Husqvarna SB - User Manual

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B0400066

SERVICE

English 1 (4)

SB, 136, 141, 55, 340, 345, 350, 346 XP, 353, 357 XP, 359,

395 XP, 3120 XP, 336, 339 XP, 334 T, 338 XPT,

Basic adjustment for EU 1, 2004-12

Basic adjustment for EU 1 models with carburettors equipped with caps to meet the EU (European

Union) emission regulations.

Carburettor with caps

This means that the chain saw is equipped with adjustment limiters (= caps) on the carburettors’

high speed (H) and low speed (L) adjusting needles. The purpose is to prevent the chain saw

operator from changing the setting to above EU allowed emission levels.

The caps limit the adjustment range to a maximum of 1/2 turn on both H- and L-needles.

Replacement of L- and/or H-speed needles or complete carburettor (1 and 2)

After replacing the carburettor or high speed and/or low speed needle on EU certified products, a

basic adjustment must be carried out as described below in order to meet the EU requirements.

This is to keep exhaust emissions within the requirements specified by EU.

This instruction is made for EU certified products only.

1. Replacement of L speed or/and H speed needles

The caps can be removed to achieve richer or leaner adjustments. This can be done with a pair of

cutting pliers pulling the caps from the needles or by using a caps removal tool (part no 531 03 05-

01 for Walbro two-stage limiter cap) or part no 531 03 03-98 for Zama caps.

2. Replacement of carburettor

To set the needles correctly an adjustment sleeve is fitted over the caps from the factory on spare

part carburettors to lock them in maximum allowed settings. On all carburettors be sure that both

caps are set to the rich side before fixing them to the needles.

NOTE 1: After April 2003 there is a different system for setting the speed on models 136/141. See SB B0400020.

NOTE 2: On the complete spare part carburettor, the L-needle is adjusted from the factory.

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Overview

Function Description
Important Technical Specifications
H-Needle Adjustment (Initial Turns from Closed Position - "A" turns)
H-Needle Adjustment (Top Speed - "B" rpm - initial setting)
H-Needle Adjustment (Top Speed - "C" rpm - final setting)
L-Needle Adjustment (Initial Turns from Closed Position - "D" turns)
L-Needle Adjustment (Engine Warm-up RPM - "E" rpm)
L-Needle Adjustment (Idle Speed - "F" rpm)
Bar Length Specifications (for adjustment conditions)
Usage Features
Maintenance Features

This document provides a service bulletin for basic carburettor adjustment on various Husqvarna chainsaw models, specifically for EU 1 models manufactured in 2004-12. The primary function of this adjustment is to ensure that the chainsaws comply with EU emission regulations. This is achieved by limiting the adjustment range of the carburettor's high-speed (H) and low-speed (L) adjusting needles using "caps." These caps restrict the adjustment range to a maximum of 1/2 turn on both H- and L-needles, preventing operators from setting the saw to exceed allowed emission levels.

Function Description:

The core function of this service bulletin is to guide technicians through the process of correctly adjusting the carburettor after replacing either the H-speed and/or L-speed needles or the complete carburettor assembly on EU-certified products. This ensures that the exhaust emissions remain within the EU-specified requirements. The adjustment process involves a series of steps for both H-needle and L-needle replacement, including initial settings, engine warm-up, and fine-tuning using a tachometer to achieve specific RPM values. The caps, which are adjustment limiters, are crucial for maintaining compliance with emission standards.

Important Technical Specifications:

The document lists numerous Husqvarna chainsaw models covered by this bulletin, including:

SB, 136, 141, 55, 340, 345, 350, 346 XP, 353, 357 XP, 359, 395 XP, 3120 XP, 336, 339 XP, 334 T, 338 XPT.

For each model, specific technical specifications are provided for carburettor adjustment:

H-Needle Adjustment (Initial Turns from Closed Position - "A" turns):

136/141: A = 2
55: A = 1 1/4
340/345/350/353: A = 3/4
346 XP: A = 3/4
357 XP: A = 3/4
359: A = 3/4
395 XP: A = 3/4
3120 XP: A = (non adjustable fixed jet)
336/339 XP: A = 1 1/2
334 T/338 XPT: A = 1 1/2

H-Needle Adjustment (Top Speed - "B" rpm - initial setting):

136/141: B = 12 000
55: B = 12 000
340/345/350/353: B = 12 000
346 XP: B = 13 000
357 XP: B = 13 500
359: B = 12 500
395 XP: B = 13 000
3120 XP: B = (non adjustable fixed jet)
336/339 XP: B = 12 500
334 T/338 XPT: B = 12 500

H-Needle Adjustment (Top Speed - "C" rpm - final setting):

136/141: C = 13 500
55: C = 12 500
340/345/350/353: C = 12 700
346 XP: C = 14 300
357 XP: C = 14 000
359: C = 13 100
395 XP: C = 12 500
3120 XP: C = (non adjustable fixed jet)
336/339 XP: C = 13 100
334 T/338 XPT: C = 12 900

L-Needle Adjustment (Initial Turns from Closed Position - "D" turns):

136/141: D = 1 1/2
55: D = 1 1/4
340/345/350/353: D = 1 1/2
346 XP: D = 1 1/2
357 XP: D = 1 1/2
359: D = 1 1/2
395 XP: D = 1 1/2
3120 XP: D = 1 (non adjustable fixed jet)
336/339 XP: D = 1 1/4
334 T/338 XPT: D = 1 1/4

L-Needle Adjustment (Engine Warm-up RPM - "E" rpm):

136/141: E = 13 200
55: E = 12 000
340/345/350/353: E = 12 700
346 XP: E = 13 000
357 XP: E = 13 500
359: E = 12 500
395 XP: E = 12 000
3120 XP: E = (non adjustable fixed jet)
336/339 XP: E = 12 500
334 T/338 XPT: E = 12 500

L-Needle Adjustment (Idle Speed - "F" rpm):

136/141: F = 3 000
55: F = 2 600
340/345/350/353: F = 2 700
346 XP: F = 2 700
357 XP: F = 2 700
359: F = 2 700
395 XP: F = 2 500
3120 XP: F = (non adjustable fixed jet)
336/339 XP: F = 2 800
334 T/338 XPT: F = 2 800

Bar Length Specifications (for adjustment conditions):

136/141: 14"
55: 18"
340/345/350/353: 16"
346 XP: 16"
357 XP: 16"
359: 16"
395 XP: 24"
3120 XP: 28" (non adjustable fixed jet)
336/339 XP: 15"
334 T/338 XPT: 14"

Usage Features:

The document outlines a detailed procedure for carburettor adjustment, emphasizing the importance of specific conditions and tools:

Initial Setup: Before any adjustments, the air filter must be clean, and the cylinder cover fitted. Adjusting with a dirty air filter can lead to a lean fuel mixture and potential engine damage. An approved bar and chain combination, as specified in the Operator's manual, must be mounted. The chain should be tensioned to allow approximately 5 mm (0.2 inch) of lift from the bar.
Cap Removal and Installation: Caps can be removed using cutting pliers or specialized tools (part no 531 03 05-01 for Walbro two-stage limiter cap, or 531 03 03-98 for Zama caps). When installing new carburettors, an adjustment sleeve ensures the needles are locked in maximum allowed settings, and both caps should be set to the rich side before fixing them to the needles.
Adjustment Tools: A narrow blade screwdriver (Ref.no. 531 00 48-63) with a max blade width of 2 mm (0.08 inch) is used for adjusting the needles through the cap hole. A tachometer is required to accurately set the engine's top speed and idle speed. A 5 mm (0.2 inch) mandrel (e.g., locking pin ref.no. 502 02 61-03) is used to gently knock the caps into position after adjustment.
Engine Operation: The engine must be started and allowed to run for approximately 1 minute until warm before final adjustments are made. The idling speed is adjusted using the T-screw.
Safety: The document implicitly emphasizes safety by ensuring correct chain tension and proper carburettor settings to prevent chain rotation at idle.

Maintenance Features:

This service bulletin itself is a critical maintenance feature, providing a standardized procedure for carburettor adjustment to ensure optimal performance and compliance. Key maintenance-related aspects include:

Regular Checks: The document highlights the need to check that the H-cap remains adjusted to its richest setting (turned counterclockwise to stop) and that the H-needle does not rotate during this check. Similarly, the L-cap must be checked to ensure it is at its richest position and that the L-needle does not rotate.
Post-Adjustment Fine-Tuning: While the outlined procedure provides a basic carburettor adjustment, the document notes that further fine adjustments, within the limits allowed by the caps, may be necessary to achieve optimum performance. Operators are advised to consult the Operator's manual for these additional adjustments.
Specific Model Notes: For models 136/141 after April 2003, a different speed setting system applies (refer to SB B0400020). For complete spare part carburettors, the L-needle is factory-adjusted. The 3120XP model has a non-adjustable fixed jet for both H and L needles, meaning certain adjustment steps are not applicable.
Air Filter Importance: The repeated emphasis on a clean air filter underscores its role in proper carburettor function and engine health. Replacing the air filter is also mentioned as a condition during adjustments.

In summary, this service bulletin is an essential guide for technicians to perform precise carburettor adjustments on specific Husqvarna chainsaw models, ensuring compliance with EU emission regulations while maintaining optimal engine performance and longevity. It details the steps, required tools, and technical specifications for both H- and L-needle adjustments, along with important pre-adjustment conditions and post-adjustment checks.