Yamaha 2003 yz85, Owner'S Service Manual

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T U N
* marked: In case of hard breathing, check the carburetor breather hoses for clogging.
Closed to 1/4 throttle
Poor acceleration
White smoke
Use jet needle with a larger diam-
eter.
Turn in pilot air screw.
Unstable at low speeds
Pinking noise
Lower jet needle clip position.
(1 groove down)
Turn in pilot air screw.
Poor response at
extremely low speed Reduce pilot jet calibration No.
Turn out pilot air screw.
If not effect, reverse the above
procedures. Dragging brake
Overflow from carburetor
Poor response in the low
to intermediate speeds Raise jet needle clip position.
If this has no effect, lower the jet
needle clip position.
Poor response when
throttle is opened quickly Check overall settings.
Use main jet with a lower calibra-
tion no.
Raise jet needle clip position.
Use jet needle with a larger diam-
eter.
If these have no effect, use a main
jet with a higher calibration no.
and lower the jet needle clip posi-
tion. Check air filter for fouling.
Poor engine operation Turn in pilot air screw.
Adjust the throttle stop screw. Check throttle valve operation.
Symptom Setting Checking
This should be taken simply for an example. It
is necessary to set the carburetor while check-
ing the operating conditions of the engine and
discoloration of spark plugs.
Normally, carburetor setting is made by means
of the main jet, jet needle clip position, pilot jet
and pilot air screw.
SETTING