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Stihl MS251 User Manual

Stihl MS251
132 pages
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STIHL MS 251
WARNING To reduce the risk of
kickback injury use STIHL reduced kickback bar
and STIHL low kickback chain as specified in
this manual or other available low kickback
components.
ADVERTENCIA Para reducir el
riesgo de lesionarse como resultado de un
culatazo, utilice la barra y la cadena de
contragolpe reducido de la forma especificada
en este manual o de otros componentes
reductores de contragolpe.
Read Instruction Manual thoroughly before
use and follow all safety precautions –
improper use can cause serious or fatal injury.
Antes de usar la máquina lea y siga todas las precauciones
de seguridad dadas en el manual de instrucciones – el uso
incorrecto puede causar lesiones graves o mortales.
Instruction Manual
Manual de instrucciones
Question and Answer IconNeed help?

Do you have a question about the Stihl MS251 and is the answer not in the manual?

Stihl MS251 Specifications

General IconGeneral
Weight4.9 kg (10.8 lbs)
Chain OilomaticYes
Displacement45.6 cc (2.8 cu. in.)
Fuel Capacity13.2 oz
Guide Bar Length16 in
Chain Gauge0.050"

Summary

Guide to Using this Manual

Pictograms

Explanation of symbols and icons used on the machine and in the manual.

Symbols in Text

Explanation of how text and illustrations are used to convey instructions.

Safety Precautions and Working Techniques

The Operator and Physical Condition

Operator requirements regarding physical and mental health for safe chain saw use.

Proper Clothing

Guidance on appropriate protective apparel for chain saw users.

Vibrations and Health Risks

Information on vibration-related health issues like whitefinger disease and carpal tunnel syndrome.

Eye, Head, and Hearing Protection

Recommendations for wearing safety glasses, face shields, hard hats, and hearing protection.

Safe Operation and Transport

Warnings against modifying the saw, operating damaged units, and safe transport procedures.

Fuel and Fueling Procedures

Fuel Specifications and Warnings

Fuel requirements, quality, ethanol content, and handling safety precautions.

Filler Cap Operation

Instructions for opening, closing, and troubleshooting the fuel filler cap.

Before Operation Checks

Chain Tension Check

Importance and procedure for checking saw chain tension before operation.

Starting the Chain Saw Safely

Recommended methods for safely starting the chain saw, including kickback warnings.

Holding and Controlling the Saw

Proper grip, body positioning, and footing for controlling the chain saw.

Working Conditions and Hazards

Ladder and Overreach Precautions

Warning against working on ladders or overreaching to avoid loss of control.

Exhaust Fumes and Dust Hazards

Health risks from fumes, dust, and chemicals, with ventilation and control measures.

Operating Instructions Overview

Key operating procedures, including throttle lock, bumper spike use, and chain brake.

Reactive Forces and Kickback Management

Kickback Explained and Prevention

Detailed explanation of kickback, its causes, and key steps to prevent it.

Chain Saw Kickback Standard

Details of the ANSI/OPEI B175.1-2012 standard for chain saw kickback performance.

Kickback Injury Reduction Devices

STIHL Quickstop Chain Brake

Explanation of the Quickstop chain brake system and its activation mechanisms.

Front Hand Guard Importance

The role of the front hand guard in kickback situations and chain brake activation.

Low Kickback Chains and Reduced Kickback Bars

STIHL Recommendations for Kickback Reduction

STIHL's advice on using green-labeled reduced kickback bars and low kickback chains.

Low Kickback Saw Chain Definition

Definition and performance requirements of low kickback saw chains per ANSI/OPEI B175.1-2012.

Avoiding Kickback and Reactive Forces

To Avoid Kickback

Twelve key steps to prevent kickback situations.

Avoiding Pull-in

Steps to prevent pull-in, a type of reactive force.

Limbing, Bucking, and Felling Safety

Limbing and Bucking Safety Precautions

Safety advice for limbing, bucking, cutting small logs, and logs under tension.

Felling Preparation and Tree Condition

Considerations before felling, including tree condition and environmental factors.

Felling Techniques and Safety

Felling Instructions and Escape Paths

General instructions for felling, including distance from people and escape paths.

Conventional and Open-face Cutting

Steps for making conventional and open-face felling notches.

Large Tree Felling Methods

Sectioning or plunge-cut methods for felling large diameter trees, highlighting dangers.

Maintenance, Repair, and Storage

Genuine STIHL Parts and Repair Guidelines

Importance of using genuine STIHL parts and following repair instructions.

Spark Plug and Ignition System Care

Maintenance and warnings related to the spark plug and ignition system.

Muffler and Chain Brake Maintenance

Care for the muffler, spark arresting screen, and chain brake system.

Cutting Attachment Assembly

Chain, Bar, and Sprocket Matching

Ensuring correct matching of chain, bar, and sprocket for performance and safety.

Chain Scabbard Usage

Proper use and selection of chain scabbards for safety.

Mounting the Bar and Chain

Side Chain Tensioner Procedures

Steps for mounting the bar and chain with a side chain tensioner.

Quick Chain Tensioner Procedures

Steps for mounting the bar and chain with a quick chain tensioner.

Chain Brake Release and Fitting

Procedures for releasing the chain brake and fitting the saw chain.

Tensioning the Saw Chain

Tensioning During Cutting

Procedure for retensioning the saw chain while cutting, for both tensioner types.

Checking Chain Tension

Chain Fit Check and Retensioning

How to check chain fit and retension if necessary.

Frequent Tension Checks

Importance of frequent checks, especially for new chains.

Fuel System and Fueling

Fuel Specifications and Handling

Fuel requirements, quality, ethanol content, and safety precautions for handling.

Filler Cap Operation and Refueling

Instructions for opening, closing, and troubleshooting the fuel filler cap during refueling.

Chain Lubrication System

Lubricant Types and Warnings

Recommended lubricants and warnings against using waste oil.

Filling Chain Oil Tank

Procedure for filling the chain oil tank.

Chain Brake System Operation

Chain Brake Engagement and Disengagement

When to engage and release the chain brake for safety during operation.

Chain Brake Maintenance and Warnings

Maintenance schedule and warnings for chain brake functionality.

Winter Operation Adjustments

Carburetor Shutter Adjustment

Instructions for adjusting the carburetor shutter for winter and summer operation.

Starting and Stopping the Engine

Master Control Lever Positions

Explanation of the Master Control Lever positions for engine control.

Engine Starting Procedures

Starting steps for standard and Easy2Start models, including safety.

Troubleshooting Engine Start Issues

Steps to take if the engine does not start, including flooded carburetor.

General Operating Instructions

Break-in Period Guidelines

Guidelines for operating a new machine during its break-in period.

Work Precautions and Chain Tension

Important notices for safe operation during work, including chain tension checks.

Checking Chain Tension During Use

Importance of checking and maintaining chain tension during operation.

Guide Bar Maintenance

Guide Bar Turning and Cleaning

Tips for turning, cleaning, and measuring the guide bar for longevity.

Groove Depth Specification

Minimum groove depth requirements for guide bars.

Shroud and Air Filter System

Shroud Removal and Refitting

Steps for removing and reinstalling the shroud.

Air Filter Types and Selection

Description of fleece and HD2 filters for different operating conditions.

Air Filter Cleaning Procedures

Filter Removal and Cleaning

Procedure for removing, cleaning, and reinstalling the air filter.

Thorough Filter Cleaning Methods

Methods for deep cleaning the air filter when basic cleaning is insufficient.

Engine Management and Carburetor

Carburetor Adjustment Overview

Basic information and standard settings for the carburetor.

Idle Speed Adjustment Procedures

Procedures for setting idle speed and troubleshooting issues.

Spark Plug and Screen Maintenance

Spark Arresting Screen Maintenance

Checking and cleaning the spark arresting screen in the muffler.

Spark Plug Inspection and Installation

Inspecting, cleaning, and installing the spark plug for engine performance.

Rewind Starter Maintenance

Prolonging Starter Rope Life

Tips for maintaining the starter rope and grip.

Machine Storage Procedures

Short-term and Long-term Storage

Instructions for storing the machine for short and long periods.

Chain Sprocket Inspection and Replacement

Chain Sprocket Wear Check

How to check chain sprocket wear and when to replace it.

Replacing the Chain Sprocket

Steps for replacing the chain sprocket, including related components.

Saw Chain Maintenance and Sharpening

Sharp Chain Cutting Benefits

Benefits of using a properly sharpened saw chain for cutting performance.

Saw Chain Condition Checks

Checking the saw chain for cracks, damage, and wear.

Sharpening Angles and Procedures

Correct angles for sharpening saw chain cutters and side plates.

Depth Gauge Setting and Sharpening Tools

Depth Gauge Setting Guide

How to set the depth gauge to control chip thickness.

Sharpening Tools and Table

Table of sharpening tools and guidelines for proper sharpening.

Maintenance and Care Schedule

Machine and Controls Checks

Routine inspection and functional tests for the machine and its controls.

Brake, Fuel, and Lubrication System Care

Maintenance for the chain brake, fuel, and oil systems.

Chain, Guide Bar, and Air Filter Care

Maintenance for the saw chain, guide bar, and air filter.

Carburetor and Spark Plug Maintenance

Anti-Vibration Elements and Screws

Checking anti-vibration elements and tightening accessible screws, nuts, and bolts.

Carburetor and Spark Plug Service

Carburetor adjustment, spark plug inspection, and muffler checks.

Definitions of Components

Component Definitions List

Detailed explanations of various chain saw components and their functions.

Main Parts Identification

Diagram of Main Parts

Illustrated breakdown of the chain saw's main components.

List of Main Parts

Numbered identification of each component shown in the main parts diagram.

Technical Specifications

Engine and Fuel System Specs

Technical data for engine displacement, power, fuel system, and capacity.

Weight and Cutting Attachments

Specifications for machine weight and recommended cutting attachments.

Guide Bar and Saw Chain Specs

Details on Rollomatic E guide bars and low kickback saw chains.

Accessories and Spare Parts Ordering

Special Accessories Information

How to obtain information on special accessories available for the product.

Ordering Spare Parts Information

Information required for ordering spare parts, including model and part numbers.

Maintenance and Repair Responsibilities

User Maintenance and Warranty Terms

User's role in performing maintenance and warranty considerations.

STIHL Part Identification

How to identify genuine STIHL parts.

Disposal of Used Equipment

Environmental Disposal Guidelines

Instructions for environmentally friendly disposal of the product.

STIHL Emission Control Warranty

Warranty Coverage Details

Details of the warranty period and coverage for emission-related parts.

Owner's Warranty Responsibilities

User's responsibilities for maintenance and warranty claims.

STIHL Warranty Commitment

STIHL's warranty commitment regarding design and materials of the engine.

Warranty Period and Diagnosis Process

Warranty period start, diagnosis procedures, and cost of non-defective component testing.

Warranty Work and Parts Policy

Emission-Related Parts Covered

List of specific parts covered by the emission control system warranty.

Trademarks and Brand Names

STIHL Registered Trademarks

List of registered trademarks associated with STIHL.

STIHL Common Law Trademarks

List of STIHL's common law trademarks.

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