User Manual

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Now let's check out the "float needle & seat" setting.
This is the single most critical setting on a Walbro carb! Walbro offers a "setting gauge" to properly set the
height of the lever for your particular carb. If you don't have one, the setting will be a trial & error adjustment
and a real pain in the butt since you have to open up the carb to make the adjustment. For general purposes, the
lever will be almost perfectly parallel to the carb base. This will get you close. If the lever is too high, your
engine will tend to run a little erratic at idle. If the lever is too low, your idle will be OK but it will tend to run
lean on midrange and highend. It may also run the float cavity "dry" at full throttle and die, regardless of your
highspeed /lowspeed needle settings.
The needle valve seat is pressed into the carb base, and you should not remove this without having the correct
tools and setting gauges. Do not remove it!
Typical PROBLEMS POSSIBLE solutions
The engine stalls when accelerated
Highend needle way too lean, or lowend needle slightly lean
Four strokes as fast idle, mid RPM
Lowend needle too rich, float diaphragm needle lever slightly too high
Engine goes lean in flight
Highend needle slightly lean AND lowend needle is rich, float needle
lever may be set too low
Engine goes rich in flight
this is a special problem with cowled in engines. the float diaphragm
cover vent will need work (SEE NOTE 1)
Engine runs good, but no idle at all
There's crap in the idle jets, the carb will have to be removed and
cleaned. You may also have an air leak at the base of the carb. The
throttle butterfly could be damaged or worn out.