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Stihl MS 240

Stihl MS 240
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STIH)
STIHL MS 240, 260
2013-09

Table of Contents

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Stihl MS 240 Specifications

General IconGeneral
Chain pitch3/8"
Oil Capacity0.2 L
Guide bar length (recommended)40 cm
Engine Power2.0 kW (2.7 bhp)
Displacement41.6 cm³

Summary

Introduction to the STIHL MS 240, 260 Service Manual

Symbols and Meanings in the Manual

Explains symbols used in the manual for clarity and correct interpretation of instructions.

Safety Precautions for STIHL MS 240, 260

Specifications for STIHL MS 240, 260 Models

Engine Specifications

Details engine displacement, bore, stroke, power, speed, and clutch engagement.

Fuel System Specifications

Lists leakage test values for carburetor and tank vent, and fuel type.

Ignition System Specifications

Specifies air gap, spark plug type, and electrode gap for the ignition system.

Chain Lubrication Specifications

Details oil pump type, delivery rate, and control method for chain lubrication.

Tightening Torque Specifications for STIHL MS 240, 260

Troubleshooting Common STIHL MS 240, 260 Issues

Troubleshooting Clutch Issues

Lists common clutch problems, their causes, and recommended remedies for proper function.

Troubleshooting Chain Drive, Brake, and Tensioner

Addresses issues with chain wear, brake function, and chain tensioner operation.

Troubleshooting Chain Lubrication

Identifies causes for no oil, oil loss, or insufficient oil delivery in the chain lubrication system.

Troubleshooting Rewind Starter

Lists causes and remedies for common rewind starter problems like rope issues or slow rewinding.

Troubleshooting Ignition System

Covers engine running issues, misfires, and irregular sparks, linking to causes and remedies.

Troubleshooting Ignition System (No Spark)

Addresses the condition of 'no spark' and lists potential causes and their solutions.

Troubleshooting Carburetor Issues

Details common carburetor problems like flooding, poor acceleration, and stalling, with causes and remedies.

Troubleshooting Carburetor Idle and Power

Covers engine not idling, idle speed too high, stalling at idle, and power loss.

Troubleshooting Engine Performance

Addresses engine not starting, low power, erratic running, and overheating with their respective causes and solutions.

Cutting Attachment Service for STIHL MS 240, 260

Cutting Attachment: Chain Catcher

Instructions for removing and installing the chain catcher, including torque specifications.

Clutch Service for STIHL MS 240, 260

Clutch Drum Removal and Installation

Details the process for removing, inspecting, and installing the clutch drum, including wear checks.

Chain Brake System Service for STIHL MS 240, 260

Chain Brake Operation Check

Explains how to check the efficiency and proper functioning of the chain brake mechanism.

Chain Brake Band Removal and Installation

Provides step-by-step instructions for removing and installing the chain brake band.

Chain Brake Band Removal and Installation (Continued)

Continues instructions for removing and installing the brake band, including specifics for different versions.

Chain Brake Lever Service

Details the process for removing, inspecting, and installing the brake lever and associated components.

Chain Brake Lever Service (Continued)

Continues instructions for servicing the brake lever, including spring and pivot pin checks.

Chain Brake Cam Lever Service

Explains how to remove, check, and install the cam lever that locks the hand guard.

Chain Brake Anchor Pins Service

Covers removal and installation of anchor pins, emphasizing proper seating and threadlocking.

Side Chain Tensioner Removal

Details steps for removing the side chain tensioner assembly, including spur gear and tensioner slide.

Side Chain Tensioner Removal (Continued)

Continues the removal process for the side chain tensioner, focusing on the adjusting screw and thrust pad.

Front Chain Tensioner Service

Provides instructions for servicing the front chain tensioner, including part inspection and lubrication.

Quick Chain Tensioner Service

Mentions that the quick chain tensioner is in the chain sprocket cover, referring to another section.

Bar Mounting Studs Service for STIHL MS 240, 260

Engine Service for STIHL MS 240, 260

Engine: Muffler and Spark Arresting Screen

Covers removal and installation of the muffler, heat shield, gasket, and spark arresting screen.

Engine: Muffler and Spark Arresting Screen (Continued)

Continues instructions for muffler installation, including heat shields, gaskets, and exhaust casing.

Engine: Leakage Test Procedure

Explains the importance of leakage tests for oil seals, gaskets, and casting cracks affecting the engine.

Engine: Leakage Test Procedure (Continued)

Details the procedure for performing vacuum and pressure tests on the engine crankcase for leaks.

Engine Leakage Test Preparations

Lists steps for preparing the engine for a leakage test, including removing parts and fitting test flanges.

Engine Leakage Test: Vacuum Test

Describes how to perform a vacuum test to check oil seal integrity and interpret results.

Engine Leakage Test: Pressure Test

Details the pressure test procedure to check crankcase airtightness and locate leaks.

Engine: Oil Seal Replacement

Covers removing and installing oil seals on both the ignition and clutch sides of the engine.

Engine: Oil Seal Replacement (Continued)

Continues oil seal replacement, including specific tools and procedures for different sides.

Engine: Shroud Removal and Installation

Explains how to remove and install the engine shroud, including handling slotted nuts and stop buffers.

Engine: Shroud Removal and Installation (Continued)

Continues shroud installation, including reflector foil and specific steps for versions with a decompression valve.

Engine: Cylinder Removal and Installation

Outlines steps for removing the cylinder, including associated parts like the shroud, carburetor, and flywheel.

Engine: Cylinder Removal and Installation (Continued)

Details the cylinder removal process, including detaching hoses and screws, and preparing for reinstallation.

Engine: Cylinder Installation

Covers installing the cylinder, including gasket alignment, piston ring compression, and sealing faces.

Engine: Crankshaft Removal and Installation

Provides detailed procedures for removing and installing the crankshaft, covering both clutch and ignition sides.

Engine: Crankshaft Removal and Installation (Continued)

Details the installation of the crankshaft on the ignition side, including bearing lubrication and heat application.

Engine: Crankshaft Installation (Ignition Side)

Continues ignition side crankshaft installation, focusing on using tools and ensuring proper seating.

Engine: Crankshaft Installation (Clutch Side)

Details the installation of the crankshaft on the clutch side, including gasket placement and screw usage.

Engine: Crankshaft Removal and Installation Steps

Summarizes the steps for removing and installing the crankshaft, covering both sides and tool usage.

Engine: Crankcase and Bearing Service

Covers replacement of crankcase halves, bearings, and seals, and inspection for damage.

Engine: Crankcase and Bearing Service (Continued)

Continues crankcase inspection, cleaning sealing faces, and bearing replacement procedures.

Engine: Crankcase Bearing Replacement

Details oil seal and ball bearing replacement on both ignition and clutch sides of the crankcase.

Engine Piston Removal

Explains how to remove the piston from the connecting rod, including snap ring handling.

Engine Piston Installation

Details the process for installing the piston onto the connecting rod, including needle cage and snap ring procedures.

Engine Piston Ring Service

Covers checking and installing piston rings, including cleaning grooves and correct orientation.

Engine Decompression Valve Service

Explains how to remove, check, and install the decompression valve, including sealing cone inspection.

Ignition System Service for STIHL MS 240, 260

Ignition System: Fixed Timing

States that ignition timing is fixed and not adjustable during repair work.

Ignition System: Ignition Module Description

Describes the ignition module, its components, and electrical connections.

Ignition Module Removal and Installation

Details the steps for removing and installing the ignition module, including shroud and carburetor box cover removal.

Ignition Module Removal and Installation (Continued)

Continues ignition module installation, covering boot, lead, ground wire, and retainer removal/installation.

Ignition Module Installation and Setting

Covers fitting the ignition module, setting the air gap using a gauge, and connecting wires.

Ignition System: Testing the Ignition Module

Explains how to test the ignition module using specialized testers (ZAT 3/4) for spark generation.

Ignition System: Spark Plug Boot and Ignition Lead Service

Details how to remove, install, and prepare new ignition leads and spark plug boots.

Ignition System: Flywheel Service

Covers flywheel removal and installation, including checking for damage, key seating, and air gap setting.

Ignition System: Short Circuit Wire Testing

Explains how to test the short circuit wire for continuity and breaks using an ohmmeter.

Short Circuit Wire Removal and Installation

Details removing and installing the short circuit wire and ground wire, including wiring harness management.

Ignition System: Ground Wire Service

Covers testing the ground wire's contact and continuity, and replacing the wiring harness if damaged.

Ignition System Troubleshooting Flowchart

A flowchart to diagnose engine running problems related to the ignition system, guiding through checks and remedies.

Ignition System Troubleshooting Flowchart (Continued)

Continues the troubleshooting flowchart, guiding checks for spark, air gap, flywheel, short circuit wire, and ignition lead.

Ignition System Troubleshooting Flowchart (Continued)

Continues the flowchart, covering switch shaft operation, spark plug boot, and finally engine running status.

Rewind Starter Service for STIHL MS 240, 260

Rewind Starter: General Information

Discusses common rewind starter issues like stiffness due to dirt or low temperatures, and lubrication.

Rewind Starter Removal and Installation

Details how to remove and install the rewind starter, including fan housing and hand guard.

Rewind Starter: Pawl Service

Covers removing and installing the pawl, including spring clip and lubrication.

Rewind Starter: Rope Rotor Service

Explains how to remove and install the rope rotor, including relieving spring tension and checking for wear.

Rewind Starter: Rope and Grip Replacement

Details replacing the starter rope and grip, including tying knots and fitting caps.

Rewind Starter: Tensioning the Rewind Spring

Describes the procedure for tensioning the rewind spring after installation.

Rewind Starter: Tensioning the Rewind Spring (Continued)

Continues spring tensioning, explaining how to check correct tension and reduce it if necessary.

Rewind Starter: Replacing the Rewind Spring

Covers removing and installing a new rewind spring, including safety precautions and lubrication.

Rewind Starter: Rewind Spring Replacement (Continued)

Continues rewind spring replacement, detailing proper seating, anchor loop positioning, and spring fitting.

AV System Service for STIHL MS 240, 260

AV System: Annular Buffer on Chain Catcher

Details removing and installing the annular buffer on the chain catcher, including lubrication.

AV System: Annular Buffer at Clutch Side

Explains removal and installation of the annular buffer at the clutch side of the engine housing.

AV System: Annular Buffer at Clutch Side (Continued)

Continues annular buffer service at the clutch side, covering plug removal and buffer installation.

AV System: Annular Buffer at Ignition Side

Details removal and installation of the annular buffer on the ignition side of the crankcase.

AV System: Annular Buffer at Ignition Side (Continued)

Continues annular buffer service at the ignition side, including fitting the retaining plate and checking wiring.

AV System: Stop Buffer Service

Covers removing and installing the stop buffer, and checking it for damage.

AV System: Stop Buffer Service (Continued)

Continues stop buffer service, focusing on positioning and ensuring proper seating.

AV System: Handlebar Removal and Installation

Details the process for removing and installing the handlebar, including checking seating and tightening screws.

AV System: Handlebar Removal and Installation (Continued)

Continues handlebar service, covering wire routing and ensuring snug fit.

AV System: Handlebar with Heating Service

Explains procedures for handlebars with heating systems, including disconnecting wires and general compatibility.

AV System: Handlebar with Heating Service (Continued)

Continues service for heated handlebars, detailing wire routing, connector management, and ensuring connections are covered.

Control Levers Service for STIHL MS 240, 260

Control Levers: Switch Shaft Operation

Explains the different positions of the switch shaft (off, run, start) and how to move between them.

Switch Shaft Removal and Installation

Details how to remove and install the switch shaft, including disconnecting the throttle rod and checking the shaft.

Control Levers: Throttle Trigger and Interlock Lever

Covers removal of the air filter, screws, and handle molding, and disconnecting the throttle rod.

Control Levers: Throttle Trigger and Interlock Lever (Continued)

Continues service for throttle trigger and interlock lever, including drift usage, spring attachment, and alignment.

Control Levers: Throttle Trigger and Interlock Lever (Continued)

Continues throttle trigger and interlock lever service, focusing on engagement, spring attachment, and handle molding installation.

Control Levers: Throttle Trigger and Interlock Lever (Continued)

Continues service for throttle trigger and interlock lever, covering handle molding installation and final checks.

Chain Lubrication System for STIHL MS 240, 260

Chain Lubrication: Pickup Body Service

Explains how impurities clog the pickup body filter and how to remove and clean it.

Chain Lubrication: Oil Suction Hose Service

Covers removing and installing the oil suction hose, and checking it for damage or leaks.

Chain Lubrication: Oil Delivery Hose Service

Details removing and installing the oil delivery hose, emphasizing the need for replacement if damaged during removal.

Chain Lubrication: Non-Adjustable Oil Pump

States that these pumps are not repairable and must be replaced if faulty, and mentions checking the worm.

Chain Lubrication: Adjustable Oil Pump Service

Covers removing and installing the adjustable oil pump, including checking the worm, ring, washer, and oil delivery hose.

Chain Lubrication: Tank Vent Valve Service

Explains the function of the tank vent valve and how to remove and install it if faulty.

Fuel System for STIHL MS 240, 260

Fuel System: Air Filter Maintenance

Discusses the impact of dirty air filters on engine power and starting, and when to check it.

Fuel System: Carburetor Removal and Installation

Details how to remove and install the carburetor, including air filter, fuel tank, and throttle rod disconnection.

Fuel System: Carburetor Removal and Installation (Continued)

Continues carburetor installation, covering sleeve, washer, carburetor position, impulse hose, and fuel hose connections.

Fuel System: Leakage Test Procedure

Explains how to perform a leakage test on the carburetor and check the tank vent.

Fuel System: Leakage Test Procedure (Continued)

Details the procedure for testing the carburetor with a pump and interpreting pressure readings.

Fuel System: Carburetor Servicing

Covers removing the carburetor, disconnecting the throttle rod, and servicing internal carburetor components.

Fuel System: Carburetor Servicing (Internal Components)

Details servicing the carburetor's end cover, gasket, diaphragm, and checking for damage or wear.

Carburetor Servicing: Inlet Needle

Explains how to remove, inspect, and install the inlet needle, control lever, and spring.

Carburetor Servicing: Fixed Jet

Covers removing and installing the fixed jet and checking it for damage.

Carburetor Servicing: Pump Diaphragm

Details removing and installing the pump diaphragm and gasket, including checking the fuel strainer.

Carburetor Servicing: Choke Shaft and Shutter

Mentions the choke shutter is in the air filter, referring to another section.

Carburetor Servicing: Adjusting Screws

Identifies the high speed, low speed, and idle speed screws and explains how to remove limiter caps.

Carburetor Adjustment: Basic Setting

Explains when a basic setting is needed and the procedure for carrying it out after removing the limiter cap.

Carburetor Adjustment: Basic Setting Procedure

Details the steps for performing the basic setting of the carburetor, including screw adjustments.

Carburetor Adjustment: Basic Setting Procedure (Continued)

Continues basic setting, including using screwdrivers, checking chain tension, and air filter.

Carburetor Adjustment: Standard Setting

Outlines the standard setting procedure for the carburetor, including engine warm-up and running checks.

Fuel System: Throttle Rod Service

Covers removing and installing the throttle rod, including disconnecting it from the trigger.

Throttle Rod: Intake Manifold Service

Details removing and installing the intake manifold, emphasizing inspection for damage.

Throttle Rod: Intake Manifold Service (Continued)

Continues intake manifold service, covering tank housing manipulation, string usage, and washer/ring fitting.

Intake Manifold: Impulse Hose Service

Explains how to remove and install the impulse hose, and check it for damage.

Fuel System: Tank Vent Testing

Describes how to test the tank vent by performing pressure and vacuum tests via the fuel hose.

Tank Vent Testing Procedure

Details the steps for testing the tank vent's function, including fuel draining and hose connection.

Tank Vent Removal and Installation

Covers removing and installing the tank vent, emphasizing the use of a new vent and proper seating.

Fuel System: Fuel Intake Components

Introduces fuel intake components like pickup body and suction hose, explaining their function and common issues.

Fuel Intake: Pickup Body Service

Explains how impurities clog the pickup body filter and how to clean or replace it.

Fuel Intake: Fuel Suction Hose Service

Details removing and installing the fuel suction hose, checking it for damage, and ensuring proper seating.

Fuel Intake: Tank Housing Removal and Installation

Covers removing and installing the tank housing, including handling mounting screws and annular buffers.

Heating System for STIHL MS 240, 260

Heating System: Carburetor Heating Function

Describes how the heating element is supplied with power and controlled by the thermostat.

Carburetor Heating: Complete System Test

Explains how to test the complete carburetor heating system, including temperature considerations.

Carburetor Heating: Heating Element Test

Details testing the heating element's resistance using an ohmmeter.

Carburetor Heating: Heating Element Test (Continued)

Continues testing the heating element, covering connection and insulation.

Carburetor Heating: Thermostatic Switch Service

Explains how to remove, install, and test the thermostatic switch.

Carburetor Heating: Thermostatic Switch Service (Continued)

Continues thermostatic switch service, focusing on test procedures and installation.

Carburetor Heating Troubleshooting

A flowchart to diagnose problems with the carburetor heating system based on resistance and switch tests.

Handle Heating System for STIHL MS 240, 260

Handle Heating System Troubleshooting

Identifies common faults in the handle heating system, such as circuit breaks or short circuits, and general checks.

Handle Heating System Troubleshooting (Continued)

Continues troubleshooting by checking resistance of components and using diagnostic charts.

Handle Heating: Heater Switch Service

Details removing and installing the heater switch and its associated ground wire.

Handle Heating: Heater Switch Service (Continued)

Continues heater switch service, covering grommet, connector, and positioning.

Heater Switch: Ground Wire Service

Explains how a faulty ground wire affects the heating system and how to check it.

Heater Switch: Ground Wire Service (Continued)

Continues ground wire service, covering terminal positioning and ensuring connections are secure.

Handle Heating: Rear Handle Heating Element Service

Details testing and replacing the heating element in the rear handle, including resistance checks.

Handle Heating: Rear Handle Heating Element Service (Continued)

Continues heating element installation, covering backing removal, element placement, and pressure pad fitting.

Handle Heating: Handlebar Heating Element Service

States that the front handlebar heating element is not replaceable and requires a new handlebar if faulty. Includes resistance testing.

Heating System: Generator Removal and Installation

Covers removing and installing the generator, including connector disconnection and checking for damage.

Heating System: Generator Removal and Installation (Continued)

Continues generator installation, covering magnet ring inspection, centering tool usage, and wire routing.

Handle Heating and Generator Troubleshooting Flowchart

A flowchart to diagnose handle heating and generator issues, guiding through switch, resistance, and component checks.

Handle Heating and Generator Troubleshooting Flowchart (Continued)

Continues troubleshooting, covering ground wire, handlebar heating element, and heater switch checks.

Handle Heating Test Values and Connections

Provides a table of ohmmeter connections, resistance specifications, and fault causes for troubleshooting.

Handle Heating Test Values and Connections (Continued)

Includes circuit diagrams for carburetor/handle heating and handle heating systems.

Wiring Harness Removal and Installation

Details removing and installing the wiring harness, including connector and tube management.

Wiring Harness Removal and Installation (Continued)

Continues wiring harness service, focusing on wire routing, insulation, and ensuring secure connections.

Wiring Harness Installation and Routing

Continues wiring harness installation, emphasizing proper wire routing and connector securing.

Special Servicing Tools for STIHL MS 240, 260

Servicing Aids for STIHL MS 240, 260

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