Husqvarna 225B - Manual (Page 20)

20
– English
MAINTENANCE
The fuel quantity required in relation to the air flow,
provided by the opening in the throttle, is adjusted
by the L and H jets. If they are screwed clockwise,
the air/fuel mixture becomes leaner (less fuel) and if
they are screwed counterclockwise, the mixture
becomes richer (more fuel). A leaner mixture gives
rise to a higher engine speed and a richer mixture
gives rise to a lower engine speed.
The T screw regulates the idling speed. Turning the
T screw clockwise will increase the idling speed;
turning it counterclockwise will lower the idling
speed.
The carburetor has been carefully preset at the fac-
tory. However, additional adjustment may be required
due to climate, altitude, gasoline and type of two-
stroke engine oil used. The instructions below
describe how carburetor adjustment should be
carried out.
Function
The carburetor governs the engine speed via the
throttle. Air and fuel are mixed in the carburetor. The
air/fuel mixture is adjustable. To utilize the blower’s
maximum output, the settings must be correct.
The carburetor has three means of adjustment:
H = High speed jet
L = Low speed jet
T = Adjustment screw for idling
Carburetor
H L T
Basic (factory) settings
The carburettor is preset to the basic settings when
the blower is tested at the factory. These basic
settings are the following:
Turn the H jet screw CCW against its stop.
Turn the L jet screw CCW against its stop.
The recommended idling speed is 3,000 rpm.
Adjustment
To adjust the low speed jet (L)
1. Check that tube (15) and nozzle (14) are
mounted on the blower.
2. Turn the H and L jet screws all the way CCW
against the stop.
3. Start the blower as described on page 13 and
alternate letting it run at idling speed and at half
throttle for 1 – 2 minutes to warm up. If the
engine will not run at idling speed, turn the T
screw CW until it does.
4. Turn the T jet screw until the engine runs
precisely at idling speed without dying.
5. Make a fine adjustment, turning the L screw to
let the engine run at max. idling speed. Then
turn the L screw max. 1/4 of a turn CCW.
6. Turn the T screw to increase the engine speed,
if necessary.
To adjust the high speed jet, H
NOTE !
When setting the H jet, do not let the
engine run at full throttle for more than 10
seconds at a time. Alternate by letting the
engine run at idling speed for at least 10
seconds before giving it full throttle again.
1. Start the blower as described on page 13 and
alternate letting it run at idling speed and at half
throttle for 1 – 2 minutes to warm up.
2. Give the engine full throttle and adjust the H jet
screw until the engine runs at max. speed.
3. Turn the H jet screw 1/8 of a turn counter-
clockwise (less than 1/8 of a turn if a stop
restricts this adjustment).