Husqvarna 455 Rancher - Manual (Page 32)

32 – English
MAINTENANCE
High speed jet H
At the factory the engine is adjusted at sea level. When
working at a high altitude or in different weather
conditions, temperatures and atmospheric humidity, it
may be necessary to make minor adjustments to the high
speed jet.
CAUTION! If the high speed jet is screwed in too far, it
may damage the piston/cylinder.
When test run at the factory, the high speed jet is set so that
the engine satisfies the applicable legal requirements at the
same time as achieving maximum performance. The
carburettor’s high speed jet is then locked using a limiter cap
in the fully screwed out position. The limiter cap limits the
potential to adjust the high speed jet to at most half a turn.
To adjust the carburettor correctly you should contact a
mechanic with access to a rev counter.
CAUTION! As the spark is cut off, the rev counter does not
show speeds higher than 13600 rpm.
Correctly adjusted carburettor
When the carburettor is correctly adjusted the machine
accelerates without hesitation and 4-cycles a little at full
throttle. It is also important that the chain does not rotate at
idle. If the L-jet is set too lean it may cause starting difficulties
and poor acceleration. If the H-jet is set too lean the machine
will have less power, poor acceleration and could suffer
damage to the engine.
Checking, maintaining and servicing
chain saw safety equipment
Chain brake and front hand guard
Checking brake band wear
Brush off any wood dust, resin and dirt from the chain brake
and clutch drum. Dirt and wear can impair operation of the
brake.
Regularly check that the brake band is at least 0.6 mm thick
at its thinnest point.
Checking the front hand guard
Make sure the front hand guard is not damaged and that there
are no visible defects such as cracks.
Move the front hand guard forwards and back to make sure it
moves freely and that it is securely anchored to the clutch
cover.
Checking the inertia brake release
Place the chain saw, with the engine switched off, on a stump
or other stable surface. Release the front handle and let the
saw fall by its own weight, rotating around the rear handle
towards the stump.
When the bar hits the stump the brake should be applied.
Note! All service and repair work on the machine demands
special training. This is especially true of the machine’s
safety equipment. If your machine fails any of the checks
described below we recommend that you take it to your
service workshop.