Air Filter; Spark Plug; Muffler; Needle Bearing Maintenance - Husqvarna 51 Operator's Manual

Air filter

The air filter must be regularly cleaned from dust and dirt in
order to avoid:
• Carburetor malfunctions
• Starting problems
• Engine power reduction
• Unnecessary wear on
the engine parts
• Abnormal fuel consumption
Clean the air filter daily or
more often if the air is
exceptionally dusty in the
working area.
• Disassemble the air filter by
removing the cylinder cover
and unscrew the filter.
When reassembling, make
sure that the filter is tight
against the filter holder.
Clean the filter by brushing
or shaking it.
• A more thorough cleaning of
the filter is obtained by
washing it in water and
soap.
An air filter, which is used for
some time, cannot be cleaned
completely. Therefore it must
be replaced by a new one,
with regular intervals.
IMPORTANT! A damaged air
filter must always be
replaced.

Spark plug

The spark plug condition is influenced by:
• An incorrect carburetor setting.
• Wrong fuel mixture (too much oil in the gasoline).
• A dirty air filter.
These factors cause deposits on the spark plug electrodes,
which may result in malfunction and starting difficulties.
If the engine is low on
power, difficult to start or
runs poorly at idling speed,
always check the spark plug
first. If the spark plug is dirty,
clean it and check the
electrode gap. Readjust if
necessary. The correct gap is
0,5 mm (0,020"). The spark
plug should be replaced after
about a month in operation or
earlier if the electrodes are
badly eroded.
IMPORTANT! Always use the
recommended spark plug
type. An incorrect spark plug
can severely damage the
piston/cylinder.
MAINTENANCE

Muffler

The muffler is designed in
order to reduce the noise level
and to direct the exhaust
gases away from the operator.
The exhaust gases are hot
and can contain sparks, which
may cause fire if directed
against dry and combustible
material. Some mufflers are
equipped with a special
screen. If your saw has this
type of muffler, you should
clean the screen at least once
a week. This is done with a
wire brush.
CAUTION! The screen must
be replaced, if damaged. The
saw will be overheated, if the
screen is clogged. This results
in damage on the cylinder and
the piston. Never use a saw
with a clogged or defective
muffler.

Needle bearing maintenance

The clutch drum is equipped
with one of the following chain
sprockets:
• Spur sprocket (A) (the chain
• Rim sprocket (B)
Both versions have built-in
needle bearing at the drive
shaft, whitch has to be
0,5 mm
greased regularly (once a
week).
NOTE! Use only high quality
bearing grease.
sprocket is welded on the
drum)
(exchangeable)
A
B
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