Adjusting The Carburetor - Stihl BR 800 Service Manual

9.4.6 Installing the Pump Diaphragm and Strainer
Push the strainer (7), convex side facing inwards, into
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its seat in the carburetor (10).
Fit the spring (3) in the end cover (2).
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Fit washer (4) on the spring.
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Place the gasket (5) on the end cover (2) so that the
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holes engage the pegs (arrows).
Place the pump diaphragm (6) on the gasket (5) so
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that the holes engage the pegs (arrows).
Place the carburetor (10) on the end cover (2) with
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gasket (5) and pump diaphragm (6) so that the pegs
(arrows) on the end cover engage the holes in the
carburetor (9).
Insert and tighten down the screws (1) firmly.
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Install the carburetor, @ 8.3.
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Adjust the carburetor, @ 9.5.
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9.5

Adjusting the Carburetor

If the air filter is dirty or damaged: Replace air filter.
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Install the air filter.
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If a spark arrestor is fitted: Clean the spark arrestor.
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If the spark arrestor is damaged: Install a new spark
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arrestor.
Check throttle cable.
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If throttle cable adjustment is not correct. Adjust the
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throttle cable.
Standard setting
Turn the high speed screw (H) clockwise as far as
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stop.
Turn the low speed screw (L) clockwise as far as stop.
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H 2,5
Open the high speed screw (H) 2.5 turns
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counterclockwise.
Open the low speed screw (H) 2 turns
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counterclockwise.
Adjust engine speeds with the aid of the EDT 8
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tachometer 5910 850 1009 or MDG 1 analyzer
5910 840 0210 (tolerance ± 200 rpm).
BR 800
Start the engine and warm it up for about 1 minute at var-
ying speeds.
If necessary: Turn the idle speed screw (LA) clockwise
until the engine runs smoothly.
↑
Use the idle speed screw (LA) to set
the engine speed to 3,300 rpm.
↑
← no
Turn the low speed screw (L) counterclockwise and set
the engine speed to 2,500 rpm.
Set the engine speed to 7,500 rpm with the high speed
screw (H) (starting with H = 2.5 turns open).
Engine stops while idling
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Erratic idling behavior, engine stops even though setting
of LA screw has been corrected, poor acceleration, idle
speed too high
Idle setting is too lean
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Erratic idling behavior
Idle setting is too rich.
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L 2
Adjusting carburetor for operation at high altitude
If you use the machine at high altitude, the engine will not
deliver optimum power. The carburetor setting can be
adjusted to obtain optimum engine power.
LA
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If the machine is later used at a low altitude, the engine
may overheat.
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Adjusting carburetor for operation at temperatures below
–10°C
The engine will not accelerate properly if the blower is
used at temperatures below –10°C. The carburetor can be
adjusted to obtain normal engine acceleration in such
conditions.
Adjusting Idle Speed
Turn the low speed screw (L) clockwise or
counterclockwise to obtain the maximum
engine speed.
Is the engine speed between 3,100 and
3,500 rpm?
Turn the idle speed screw (LA) clockwise until the
engine runs smoothly.
Turn the low speed screw (L) counterclockwise until
the engine runs and accelerates smoothly.
Turn the low speed screw (L) clockwise until the
engine runs and accelerates smoothly.
Start the engine and warm it up for about 1 minute at
varying speeds.
Turn high speed screw (H) clockwise (no further than
stop) until optimum engine power is reached.
Carry out the standard setting.
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↓ yes
↓ yes
↓
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