Briggs & Stratton 555700 Guide page 12

WALBRO PZ CARBURETOR
The Walbro PZ 26 has been specifically
calibrated for this application. The following
guide should help you with set-up and
maintenance. Replacement components are
available through your authorized source of
supply. An additional jet kit is also available
at 557012 – This kit was specifically
designed to cover the majority of your
gasoline jetting requirements.
CAUTION: After connecting the throttle
cable to the throttle slide valve or after
EVERY TIME the throttle slide is removed,
always remove air filter and visually
check that the throttle slide closes fully
and moves freely in the bore.
STARTING
This carburetor is equipped with a choke
valve for starting. When the engine is cold,
lift choke lever to start engine. As engine
warms push choke lever down to open
choke for normal operation.
FLOAT HEIGHT
The float height controls the fuel level in the
float bowl, which can also affect carburetor
performance. Set float height according to
specification before any other tuning.
IDLE / LOW SPEED
Tuning of the engine at idle and low
speeds is accomplished by adjusting the
Idle Mixture Screw or changing the size of
the Pilot Jet (also called Slow Jet). The jet
size or diameter in millimeters is stamped
on the jet (38 = .38mm orifice). The Idle
Mixture Screw is a fuel adjustment, so
closing the screw or turning it clockwise
will lean the fuel mixture, and opening the
screw or turning it counterclockwise will
richen the fuel mixture.
To adjust the Idle Mixture Screw proceed
as follows. Turn the Idle Mixture Screw in
until it lightly seats or stops. Back the Screw
out the specified number of turns. Warm
the engine and set the Idle Speed Screw
slightly higher than the desired idle rpm.
Turn the Idle Mixture Screw in or out to
obtain the highest rpm. Turn the Idle Speed
Screw to the desired idle rpm. A slightly
rich idle mixture is usually better for
acceleration.
If a smooth idle cannot be obtained with
the Idle Mixture screw between 1/4 – 2
turns out from closed, a different size Pilot
Jet may be needed. The proper size Pilot
Jet will allow for smooth acceleration from
an idle and steady engine speed up to 1/4
throttle opening.
MIDRANGE / PART THROTTLE
The Jet Needle primarily controls fuel flow
between 1/4 and 3/4 throttle opening.
The Jet Needle has five notches and a C-
clip on the top of it. To richen the part
throttle operation, move the clip to the next
lower notch. This will hold the needle
farther out of the nozzle. To lean the part
throttle operation, move the clip to the next