Kawasaki KX65 - Owner's Manual - Tuning
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TUNING
Carburetor Tuning
Tuning a carburetor is not the mysterious science
many racers believe it to be. One only needs to
establish a basic knowledge of the identification and
function of carburetor components as well as how
they work together to do the job well.
Temperature-and
altitude-related
mixture
adjustment
Condition*
Mixture will be Adjustment
Cold air
Leaner
Richer
Warm air
Richer
Leaner
Dry air
Leaner
Richer
Low altitude
Standard
None
High altitude
(above 1 500 m
or 4 900 ft)
Richer
Leaner
*at constant atmospheric pressure and humidity
The main jet size should be increased or de-
creased by one to five sizes and the engine tested
until its power is maximum.
Symptoms of Improper Mixture
If your machine exhibits one or several of the
symptoms listed below, it may need carburetor
tuning. Before attempting any changes, however,
make sure that everything else is in good shape
and properly tuned.
Check the condition of the
spark plug, make sure the ignition timing is correct,
service the air cleaner element and decarbonize the
muffler.
If your machine has run properly on a certain track
in the past and then starts running poorly with the
same carburetor settings, the problem is almost cer-
tain to be elsewhere; changing the carburetor set-
tings in such a case would probably be a waste of
time.
Symptoms when the mixture is too rich
•
Poor acceleration
•
Misfire at low engine speeds
•
Excessive smoke
•
Spark plug fouling
•
A “deep” exhaust noise
Symptoms when the mixture is too lean
•
Pinging or rattling
•
Erratic acceleration
•
Same as when running out of fuel
•
High engine temperature