Walbro Corporation

Donald C Ross

George M Pattullo

David L Speirs

Mark S Swanson

Matthew A Braun

James E Van Allen

Steven L Hammett

David L Berg

A carburetor fuel mixture adjustment assembly including a threaded cylindrical needle valve receptacle formed in a carburetor main body and intersecting a fuel passage. A needle valve body is threaded into the needle valve receptacle and includes a needle that extends into an axially-aligned needle seat orifice portion of the fuel passage. The needle is axially movable within the needle seat orifice by rotation of the needle valve body to control how much of the orifice is open to fuel flow. A valve spring disposed between a head of the needle valve body and the carburetor main body biases the head away from the carburetor main body. A needle stabilizer engages and cooperates with the valve spring in laterally biasing the needle into one position relative to the needle seat orifice. The lateral bias assures constant fuel flow through the orifice by resisting needle movement.

Carburetor fuel mixture adjustment assembly

A carburetor for a two or four stroke engine having a diaphragm chamber for supplying fuel to the air intake passage of the engine, and a reservoir for primer fuel. A manually operable pump or bulb draws fuel from the diaphragm chamber into the reservoir. An outlet passage leads from the reservoir to deliver primer fuel to the engine. A normally closed manually operable valve or button is provided for opening the outlet passage. The capacity or the reservoir is varied as a function of ambient temperature by a temperature compensator.

Carburetor having temperature-compensated purge/primer

A cap and method for limiting the range of adjustment of a fuel flow metering valve in a carburetor. The cap has a body with an arm projecting generally radially outwardly therefrom to abut against a stop carried by the carburetor to limit valve rotation and a passage therein for telescopically axially receiving the head end of a shank of the valve. Portions within the passage enable the cap to be retained in the shank of the valve in a freely rotating first position during assembly and arm orientation, and in a second position securing the cap to the valve to limit adjustment and maintain emissions calibration. Preferably, the cap may also be moved to a third position to releasably drivingly engage the valve to perform fuel flow adjustment before securing the cap to the valve. The cap can also be prepositioned angularly relative to an adjusted position of the valve before it is moved to its second position on the valve to limit the extent of subsequent adjustment of the valve.

Carburetor needle valve adjustment limiter cap and method of use

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Cass City, MI, United States of America

Donald C Ross