Husqvarna 340, 345, 346XP,350, 351, 353 manual Basic adjustment for EPA II carburetors, Check that

Repair instructions

Appendix A

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/35116”

•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).

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	C = 13 700
346XP	C = 14 300

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	D = 1 1/2
346XP/351	D = 1 1/2

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	E = 12 000
346XP	E = 13 000

6. Adjust the idle speed to ”F” rpm.

Model
340/345/350	F = 2 700
346XP/351	F = 2 700

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.

50 – English