12.4.1 Standard Setting - Stihl MS 270 User Manual

12.4.1 Standard Setting

The limiter caps need be removed
from the adjusting screws only if it is
necessary to replace the high speed
screw (H) or low speed screw (L),
clean the carburetor or carry out the
standard setting.
Perform the two following
operations:
After removing the limiter cap it is
necessary to carry out the standard
setting.
1
Turn the left-hand limiter cap (1)
of high speed screw (H) counter-
clockwise as far as stop until the
limiter cap lugs are in line with the
carburetor openings.
Turn the right-hand limiter cap (2)
of low speed screw (L) clockwise
as far as stop. Turn the limiter cap
back one quarter turn until its lugs
are in line with the carburetor
openings.
80
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.
1
2
– Screw down both adjusting
screws until they are against their
seats.
On MS 270, make the following
adjustment:
– Open the high speed screw (H)
(1) 1 1/8 turns.
– Open the low speed screw (L) (2)
1 1/4 turns.
On MS 280, make the following
adjustment:
– Open the high speed screw (H)
(1) 1 1/4 turns.
– Open the low speed screw (L)
(2) 1 1/4 turns.
Adjusting engine idle speed
– Check the air filter and clean or
replace as necessary.
– Check chain tension.
– Warm up the engine.
Adjust idle speed with a tachometer.
Adjust specified engine speeds
within tolerance of +/- 200 rpm.
2
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. Set engine's maximum speed
to 13,500 rpm with the high
speed screw (H).
MS 270, MS 280