildup of carbon depositsValve cover Spring Valve cap Bellows Washer Bolt