ENGLISH
29
CARBURETOR – Adjust idling (DellOrto)*
Idling adjustment of the carburetor strongly affects the engine’s starting behavior.
That is, an engine whose idling speed is adjusted correctly will be easier to start
than one whose idling speed has not been adjusted correctly.
Idling is controlled by the throttle stop screw
1 and the mixture control screw
2. The throttle stop screw is used to adjust the basic position of the throttle. The
mixture control screw is used to control the idle mixture which arrives at the
engine via the idle system. Turning it clockwise will reduce the amount of gaso-
line (lean mixture), turning it counterclockwise will increase the amount of gaso-
line (rich mixture).
TO ADJUST IDLING CORRECTLY, PROCEED AS FOLLOWS:
1 Turn in mixture control screw
2 up to the stop, and turn it back out by 1.5
turns
2 Warm up the engine
3 Use throttle stop screw
1 to adjust normal idling speed (1400-1500 r.p.m.)
4 Turn mixture control screw
2 slowly clockwise until idling speed starts to
decrease. Memorize this position, and turn mixture control screw slowly coun-
terclockwise until the idling speed will decrease again. Adjust the point of the
highest idling speed between these two positions. (The highly competitive user
will make his adjustment 1/4 turn leaner because his engine will heat up more
in competitive use).
NOTE: If you fail to obtain a satisfying result by following the procedure descri-
bed above, an incorrectly dimensioned idling nozzle may be the cause. In case:
a) the mixture control screw has been screwed in up to the stop without cau-
sing any change in rotational speed, a smaller idling jet has to be installed;
b) the engine dies when the mixture control screw is still open by 2 turns, a
larger idling jet needs to be selected;
Naturally, in cases of jet changes, you have to start your adjusting work from
the beginning.
5 Now, use the slide stop screw to adjust the desired idling speed
6 In cases of greater changes in outside temperature and extremely different alti-
tudes, the idling speed should be readjusted.
Basic information on carburetor wear
As a result of engine vibrations, throttle valve, jet needle, and needle jet are sub-
jected to increased wear. This wear may cause carburetor malfunction (e.g.,
overly rich mixture). Therefore, these parts should be replaced after 10000 kilo-
meters (6000 miles).
Adjust hot start device (DellOrto)*
If the hot start button was removed when cleaning the carburetor, re-adjust the
hot start device.
Install carburetor and adjust idling as discribed above. Then unlock nut
3, press
in hot start device
4 and adjust engine rev with adjusting screw 5 to 2000-2500
rpm. Tighten locking nut.
Check float level (DellOrto)*
Stand the carburettor diagonally at about 60° so that the spring in the float needle
valve is not pressed together. In this position, the edge of the float should be paral-
lel with the float bowl sealing surface (see illustration).
Checking axial play of float (DellOrto)*
For proper functioning of the float, there must be an axial play of 0.8 mm (0,03
in). If necessary, slightly abrade and deburr lateral float guide.
1
2
60°
0,8 mm
3
4
5
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