Introduction; Identification; Operation - Toro V Service Manual

INTRODUCTION
Identification
The primer start carburetor is easily identified by
the primer bulb mounted to the aluminum heat
shield/ primer bracket and the black Minion
carburetor body.
This is a single circuit, fixed jet, non-adjustable
carburetor manufactured by The Toro Company.
5
Operation-
As the crankshaft rotates, the piston moves up
and down in the cylinder. alternately creating
pressure or a partial vacuum in the crankcase.
When a vacuum is created by upward pressure
movement, the reed valve opens and air rushes
through the carburetor throat.
The carburetor is a venturi tube ( large at each
end, with a smaller center passage). When air
rushes through this tube air pressure at the
center of the passage is lowered. By inserting a
tube from the carburetor float bowl into the
venturi, lower air pressure at the venturi draws
fuel up through the tube. The fuel/oil mix is then
picked up by, and mixed with, the incoming air.
The fuel/oil/air mixture enters the crankcase
through the reed valves, thereby sustaining
operation of the engine as long as fuel is
supplied to
it.
REED
VALVE
FIRST STROKE
751.2.5130.85
VENTURI, CENTER
I I
Venturi Effect
751.2.5130.8O6
5-4
Service Section