The STIHL MS 251 is a reliable chainsaw designed for efficient cutting tasks. It features a powerful two-cycle engine and advanced safety mechanisms. This manual provides essential guidance for safe operation, maintenance, and troubleshooting, ensuring optimal performance and user safety.
1.1 Overview of the STIHL MS 251 Model
The STIHL MS 251 is a high-performance chainsaw designed for demanding cutting tasks. It features a robust two-cycle engine, advanced ignition system, and ergonomic design. The model includes versions like the MS 251 C-BE, equipped with innovations such as Quick Chain Adjuster and Easy2Start. Its compact design and powerful performance make it ideal for logging, firewood cutting, and professional use, ensuring efficiency and reliability in various applications.
1.2 Key Features and Benefits
The STIHL MS 251 boasts a high-torque two-cycle engine, delivering strong performance for demanding tasks. It includes features like the Easy2Start system for effortless starting and a side-access chain tensioner for quick adjustments. The advanced ignition system ensures reliable operation, while the reduced-emission technology minimizes environmental impact. These features make the MS 251 a versatile and efficient tool for professionals and homeowners alike, ensuring precise cuts and long service life.
1.3 Importance of the Instruction Manual
The instruction manual is crucial for safe and effective operation of the STIHL MS 251. It provides detailed guidance on safety precautions, proper usage, and maintenance procedures. Following the manual ensures compliance with safety standards, prevents accidents, and extends the saw’s lifespan. Always read and understand the manual before using the chainsaw to maximize performance and minimize risks associated with operating powerful cutting tools.
Safety Precautions and Pictograms
Safety is crucial when operating the STIHL MS 251. The manual explains pictograms, which indicate hazards and safe practices. Always wear recommended protective gear and follow transport guidelines to prevent accidents.
2.1 Understanding Pictograms on the Machine
The STIHL MS 251 features various pictograms to ensure safe operation. These symbols, found on the machine, warn of potential hazards and provide operational guidance. They include warnings for sharp cutting edges, proper handling, and protective equipment use. Understanding these pictograms is essential to prevent accidents and ensure compliance with safety standards. Always refer to the manual for detailed explanations of each symbol to maintain a safe working environment.
2.2 Personal Protective Equipment Recommendations
Using the STIHL MS 251 requires proper personal protective equipment to minimize injury risks. Always wear a helmet with face protection, safety glasses, and ear protection to guard against debris and noise. Durable gloves improve grip and control, while sturdy boots provide stability. The manual strongly recommends wearing certified protective gear at all times during operation to ensure safety and compliance with industry standards.
2.3 Transport Safety Guidelines
Always follow transport safety guidelines to prevent accidents. Before moving the chainsaw, ensure the engine is switched off, the chain brake is engaged, and the chain is covered with the scabbard. This prevents unintended chain movement. Secure the saw firmly during transport to avoid shifting or damage. These precautions minimize risks and ensure compliance with safety standards, protecting both the operator and others nearby.
Technical Specifications and Engine Details
The STIHL MS 251 features a high-performance two-cycle engine, designed for efficiency and durability. Its robust construction ensures reliable operation, making it ideal for demanding cutting tasks.
3.1 Two-Cycle Engine Overview
The STIHL MS 251 is equipped with a powerful two-cycle engine, delivering high torque and efficient fuel consumption. This lightweight design ensures easy maneuverability while maintaining robust performance, making it suitable for various cutting applications. The engine’s electronic ignition system enhances reliability, providing consistent starts and optimal combustion. Proper maintenance, as outlined in the manual, is essential to ensure the engine’s longevity and peak performance. Regular servicing and correct fuel mixture use are critical for sustained efficiency and power.
3.2 Ignition and Fuel Systems
The STIHL MS 251 features an electronic magneto ignition system, ensuring reliable starts and consistent engine performance; The fuel system includes an all-position diaphragm carburetor, designed for optimal fuel delivery in various operating conditions. Proper fuel mixture, as specified in the manual, is essential for maintaining engine health and efficiency. Regular maintenance of the fuel system, including cleaning and adjusting the carburetor, is crucial for preventing issues and ensuring smooth operation.
3.3 Chain Brake and Reactive Forces
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 safety feature reduces the risk of injury from reactive forces, such as kickback. Proper handling and awareness of kickback scenarios are emphasized in the manual to ensure safe operation. The chain brake is a critical component for mitigating risks associated with chainsaw use, making it essential to understand and utilize this system effectively.
Operating the Chainsaw
Operating the STIHL MS 251 requires following safe starting procedures, using proper cutting techniques, and ensuring safe stopping methods. Always adhere to the manual’s guidelines for optimal performance and safety.
4.1 Starting the Engine
To start the STIHL MS 251, ensure the chain brake is engaged and the saw is on a level surface. Prime the fuel system by pressing the primer bulb firmly. Move the choke to the “start” position and pull the starter handle gently until resistance is felt. Release, then pull firmly to start the engine. Once running, transition the choke to the “run” position for smooth operation. Always wear safety gear and follow manual guidelines.
4.2 Cutting Techniques and Best Practices
Always maintain control and proper footing while cutting. Keep the chainsaw at a comfortable cutting angle and apply steady, even pressure. Use the saw’s weight to assist in cutting, avoiding forced pressure. Ensure the chain is sharp and well-lubricated for efficient performance. Keep bystanders at a safe distance and avoid cutting in tight spaces. Follow the manual’s guidelines for specific cutting techniques and safety recommendations to achieve optimal results and minimize risks.
4.3 Stopping the Engine Safely
To stop the engine safely, first stop the chain by activating the chain brake. Move to a safe, open area away from obstacles and bystanders. Release the throttle and allow the engine to idle briefly. Then, switch off the ignition. Always ensure the chain has stopped completely before setting the saw down. Never leave the chainsaw unattended while it is running. Follow these steps to prevent accidents and ensure proper shutdown.
Maintenance and Servicing
Regularly check and adjust the chain tension to ensure proper cutting efficiency and safety. Sharpen the chain using the correct tools and techniques to maintain optimal performance.
5.1 Chain Tension and Sharpening
Regular chain tension adjustment is crucial for optimal performance and safety. Proper tension prevents chain derailment and ensures efficient cutting. Use the provided tool to tighten or loosen the chain as needed. Sharpening the chain regularly is essential to maintain cutting efficiency and prolong its lifespan. Always use the correct file size and technique to avoid damaging the chain teeth. Properly maintained chains reduce wear on the saw and improve overall productivity. Always refer to the manual for specific guidance on tensioning and sharpening procedures.
5.2 Lubrication and Filter Maintenance
Regular lubrication of the chain and guide bar is essential for smooth operation and longevity. Use STIHL chain oil, ensuring the reservoir is filled adequately. Check the oil level before each use and refill as needed. Clean or replace the air filter periodically to maintain proper engine performance. A dirty filter can reduce power and efficiency. Refer to the manual for specific lubrication intervals and filter maintenance instructions to ensure optimal functionality and extend the saw’s lifespan. Proper upkeep prevents overheating and wear.
5.3 Regular Servicing Schedule
Regular servicing ensures the chainsaw operates efficiently and safely. Check chain tension and sharpen it as needed. Lubricate the chain and bar regularly, and clean or replace the air filter. Inspect the spark plug and muffler for wear or damage. Follow the manufacturer’s recommended schedule for oil changes and component replacements. Neglecting routine maintenance can lead to reduced performance or engine damage. Always refer to the manual for specific servicing intervals and procedures to maintain optimal functionality and extend the saw’s lifespan.
Troubleshooting Common Issues
The manual provides solutions for common issues like chain stoppage or engine failure. Refer to the troubleshooting section for detailed diagnostics and repair guidance.
6.1 Chain Stops During Operation
If the chain stops during operation, check for a dull or damaged chain, incorrect tension, or debris obstruction. Sharpen or replace the chain, adjust tension, and ensure the area is clear. Regular maintenance helps prevent such issues. Always refer to the manual for specific guidance on troubleshooting and maintaining your STIHL MS 251 chainsaw for optimal performance and safety.
6.2 Engine Does Not Start
If the engine does not start, check for stale fuel, incorrect fuel mixture, or a blocked air filter. Ensure the spark plug is clean and properly gapped. Verify the ignition system is functioning and the choke is set correctly. Consult the manual for detailed troubleshooting steps. Regular maintenance, such as cleaning the air filter and ensuring proper fuel storage, can help prevent starting issues with your STIHL MS 251 chainsaw.
6.3 Other Common Problems and Solutions
Common issues include a blocked chain, dull chain, or faulty ignition. Check for debris in the chain and bar, sharpen or replace the chain as needed. Ensure proper chain tension and lubrication. If the ignition fails, inspect the spark plug and ignition coil. Regular cleaning of air filters and fuel system maintenance can prevent such issues. Always refer to the manual for detailed solutions and maintenance schedules to ensure optimal performance of your STIHL MS 251 chainsaw.