TM 2008 4 Stroke User Manual Download

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ENGLISH

CARBURETOR -

CARBURETOR - IDLE SPEED ADJUSTMENT

IDLE SPEED ADJUSTMENT

IDLE SPEED ADJUSTMENT (A)

(A)

The adjustment of the idle speed greatly influences the engine start,
this means that an engine with the idle speed correctly adjusted will be
easier to start than an engine with an incorrect idle speed.
The idle speed is adjusted using the adjustment knob (1) and the
mixture adjustment screw (2). The adjustment knob is used to adjust
the basic position of the throttle valve. The mixture adjustment screw is
used to adjust the mixture for the idle speed, which flows through the
idle speed system up to the engine. By turning in a clockwise direction,
the quantity of fuel decreases (lean mixture), by turning in an
anticlockwise direction, the quantity of fuel increases (rich mixture).

TO SET IDLE SPEED FUNCTIONING CORRECTLY, PROCEED AS
FOLLOWS:

1 Screw the mixture adjustment screw (2) until it stops, without force,

then unscrew it untill you obtain the basic adjustment envisioned by
TM (see Engine Technical Data).

2 Warm-up the engine
3 Use the adjustment knob (1) to adjust the number of revs. of the

normal idle speed (1600 - 1800/min).

4 Slowly turn the mixture adjustment screw (2) in a clockwise direction

until the number of revs of the idle speed begins to decrease. Keep
this position in mind and now turn the mixture adjustment screw
slowly in an anticlockwise direction until the number of revs of the
idle speed begins to decrease again. Set the point between these
two positions in which the number of idle speed revs is highest. If
there is a notable increase in the number of revs., reduce the number
of revs to the normal level using the adjustment knob (1) and repeat
the procedure from point 4. Anyone using the motorcycle for pure racing
will set a leaner mixture of about 1/4 of a turn (in a clockwise direction) with
respect to the ideal value, because the engine will become hotter than
normal.
NOTE: If the described methods are followed and satisfying results
are not obtained, the cause could be a Pilot jet with unsuitable
dimensions.
a) If the mix adjustment screw is screwed right down without variation
of the number of revs of the idle speed, a smaller Pilot jet must be
installed.
b) If the engine switches off with the mix adjustment screw still open
by two turns, a larger Pilot jet must be installed. Obviously, after the
jet has been replaced, adjustment must be carried out again from
the beginning.

5 Now, adjust the number of revs. of the idle speed desired using the

adjustment knob.

6 In presence of large variations of external temperature and altitude,

the idle speed must be set again.

To adjust the idle speed mixture screw, a very short screwdriver
may be required. Notches may be useful on the handgrip.

BASIC INDICA

ASIC INDICA

ASIC INDICATIONS REGARDING CARB

TIONS REGARDING CARB

TIONS REGARDING CARBURET

URET

URETOR

WEAR

The throttle valve, jet needle, needle jet (when present) and the float
needle valve are subject to great wear caused by engine vibration. As a
consequence the carburetor may malfunction (e.g. enrichening of the
mixture). These parts must therefore be controlled after 200 hours.

FRAME AND ENGINE MAINTENANCE