Appendix A, Carburettor - Epa Models - Husqvarna 340 Workshop Manual
Husqvarna gas chain saw workshop manual
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Also See for 340:
- Operator's manual (69 pages) ,
- Workshop manual (52 pages) ,
- Basic adjustment (4 pages)
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Repair instructions
Basic adjustment for EPA II carburetors
After replacing the carburetor or high speed and/or low
speed needle on an EPA (The US Environmental
Protection Agency) certified product a basic adjustment
must be carried out as described below in order to meet
the EPA-requirements. This to achieve as low emissions
as possible. This instruction is made for USA & Canada
only. On EPA carburetors both the H- and L-needles are
fitted with caps to prevent the chain saw operator from
changing the adjustment above EPA standard. The caps
can be removed to achieve richer or leaner adjustments.
To set the needles correctly an adjustment sleeve is fitted
from the factory over the caps to lock them in maximum
allowed settings.
When correctly set the caps must be fixed on the nee-
dles. The adjustment sleeve then can be removed. Over
the caps on complete sparepart carburetor, there is a
plastic sleeve which is intended to lock the caps at the
richest position (anticlockwise towards stop) during the
time that the needles are adjusted. When the adjustment
is complete and the caps have been fixed on the nee-
dles, the sleeve is no longer of any function and can be
removed.
NOTE! On the complete spare part carburetor, the L-
needle is adjusted from the factory.
NOTE! Before making any adjustments the following
must be done!
• Mount, for this model, approved bar & chain combina-
tion (See Technical data in the Operator's manual).
Model
340/345/350
16"
346XP/351
16"
• The chain should not be tensioned more than that it
remains ~0,2 inches to the bar.
• Mount a new air filter.
Replacement of the H-needle or complete carburetor
1. Screw the new H-needle to the bottom and turn it
counterclockwise "A" turns.
Model
340/345/350
A = 3/4
346XP/351
A = 3/4
2. Check that:
The H-cap is adjusted to its richest setting. (Turned
counterclockwise to stop). The cap is not fixed to the
needle, it should rotate independently. Adjust the L-cap
to a center position (1/4 turn counterclockwise =
minimum, 1/4 turn clockwise = maximum).
3. Start the engine. If necessary, adjust the idling speed
with the T-screw until the chain stops.
4. Adjust the H-needle to give a top speed of "B" rpm.
Model
340/345/350/351
B = 12 000
346XP
B = 13 000
Use a narrow blade screwdriver (Ref.no. 531 00 48-63)
and insert it through the hole in the cap (max. blade width
2 mm/0.08 inch).
50
– English
Appendix A
5. Let the engine run at "B" rpm ~ 1 minute, until warm.
6. Adjust the H-needle to a top speed of "C" rpm.
Model
340/345/350/351
346XP
7. Check that the H-cap is still adjusted to its richest
setting. (Turned counterclockwise to stop). NOTE!
The H-needle must not rotate!
8. Gently knock the H-cap into position. Use a 5 mm/0.2
inch mandrel (for ex. the locking pin for the bevel gear
ref.no. 502 02 61-03). This is a basic carburetor
adjustment. Further fine adjustments, within the limits
the caps allow, may be necessary to achieve optimum
performance. See the Operator's manual.
Replacement of the L-needle
1. Take off the cap from the L-needle using e.g. a pair of
cutting pliers and unscrew the needle.
2. Screw the new L-needle to the bottom and then turn it
counterclockwise "D" turns.
Model
340/345/350
346XP/351
3. Press a new L-cap on the L-needle to the first stop,
which means that the cap is not fixed to the needle, it
should rotate independently.
4. Adjust the L-cap to the richest position (turned
counterclockwise to stop) without turning the needle.
5. Let the engine run at ~ "E" app.1 minute until warm
and then let it run on idle.
Model
340/345/350/351
346XP
6. Adjust the idle speed to "F" rpm.
Model
340/345/350
346XP/351
7. Adjust the L- needle until the highest possible idling
speed is achieved and then turn the
L-needle 1/2 turn counterclockwise. Use a narrow
blade screwdriver w. ref.no. 531 00 48-63 and insert
through the hole in the cap (max. blade width 2 mm/
0.08 inch) .
NOTE! If the chain rotates, turn the idling speed
screw (T) counterclockwise until the chain stops.
8. Check that the L-cap is still adjusted to its richest
position. (Turned counterclockwise to stop).
NOTE! The L-needle must not rotate!
9. Gently knock the L-cap into position. Use a 5 mm/0.2
inch mandrel (for ex. the locking pin for the bevel gear
ref.no. 502 02 61-03).
This is a basic carburetor adjustment. Further fine
adjustments, within the limits the caps allow, may be
necessary to achieve optimum performance. See the
Operator's manual.
C = 13 700
C = 14 300
D = 1 1/2
D = 1 1/2
E = 12 000
E = 13 000
F = 2 700
F = 2 700
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Troubleshooting
