VESPA GT 200, Workshop Manual

Page: 79 / 287

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8.1.4 Weak Mixture
Symptom Possible Cause Operation
Carburetor jets clogged Remove, wash in solvent and dry
with compressed air.
Float valve faulty Check the proper sliding of the float
and the operation of the valve.
Level in float bowl too low Restore the level in the float bowl
bending the fuel inlet needle thrust
blade on the float so that the float is
parallel to the chamber surface when
the carburetor is in an up-side down
position.
Tank breather clogged Restore proper tank aeration.
Feed pipes choked or throttle Restore proper fuel flow.
Weak mixture
Intake manifold cracked or
clamps poorly tightened Replace the intake connection and
check for any abnormal air leakage.
8.1.5 Low Compression
Symptom Possible Cause Operation
Incorrect valve adjustment Adjust valve clearance
Valves overheated Remove the cylinder head and the
valves, then grind or replace the
valves
Valve seat deformed/worn Replace the head assembly
Low
compression
Cylinder worn; piston rings
worn or broken Replace cylinder-piston assembly or
piston rings