Welcome to the STIHL MS 251 manual, your comprehensive guide to safe and effective chainsaw operation. This manual provides essential information for optimal performance and maintenance;
Overview of the STIHL MS 251 Chainsaw
The STIHL MS 251 is a high-performance chainsaw designed for demanding tasks. It features a powerful two-stroke engine with electronic magneto ignition and a diaphragm carburetor for reliable starts. The saw is equipped with a robust chain brake system that stops the chain in fractions of a second, enhancing safety. Weighing just over 10 pounds, it combines portability with strength, making it ideal for logging, firewood cutting, and landscaping. The MS 251 also includes features like the Easy2Start system and a manual fuel primer, simplifying operation. Its compact design and ergonomic controls ensure comfort during extended use, while the high-torque engine delivers consistent cutting performance. This chainsaw is built for professionals and homeowners seeking durability and efficiency in a versatile tool.
Importance of Reading the Manual
Reading the STIHL MS 251 manual is crucial for safe and effective operation. It provides detailed instructions on starting, stopping, and maintaining the chainsaw, ensuring optimal performance and longevity. The manual explains safety symbols, reactive forces, and kickback prevention, which are essential for preventing accidents. It also covers troubleshooting common issues and diagnostic steps, helping users resolve problems quickly. By understanding the technical specifications, such as engine type and fuel systems, users can make informed decisions. Additionally, the manual highlights proper storage and transportation guidelines to maintain the saw’s condition. Adhering to the manual’s guidelines ensures compliance with safety standards and warranty requirements, making it indispensable for both novice and experienced users.
Safety Precautions
Always follow safety guidelines to minimize risks. Understand reactive forces, prevent kickback, and use proper PPE. Adhere to manual instructions for safe operation and maintenance procedures.
Understanding Safety Symbols
Safety symbols are crucial for quick comprehension of potential hazards. The STIHL MS 251 manual uses standardized pictograms to alert users to dangers like kickback or moving parts. These symbols, often accompanied by explanations, ensure clear communication regardless of language. Warning triangles with exclamation marks indicate general caution, while specific icons highlight risks like rotating chains or hot surfaces. Understanding these symbols is essential for safe operation, as they provide instant visual warnings. Always refer to the manual for detailed explanations of each symbol to ensure proper interpretation and adherence to safety guidelines. Familiarize yourself with these icons to minimize risks and operate the chainsaw safely and effectively.
Reactive Forces and Kickback Prevention
Reactive forces, including kickback, pose significant risks during chainsaw use. Kickback occurs when the chain’s upper tip strikes an object, causing the saw to jolt backward. The STIHL MS 251 manual emphasizes preventing kickback through proper technique and equipment. Ensure the chain is sharp and correctly tensioned, as dull chains increase kickback risk. Maintain a firm grip with both hands and avoid cutting with the upper tip. Use protective gear, including gloves and safety glasses. The saw’s chain brake can stop the chain in emergencies. Familiarize yourself with these precautions to minimize hazards and maintain control. Regular maintenance and adherence to safety guidelines are vital for safe operation and injury prevention. Always follow the manual’s recommendations to handle reactive forces effectively.
Personal Protective Equipment (PPE)
Protecting yourself with proper Personal Protective Equipment (PPE) is crucial when operating the STIHL MS 251 chainsaw. Always wear safety glasses or goggles to shield your eyes from debris. A face shield or mesh visor offers additional protection. Hearing protection, such as earplugs or earmuffs, is essential to prevent noise-induced hearing loss. Wear sturdy gloves to improve grip and protect your hands from cuts and abrasions. Durable, chainsaw-resistant pants or chaps are recommended to safeguard your legs. Steel-toed boots with good traction provide stability and foot protection. Ensure all PPE meets safety standards and is in good condition. Wearing the right gear significantly reduces injury risks, allowing you to operate the saw confidently and safely. Always prioritize PPE as part of your pre-operation routine.
Technical Specifications
The STIHL MS 251 features a powerful two-cycle engine with electronic magneto ignition and a diaphragm carburetor, designed for optimal performance and fuel efficiency in various cutting conditions.
Engine Type and Performance
The STIHL MS 251 is equipped with a high-performance two-stroke engine, delivering reliable power for cutting tasks. Its electronic magneto ignition ensures consistent starts, while the diaphragm carburetor optimizes fuel flow for efficient combustion. Designed for durability, the engine features a robust construction to withstand heavy use. With a focus on reduced emissions, the MS 251 adheres to environmental standards while maintaining superior cutting performance. Proper maintenance, as outlined in this manual, will ensure the engine continues to perform at its best, providing years of dependable service for professionals and homeowners alike.
Ignition and Fuel System
The STIHL MS 251 features an electronic magneto ignition system, ensuring reliable and consistent engine starts. The fuel system is equipped with an all-position diaphragm carburetor, which provides optimal fuel flow regardless of the saw’s orientation. This design enhances performance and reduces the risk of fuel starvation during operation. The carburetor is designed to maintain the correct air-fuel mixture, contributing to efficient combustion and reduced emissions. Proper maintenance of the ignition and fuel systems, as outlined in this manual, is crucial for maintaining peak performance and longevity of the engine. Regular cleaning and inspection of these components will help ensure smooth operation and reliable cutting power.
Chain Brake and Safety Features
The STIHL MS 251 is equipped with a chain brake system that stops the saw chain in a fraction of a second when activated. This critical safety feature helps prevent accidents and injuries, particularly during kickback situations. The chain brake is activated by a manual lever or handle, which engages a metal brake that halts the chain’s movement immediately. Proper use of the chain brake is essential for safe operation, and this manual provides detailed instructions on how to activate and maintain it. Regular inspection of the chain brake mechanism is recommended to ensure optimal performance and reliability. This feature, combined with other safety mechanisms, makes the MS 251 a reliable choice for professionals and homeowners alike. Always review the manual for proper activation and maintenance procedures.
Operating Instructions
Follow detailed guidelines for starting, stopping, and using the chain brake. Proper techniques ensure safe and efficient operation of your STIHL MS 251 chainsaw.
Starting the Engine
To start the STIHL MS 251 engine, ensure the chain brake is engaged and the saw is on a flat, stable surface. Flip the emergency stop switch to the “on” position and move the master control lever to the “start” position. For a cold start, push the choke lever fully forward. Pull the starter rope slowly until resistance is felt, then pull sharply. Once the engine coughs, push the choke lever back to the “run” position and allow the engine to warm up. For a warm start, the choke lever should remain in the “run” position. Always follow proper starting procedures to ensure safe and reliable engine operation. Consult the manual for detailed instructions if issues arise.
Stopping the Engine
To stop the STIHL MS 251 engine, first disengage the throttle by releasing the trigger. Next, flip the emergency stop switch located on the top of the chainsaw to the “stop” position. This will immediately shut off the engine. For additional safety, ensure the chain brake is engaged before stopping the engine. Once the engine has stopped, move the master control lever to the “stop” position to prevent accidental restarts. Always allow the engine to cool slightly before storing or transporting the chainsaw. If the engine is hot, wait a few minutes to avoid potential damage. Properly stopping the engine ensures safe operation and extends the lifespan of your chainsaw. Always follow these steps to maintain safety and functionality.
Using the Chain Brake
The chain brake on the STIHL MS 251 is a critical safety feature designed to stop the saw chain in a fraction of a second. To engage the chain brake, firmly push the brake handle forward until it clicks into place. This action halts the chain immediately, even if the engine is still running. The brake can also activate automatically in the event of a kickback, thanks to its inertia-driven mechanism. Always ensure the chain brake is disengaged before starting the engine or resuming cutting. When not in use, keep the chain brake engaged for added safety. Proper use of the chain brake is essential for preventing accidents and maintaining control of the chainsaw during operation. Regularly check the brake’s function to ensure it operates smoothly and effectively.
Maintenance and Servicing
Regular maintenance ensures optimal performance and longevity. Clean the air filter, inspect the chain, and check the bar. Proper storage and transportation are essential for safety and durability.
Regular Maintenance Tasks
Regular maintenance is crucial for the optimal performance and longevity of your STIHL MS 251 chainsaw. Daily checks should include inspecting the chain for sharpness and wear, ensuring proper tension, and cleaning the guide bar. The air filter must be cleaned or replaced regularly to maintain engine efficiency. Additionally, check the muffler for debris and ensure the chain brake functions correctly. Every 50 hours of use, replace the spark plug and check the ignition system. Proper lubrication of moving parts and regular fuel system maintenance are also essential. Follow the manufacturer’s guidelines for oil and fuel ratios to ensure smooth operation.
Chain and Bar Maintenance
Proper maintenance of the chain and bar is essential for the STIHL MS 251 chainsaw’s performance and longevity. Regularly inspect the chain for sharpness and wear, ensuring it is properly tensioned to avoid damage. Clean the guide bar and check for any debris or buildup that could interfere with the chain’s movement. Lubricate the bar and chain frequently to reduce friction and prevent overheating. Sharpen the chain according to the manufacturer’s guidelines, and replace it when worn beyond repair. Additionally, ensure the bar is aligned correctly and free from damage. Regular cleaning and lubrication will extend the life of both the chain and bar, ensuring optimal cutting efficiency and safety.
Storage and Transportation
When storing the STIHL MS 251 chainsaw, ensure it is placed in a dry, secure location out of reach of children. Drain the fuel tank or use a fuel stabilizer to prevent degradation. Clean the saw thoroughly, paying attention to the chain and bar, to avoid rust and corrosion. Use a protective cover to shield it from dust and moisture. For transportation, always use a sturdy, enclosed container or bag to prevent accidental activation. Ensure the chain brake is engaged and the chain is properly secured. Follow local regulations for transporting hazardous materials, as the saw may contain fuel or oil. Proper storage and transportation will help maintain the chainsaw’s performance and longevity while ensuring safety.
Troubleshooting
Troubleshooting helps identify and resolve common issues with the STIHL MS 251, such as engine problems or chain malfunctions, ensuring optimal performance and safety.
Common Issues and Solutions
Common issues with the STIHL MS 251 include the chain not moving, engine not starting, or poor cutting performance. If the chain stops, check if the chain brake is activated. For engine issues, ensure proper fuel mixture and spark plug condition. If the chain is loose or damaged, adjust or replace it. Fuel system problems may require cleaning or replacing the air filter. Regularly check and maintain the chain tension for optimal performance. If the saw is hard to start, ensure the choke is functioning correctly. Refer to the manual for diagnostic steps and solutions to ensure safe and effective operation.
Diagnostic Steps
To diagnose issues with the STIHL MS 251, start by identifying symptoms. If the chain stops abruptly, check the chain brake activation. For engine issues, inspect the fuel system, spark plug, and air filter. Ensure proper fuel mixture and ignition. If the saw vibrates excessively, check the chain tension and bar alignment. For cutting performance problems, verify the chain sharpness and adjust the chain tension. Refer to the manual for specific diagnostic procedures and safety guidelines. Always follow proper techniques to identify and address issues effectively. Regular diagnostics help maintain performance and extend the tool’s lifespan.
Proper use and maintenance ensure the STIHL MS 251 operates safely and effectively. Always follow manual guidelines for optimal performance and longevity of your chainsaw.
Final Tips for Safe and Effective Use
Always perform regular maintenance tasks, such as chain sharpening and bar lubrication, to ensure optimal performance. Use proper cutting techniques and avoid situations that may cause kickback. Wear personal protective equipment, including gloves, safety glasses, and a helmet, every time you operate the chainsaw. Keep the chain brake in good condition and test it before use. Store the saw in a dry, secure location, and transport it with the chain covered. Follow the recommended fuel and lubricant specifications to maintain engine health. By adhering to these guidelines, you can maximize the lifespan of your STIHL MS 251 and ensure safe, efficient operation.