Appendix A, Carburettor - Epa Models - Husqvarna 340 Workshop Manual

Carburettor – EPA models
Basic adjustment for EPA carburettors
After replacing the carburettor or high speed and/or
low speed needle on an EPA (The US Environmen-
tal 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 instruc-
tion is made for USA only.
On EPA carburettors 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 over the caps to lock
them in maximum allowed setting. When correctly
set the caps must be fixed on the needles. The
adjustment sleeve then can be removed.
NOTE! Before making any adjustments the
following must be done.
• Mount, for this model, approved bar & chain
combination for a 16" bar (see Technical data in
the Operator's manual).
• 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 carbu-
rettor
1. Screw the new H-needle to the bottom and turn
it counterclockwise "3/4" turns.
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 "A"
rpm.
Model 340/345/350/351
Model 346XP
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).
5. Let the engine run at 13 000 rpm ~1 minute,
until warm.
Appendix A
6. Adjust the H-needle to a top speed of "B" rpm.
7. Check that the H-cap is still adjusted to its
8. Gently knock the H-cap into position. Use a 5
This is a basic carburettor 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 e.g. a pair of
2. Screw the new L-needle to the bottom and then
3. Press a new L-cap on the L-needle to the first
4. Adjust the L-cap to the richest position (turned
5. Let the engine run at ~"C" rpm app. 1 minute
6. Adjust the idle speed to 2 700 rpm.
7. Adjust the L-needle until the highest possible
8. Check that the L-cap is still adjusted to its
A= 12 000
9. Gently knock the L-cap into position. Use a 5
A= 13 000
This is a basic carburettor adjustment. Further fine
adjustments, within the limits the caps allow, may
be necessary to achieve optimum performance.
See the Operator´s manual.
Model 340
Model 345
Model 350/351/346XP
richest setting. (Turned counterclockwise to
stop). NOTE! The H-needle must not rotate!
mm/0.2 inch mandrel (for ex. the locking pin for
the bevel gear ref.no. 502 02 61-03).
cutting pliers and unscrew the needle.
turn it counterclockwise 1 1/2 turns.
stop, which means that the cap is not fixed to
the needle, it should rotate independently.
counterclockwise to stop) without turning the
needle.
until warm and then let it run on idle.
Model 340/345/350/351
Model 346XP
idling speed is achieved and then run the L-
needle 1/2 turn counterclockwise. Use a narrow
blade screw-driver 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.
richest position. (Turned counterclockwise to
stop). NOTE! The L-needle must not rotate!
mm/0.2 inch mandrel (for ex. the locking pin for
the bevel gear ref.no. 502 02 61-03).
B= 12 300
B= 12 700
B= 13 000
C= 12 000
C= 13 000
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English –