Stihl BT 45 - Maintenance and Repairs

30 BT 45
The limiter cap has to be removed
from the high speed screw (H) only
if it is necessary to replace the high
speed screw (H), clean the
carburetor or adjust it from scratch.
After removing the limiter cap it is
necessary to carry out the basic
setting.
: Push the puller (2)
5910 890 4501, with thr groove
facing you, between the limiter
cap (1) and carburetor body and
pry the cap off. If the limiter cap is
stuck on the screw, turn the puller
over so that its groove faces the
carburetor body. Pry off the
VA
932RA316
12
limiter cap.
Limiter caps that have been
removed once may be damaged
and must not be re-used. Always
install a new limiter cap.
– Screw down both adjusting screw
(H and L) clockwise until their are
against their seats.
Now make the following
adjustments:
– Open the high speed screw(H)
1 1/2 turns counterclockwise.
– Open the low speed screw (L) on
full turn counterclockwise.
VA
932RA331
L
H
: Line up the new cap for the high
speed screw (H) against the rich
stop and press it on only as far as
the second noticeable detent
position.
The stop limits the adjustment
range of the high speed screw (H) to
VA
249RA129
270°
a 3/4 turn.
Do not press the cap against the
carburetor body as it will otherwise
be damage.
– Carry out standard setting
- b 8.4.6
Correct operation of the carburetor
is only possible if atmospheric
pressure and internal fuel tank
pressure are equal at all times. This
is ensured by the tank vent.
In the event of trouble with the
carburetor or the fuel supply
system, always check the tank vent
and replace it if necessary.
Testing the tank vent
– Open the tank cap slowly and
drain the tank. Refit the tank cap,
making sure it is tight.
– Disconnect the two fuel hoses
from the carburetor - b 8.6.2
– Seal one of the fuel hoses with a
suitable plug.
– Connect vacuum pump
0000 850 3501 to the other fuel
hose and produce a vacuum in
the fuel tank by operating the
pump quickly.
– If the vacuum remains
unchanged, install a new tank
vent.
If the vacuum slowly dissipates, the
tank vent is in order.
8.4.7 Basic Setting 8.5 Tank Vent
8.5.1 General