Maintenance; Carburetor Adjustment - Dolmar MS-4520 U Instruction Manual

6. MAINTENANCE

The direction of the felling of the trunk depends on
the sector of use of the disk saw, a determined incli-
nation of the blade, and the diameter of the trunk in
question.
- For trunks of up to 3 cm in diameter, the disk saw can
be used with "hatchet strokes", in other words, cutting
from the opposite side foreseen for the falling of the
trunk.
- For trunks of from 3 to 7 cm in diameter, the disk saw
must never be held horizontally, but always at a slight
angle from upwards downwards to prevent the blade
from jamming.
The thicker the diameter of the trunk, the greater this
inclination must be (Fig. 29).
- Trunks of more than 7 cm in diameter can be also felled
with high-power brushcutter, but this operation should
be performed only occasionally because a power saw
is more appropriate in cases such as these.
Try to avoid even the smallest stones, piles of earth,
small pieces of wood, and any other hidden objects in
the grass.
If you happen to strike some large object, if the cutting
tool suddenly jams due to overloading, if too much grass,
stringy vegetal matter or bark gets wound up inside the
machine, reduce the speed to the minimum and then
disengage the clutch.
Make sure that the blade (which turns through in-
ertia) has come to a halt, otherwise stop it against
the ground in a safe place and then switch off the
engine.
Unhook the brushcutter from the safety belt and position
it on the ground in order to make sure that the cutting tool
has not undergone any damage, such as the cracking/
breakage of teeth, etc., and replace if required. If the
tool has got tangled up in stringy vegetal matter, put on
a pair of gloves and use the correct utensil to completely
remove all the tangled material.
ALLTHE MACHINE'S SAFETY SYSTEMS AND
EQUIPMENT MUST BE MAINTAINED IN OP-
ERATION ALL THROUGHOUT USE.
The brushcutter transmits vibrations produced by the
operation of the single-cylinder explosion engine to the
operator that can be rather exhausting after prolonged
use. For this reason, we recommend making regular
pauses during work.
In order to minimise this effect, the machine is provided
with a number of expressly studied rubber vibration-
dampers. Check to make sure that these vibration damp-
ers are always in place and in good condition, or else
have them replaced by a specialised service centre.
PERFORM ALL REPAIR AND ASSEMBLY
OPERATIONS ONLY WITH THE ENGINE
SWITCHED OFF (EXCEPT THOSE RE-
GARDING THE CARBURETOR).
After a few hours of forceful working, we recommend
letting the engine turn for a few minutes at minimum
level in order to permit it to cool down thanks to the air
currents created by the flywheel.
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6. MAINTENANCE

6.1 Carburetor adjustment

The carburetor must be adjusted by a qualified techni-
cian or our own Assistance Center.
During normal operation, the carburetor level may
change slightly, especially when changes occur in work-
ing altitude or after many hours of use, due to variations
in the surrounding temperature or pressure.
Proceed as follows to re-adjust the carburetor level:
Adjustment of MINIMUM level:
- Screw down the minimum screw marked by the letter
"L" clockwise (Part. 1, Fig. 30) gently until it comes to
rest on the base without applying excessive force.
- From this position, unscrew it by 1 turn for WT-series
carburetors and by 4 turns for WYK-series carbure-
tors.
- Start the engine, and without accelerating, find the
point where the engine is running at its maximum level
by screwing or unscrewing the screw marked "L" by
approximately 1/8 of a turn at a time.
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- After the maximum level has been found, unscrew the
screw marked "L" by 1/8
- Use the butterfly valve (Part. 3, Fig. 29) adjustment
screw to bring the engine to a speed of around 2800
rpm. This adjustment permits rotation at the minimum
level just beneath the clutch coupling in the clutch
case.
Make sure that the cutting organ does not
rotate when the engine is running at min-
imum.
Adjustment of MAXIMUM level
- With the engine on and completely accelerated, rotate
the maximum level screw marked with the letter "H"
(part. 2, Fig. 30) by approximately 1 opening turn
and then either screwing it down or unscrewing it
until the maximum level is reached. Bear in mind
that screwing this screw down makes the carburetion
more lean, and that unscrewing the screw enriches
the mixture.
In order to obtain the correct level, the operation must
be performed with the engine warmed up.
The adjustment varies depending on whether it is per-
formed exclusively on the engine, on the engine with the
disk saw mounted, or on the machine with nylon head
with 2 or more wires attached.
We therefore advise you to assign the ad-
justment of the carburetor level to a quali-
fied technician or one of our own service
centers.
of a turn (grease).
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