1
TUNING
Rich and Lean: An internal combustion
engine needs a specific ratio or mixture
of air and fuel for best performance. This
mixture is delivered by the carburetor.
In the following discussion numerous
references will be made to the air and
fuel mixture (air/fuel ratio) being rich
or lean. Rich refers to a mixture with an
excess of fuel. Lean refers to a mixture
with an excess of air.
Float height
Parts involved:
• Float
• Inlet Needle
The float height controls the fuel level
in the float bowl. This adjustment
determines the point at which the inlet
needle opens as the fuel level drops
in the bowl. Float height is usually
measured with the float bowl removed
and is specified from the carburetor
body to an edge or surface on the
float. The float should be resting on
the inlet needle but not depressing the
spring under the needle stem when
this measurement is taken. To adjust,
carefully bend the tab where it makes
contact with the inlet needle.
The float height should be adjusted
before any other adjustments are
made. A higher fuel level will cause
a richer mixture and possibly excess
overflow from the vents. A lower fuel
level will a cause a leaner mixture and
could lead to an engine miss or cut-out
while cornering. Start at the specified
height and change as needed for best
performance on different type of tracks.
The float drop should also be checked.
The proper adjustment will prevent the
needle from pulling too far out of the
inlet seat and becoming stuck in the
open position.
Animal, 206, and M-series
