Basic Setting (Carburetor With Limiter Caps) - Stihl MS 290 Manual

11.4.3 Basic Setting (Carburetor
with Limiter Caps)
The limiter caps need to be
removed from the adjusting screws
only if it is necessary to replace the
high speed screw (H) or low speed
screw (L) or clean the carburetor.
Carry out the two following steps:
After removing the limiter cap it is
necessary to carry out the basic
setting.
: Turn the limiter caps (arrows) of
the H and L screws counter-
clockwise as far as stop so that
the lugs of the limiter caps line up
with the carburetor openings.
MS 290, MS 310, MS 390
: Insert puller 5910 890 4500 in
center of limiter caps, apply slight
pressure and screw home
counterclockwise until the limiter
caps come out of the carburetor
body.
After removing the limiter caps, first
carry out the basic setting.
– Screw both adjusting screws
down onto their seats.
Make the following adjustments:
–
Open the high speed screw (H) one
full turn clockwise.
– Open the low speed screw (L)
one full turn clockwise.
– Set the engine speed to
2,800 rpm with the low speed
screw (L).
– If no tachometer is available,
mount the limiter caps, see step 6
Fine tuning (with tachometer)
– Check the air filter and clean or
replace as necessary.
– Check and clean or replace spark
arresting screen (if fitted).
– Check chain tension.
– Warm up the engine.
Adjust engine idle speed with a
tachometer. Adjust specified engine
speeds to within a tolerance of +/-
200 rpm.
1. Adjust engine speed with idle
speed screw (LA) to 3,300 rpm.
2. Turn low speed screw (L)
clockwise or counterclockwise
to obtain maximum engine
speed.
If this speed is higher than
3,700 rpm, abort the procedure and
start again with step 1.
3. Use the idle speed screw (LA)
to set engine speed again to
3,300 rpm.
4. Set the engine speed to
2,800 rpm with the low speed
screw (L).
5. Use the high speed screw (H) to
adjust the maximum engine
speed to:
12,500 rpm (MS 290)
13,000 rpm (MS 310 and MS390)
6. Install new limiter caps, noting
that the stop lugs on the limiter
caps must line up with the
openings in the carburetor.
Always install new limiter caps.
Limiter caps that have been
removed once may be damaged
and must not be re-used.
73