STIHL MS 500 I Service Manual

Overview and safety considerations

The STIHL MS 500 i is a high-performance chainsaw designed for demanding cutting tasks, requiring careful attention to safety and proper maintenance practices. Before any work, ensure you have a clear understanding of the machine’s operation, potential hazards, and the specific service procedures recommended by the manufacturer. A systematic approach to safety reduces the risk of injury and helps protect the tool’s longevity. Always verify that the power unit, bar, chain, and ignition system are appropriate for your application and local regulations. Proper preparation lays the foundation for a safe and effective service experience.

Personal protective equipment (PPE) is the first line of defense against injuries when operating or servicing a chainsaw. Equip certified cut-resistant gloves, hearing protection, eye protection with side shields, and a durable, snug-fitting long-sleeve garment. Steel-toed boots with non-slip soles provide stability on uneven surfaces, while a helmet with a visor adds protection from flying debris. In addition, use a chainsaw protective chaps or pants to shield your legs during handling and maintenance tasks. Adhering to PPE guidelines significantly lowers the chance of lacerations, impact injuries, and exposure to harmful materials.

Workspace setup is critical to safe servicing. Conduct work in a well-lit, well-ventilated area free of loose cords and clutter that could snag components or cause trips. Use a stable workbench or ergonomic stand and secure the saw in a vertical or horizontal position using a compatible vise or clamps. Keep a fire extinguisher within reach and ensure there is adequate space to maneuver tool components without risking contact with hot surfaces or moving parts. A clean, organized workspace minimizes the chance of misplacing parts and helps you follow the service steps with precision.

Chain saw safety fundamentals emphasize awareness of kickback, proper chain tension, and secure handling of the tool at all times. Always inspect the bar and chain for damage, wear, and proper lubrication before beginning any maintenance. Maintain a firm, balanced stance and keep both hands on the saw during operation and testing, if applicable. Understand the tool’s stopping mechanisms and emergency shutoff procedures, and never bypass safety features or operate a saw with a damaged safety guard. Clear communication with others in the vicinity is essential to prevent accidental starts and ensure that everyone remains at a safe distance during servicing.

When performing service procedures, follow a methodical sequence to avoid introducing new hazards. Disconnect the spark plug cap or remove the battery (for cordless models) to ensure there is no accidental ignition while servicing. Use the correct service tools and torque specifications, and refer to the manufacturer’s torque and calibration charts to avoid overtightening or under-tightening fasteners. Periodically verify that all safety features return to their intended positions after reassembly, and perform a cautious functional check in a controlled environment before resuming full operation. A deliberate, careful approach protects both the technician and the machine, delivering reliable performance over time.

Standard service tools and measurements for the STIHL MS 500 i include a comprehensive set of metric wrenches, sockets, feeler gauges, a torque wrench with appropriate ranges, hex keys, and a specialized chain oiling and tensioning gauge. Maintain a clean workspace and organize fasteners by size and type to prevent mix-ups during reassembly. When replacing the chain or bar, verify compatibility with the model’s guide bar length, chain pitch, and drive link count, ensuring correct chain tension as described in the service manual. Use calibrated measuring tools for cylinder and spark plug gaps, and always record service parameters for future reference. Accurate tools and careful measurement are essential to sustaining engine performance and overall tool reliability.

Product overview and specifications

The STIHL MS 500 i is a high-performance chainsaw engineered for demanding professional use, combining power, precision, and reliability in a compact package. It features a modern carbureted and electronic fuel delivery system designed to optimize fuel efficiency while delivering robust cutting ability in a variety of forestry tasks. The saw is built with a robust chassis, corrosion-resistant components, and thoughtful ergonomics to reduce operator fatigue during extended work sessions. Its design emphasizes balance and maneuverability, allowing precise control in tight or elevated cutting scenarios. Overall, the MS 500 i stands as a versatile tool suitable for felling, bucking, and limbing in mixed timber conditions, while maintaining a focus on safety and ease of maintenance for trained professionals.

Engine and fuel system specifications

The MS 500 i is driven by a high-output two-stroke engine that delivers substantial power-to-weight benefits, enabling efficient performance across a range of timber densities. The engine employs advanced electronic fuel injection to optimize air-fuel mixture, resulting in smoother throttle response, improved cold starts, and reduced emissions relative to traditional carbureted designs. A precision ignition system ensures reliable spark timing, contributing to consistent starting and running performance in challenging environments. The fuel system is designed to support long work intervals with minimal maintenance, incorporating durable lines, secure fittings, and easy-access components for routine inspections. Operating parameters such as maximum engine speed, idle speed, and recommended cutting thresholds are specified to align with safe, productive cutting practices and to protect the drive system from undue wear.

Fuel requirements for the MS 500 i emphasize fresh, high-quality two-stroke oil mixed with unleaded gasoline in an appropriate ratio as recommended by STIHL. The fuel delivery system is designed to reduce vapors and optimize combustion efficiency, contributing to lower fuel consumption and cooler exhaust temperatures. When refueling, operators should inspect the fuel filters and check for any signs of aging hoses or leaks, replacing components as needed to maintain consistent performance. Regular maintenance intervals for the fuel system include inspecting the fuel tank, checking the fuel lines for cracks, and ensuring that the carburetor or injection system remains free of obstruction. The combination of robust fuel delivery and precise engine timing helps ensure reliable performance even under load, making it suitable for professional-day workloads and extended cutting sessions.

Lubrication and chain brake systems

Lubrication in the MS 500 i is designed to maintain chain efficiency and minimize internal wear, with an adjustable oil pump that allows the operator to tailor lubricant delivery to the cutting conditions. Proper lubrication reduces heat buildup in the bar and chain, extends chain life, and helps maintain consistent cutting performance across different wood densities. The oil reservoir and pump assembly are designed for straightforward maintenance, with accessible ports for oil level checks and pump adjustments. It is important to use the correct grade of chain oil, as specified by STIHL, to ensure optimal viscosity and film strength under varying temperatures. Regular inspection of the oil lines and O-rings prevents leaks that could compromise lubrication and environmental safety.

The chain brake system on the MS 500 i is a critical safety feature that instantly immobilizes the chain in the event of kickback or operator withdrawal. The system is connected to the front handguard and engages through a mechanical linkage that activates the chain brake when the guard is pushed forward or if the inertia brake is triggered by a sudden deceleration. Proper adjustment ensures that the brake engages smoothly without causing unintended stops during normal operation, while maintaining rapid response in a kickback scenario. Routine inspection should verify the integrity of the brake band, linkage, and springs, ensuring there is no excessive wear or contamination that could impede braking performance. Regular testing and maintenance of the chain brake contribute significantly to operator safety and compliance with professional working standards.

Maintenance schedule and maintenance tasks

The STIHL MS 500 i requires a structured maintenance plan to ensure optimal performance, longevity, and safe operation. Establishing a routine maintenance interval based on usage, environmental conditions, and manufacturer recommendations helps prevent unexpected downtime and costly repairs. Begin with a clear record of dates and tasks completed, so you can track wear patterns and anticipate parts replacement before failure occurs. Regular inspection of critical safety features, such as the anti-vibration system, chain brake, and chain catcher, is essential alongside routine service items. This proactive approach keeps the saw performing at peak efficiency while maintaining a high level of operator safety.

Routine maintenance should be performed at defined intervals, taking into account how aggressively the saw is used. Light, occasional use may allow for longer intervals between air filter changes and spark plug inspections, whereas heavy or dusty environments require more frequent attention. Always consult the service manual for interval guidance tailored to your operating conditions. Keeping a clean machine and organized workspace accelerates the maintenance process and reduces the risk of overlooked components. A systematic checklist approach ensures that nothing is skipped and that every critical system is inspected during each service cycle.

Consider maintaining a service log that documents the mileage, hours of operation, and any anomalies observed. This log becomes a valuable diagnostic tool if performance deteriorates or an unusual vibration or noise appears. In addition to scheduled tasks, perform quick daily checks before starting the engine, such as verifying fuel levels, chain tension, and bar oil supply. Early detection of issues through these quick checks can prevent more serious problems and extend the life of the engine and cutting system. A well-maintained maintenance schedule supports safer operation, reduces downtime, and preserves the resale value of the equipment.

Air filters and the cooling system require particular attention due to their direct impact on engine longevity and performance. A clogged air filter reduces airflow, causing the engine to run lean and overheat, which can lead to accelerated wear or damage. Inspect the air filter at each maintenance interval and clean or replace it as recommended by STIHL. The cooling system, including the flywheel fins and surrounding shrouds, should be checked for debris that can impede heat dissipation. Remove dust, grass, and resin accumulations to maintain efficient cooling, especially after prolonged cutting sessions or in environments with fine particulates. Ensuring unrestricted airflow through the cooling system helps sustain power output and reduces the risk of overheating during demanding cutting tasks.

Fuel system inspection and care are crucial for consistent performance and reliable starts. Use fresh fuel mixed to the correct ratio with the appropriate oil for two-stroke engines, and store fuel in approved containers to prevent contamination. Check for leaks in hoses, seals, and the fuel line, and replace any damaged components promptly. Inspect the fuel filter for clogs and replace it per the manufacturer's schedule to maintain proper fuel flow. During maintenance, examine the carburetor and fuel lines for signs of wear or damage, and adjust the idle speed and mixture only if you have the proper tools and knowledge. Regularly cleaning the fuel system reduces the likelihood of hard starts, misfires, and power loss during heavy cutting jobs.

Lubrication system and bar maintenance are key to efficient cutting and long tool life. Ensure the bar oil delivery system is functioning correctly by verifying oil flow during operation, and check the oil reservoir level before each use. Inspect the bar and chain for wear, cracks, or missing drive links, and replace as necessary to prevent kickback or binding. Regularly sharpen and file the chain to maintain proper cutting efficiency and reduce the load on the engine. Lubricate the chain brake and bar mounting hardware according to the service schedule to prevent rust and ensure smooth operation. Proper lubrication and bar maintenance minimize friction, extend chain life, and keep cutting performance consistent across demanding tasks.

In addition to these core areas, pay attention to the spark plug condition, muffler screen, and anti-vibration system during each maintenance cycle. A fouled spark plug indicates improper combustion and can lead to hard starting or reduced power, while a damaged muffler screen can affect exhaust flow and noise levels. The anti-vibration system should be checked for wear or looseness that could impact control and operator comfort. Addressing these items promptly contributes to safe operation, precise control, and a more enjoyable cutting experience overall. Adhering to a comprehensive maintenance routine ensures the STIHL MS 500 i delivers reliable performance for years of demanding use.

Before initiating any disassembly or inspection, perform thorough safety checks to protect yourself and safeguard the equipment. Ensure the unit is cool to the touch and that all fuel has been drained or isolated to prevent spills and fires. Disconnect the spark plug boot to eliminate the risk of accidental ignition, and wear appropriate personal protective equipment, including eye protection, gloves, and hearing protection if the engine has been recently started. Place the saw on a stable work surface with the bar and chain secured to prevent unintended movement. Have all required tools ready and prepare a clean workspace to keep fasteners and components organized for accurate reassembly.

Carburetor and fuel system disassembly requires careful attention to avoid damage to delicate passages and seals. Start with removing the air filter housing and cleaning the surroundings to prevent contaminants from entering the carburetor. Take photos or make notes of hose and linkage routes before removing any components to ease reassembly. When detaching the carburetor, handle it gently to preserve the fuel inlet needle, diaphragm, and gasket surfaces. Inspect all fuel lines for cracks or signs of deterioration and replace any compromised parts. During reassembly, verify that the carburetor mounting surfaces are clean and free of residue, and ensure all fasteners are torqued to the manufacturer’s specifications to maintain proper seals and performance.

Ignition system and spark plug inspection require a systematic approach to diagnose misfires or weak performance. Begin by removing the ignition capacitor or ignition coil access cover if present, and check for corrosion or loose connections at the low and high voltage terminals. Use a feeler gauge or a dedicated timing tool if required by your model to verify ignition timing and advance settings, adjusting only within the specifications provided. Inspect the spark plug for electrode wear, fouling, or improper gap, and clean or replace as indicated by the condition. When reinstalling, ensure the spark plug is correctly gapped and torqued to the recommended value. Reconnect all electrical connections securely and test the ignition system with a diagnostic light or a proper test method to confirm reliable spark competency before attempting a full restart.

Bar, chain, and sprocket inspection and replacement demand precise measurement and careful handling to maintain cutting performance and safety. Remove the guide bar and chain assembly and inspect the bar rails for uneven wear, burrs, or twists, and measure the groove width to confirm it aligns with the chain pitch. Check the condition of the drive sprocket for hooked teeth, chips, or looseness in the sprocket bearing area, replacing it if excessive wear is evident. Inspect the chain for stretch, cracked rollers, bent drive links, or dull cutters, and verify proper tensioning guidelines according to the saw’s specification. When installing a new chain and bar, align the chain with the sprocket correctly and set tension according to the manual, ensuring smooth rotation with minimal side play. After reassembly, perform a controlled idle test and brief cut or pad test on a non-spark area to confirm that the chain tracks properly and that no abnormal noises or vibrations are present.

The reassembly process for the STIHL MS 500 i requires careful attention to order, cleanliness, and torque specifications to ensure optimal performance and safety. Begin by confirming all components are present and free of damage, and lay out a clean workspace with the correct tools. Reinstall major assemblies in the reverse order of disassembly, starting with the internal components and moving toward external housings. Apply the recommended torque values to fasteners as specified by the manufacturer, using a calibrated torque wrench to avoid under- or over-tightening. After each critical fastener is secured, perform a visual inspection to verify seating, alignment, and absence of interference with moving parts. Once the major assemblies are in place, reinstall ancillary components such as shields, covers, and brackets, ensuring all gaskets and seals are properly seated to prevent leaks. Finish with a functional check of the throttle trigger, stop, and linkage to confirm smooth operation before proceeding to carburetor tuning and ignition checks.

Reassembly sequence and torque guidelines emphasize accuracy and methodical progression. Start with the crankcase and essential engine internals, ensuring proper lubrication and cleanliness of mating surfaces. Sequentially mount the cylinder, piston, and connecting rod, following the exact orientation marks and timing considerations specified for the MS 500 i. Tighten all main bearing and connecting rod fasteners to the prescribed torque values, checking for any signs of binding or misalignment as components mate. Install the piston circlips and rings with correct orientation, and verify piston ring gaps are within tolerances. Refit the crankcase cover and any related gaskets, using the correct sequence of fasteners and ensuring even compression around the mating surfaces. Reassemble the carburetor mounting hardware, fuel lines, and vacuum connections only after confirming that the intake path is clear and free of obstructions.

Carburetor setup and tuning require careful calibration to balance fuel delivery with air intake for peak performance. Start by connecting the correct fuel and oil mixtures as specified in the manual, ensuring there are no leaks at fuel lines or fittings. Synchronize the throttle linkage to ensure symmetrical movement and consistent return to idle when released. Adjust the low, mid, and high-speed needle adjustments according to the manufacturer’s recommended baseline, then perform incremental fine-tuning while the engine is under light load. Monitor engine response, noting RPM stability, acceleration, and any signs of hesitation or without-load surging. Record final settings and verify that the carburetor screws are locked or secured as required to prevent vibration-induced changes. After tuning, recheck all fuel-related connections for leaks and confirm that the air intake is unobstructed.

Ignition system checks after reassembly focus on timing, spark quality, and trigger integrity. Inspect the ignition module, coil, and kill switch wiring for secure connections and proper insulation. Use a timing light to verify the ignition timing aligns with the MS 500 i specifications, adjusting as necessary within the serviceable range. Confirm the spark plug is the correct type and condition, with a clean gap and no fouling that could indicate fuel or oil issues. Perform a dynamic test by cranking the engine at a safe speed to listen for consistent spark and smooth ignition transitions across different throttle positions. Ensure the shutdown mechanism functions reliably and that there is no inadvertent grounding or short circuits. After validating the ignition system, perform a final inspection of wiring harnesses, connectors, and protective shields to prevent interference with moving parts.

Bar and chain installation and tensioning require precise alignment and tension to ensure safe operation and effective cutting performance. Begin by mounting the bar onto the chassis, aligning it with the clutch cover and drive sprocket to prevent misalignment during operation. Thread the chain onto the bar carefully, ensuring the drive links mesh correctly with the sprocket and that the depth gauge faces are oriented properly. Apply the correct chain tension with the bar in a level position and the chain resting snugly against the bar but with a small amount of slack when the chain is engaged in a safe test. Use the recommended tension values from the STIHL service manual and recheck tension after the saw has reach operating temperature. Install the bar nuts and ensure they are tightened to the specified torque with the bar mounted flush against the mounting surface. Finally, perform a functional test by rotating the chain manually to confirm smooth operation and absence of binding, then recheck chain tension after a brief run to ensure stability.

Troubleshooting and fault diagnosis

Common starting problems and solutions: When a STIHL MS 500 I fails to start, begin with a systematic check of the basics. Verify that the fuel is fresh and correctly mixed, with the proper oil-to-fuel ratio, and inspect the fuel filter for blockages. Ensure the air filter is clean and free of debris, as a restricted intake can hamper starting performance. Check the spark plug for signs of fouling, wear, or improper gap, and replace it if necessary. Confirm that the relay and kill switch are functioning correctly and that the choke mechanism operates smoothly. If the unit still won’t start, perform a compression check to determine whether the internal engine components are sealing properly, and inspect for air leaks around the carburetor boots and intake manifold. A thorough inspection of the spark plug boot connection and wiring can reveal intermittent ignition problems that prevent a reliable start.

Power loss and performance troubleshooting: When cutting performance deteriorates or the saw loses power under load, begin by examining the air intake for obstructions and the muffler for carbon buildup, as restricted flow reduces performance. Check the fuel system for signs of varnish or contamination in the carburetor jets, and clean or rebuild the carburetor if necessary. Inspect the ignition system for a consistent spark under load, as weak ignition can mimic fuel issues. Examine the exhaust port and spark arrestor screen for blockages that can cause back pressure and performance drops. Finally, verify that the anti-vibration mounts are secure and that the chain brake is fully disengaged, as inadvertent engagement or loose components can affect power delivery and cutting efficiency.

Excessive vibrations and noise diagnosis: Excessive vibrations can indicate issues with the bar and chain combination or with engine mounting. Start by inspecting the bar for square, straight wear and ensuring the chain properly lubricates; a dull or damaged chain can cause uneven cutting and vibration. Align and tension the chain according to the manufacturer’s specifications, ensuring that the brake band and clutch side cover are intact and properly seated. Inspect the clutch drum, sprocket, and drums for wear or damage, as a failing clutch can introduce unusual vibration patterns and noise. Check the engine mount bolts and anti-vibration springs for loosening or fatigue, replacing any worn components. If abnormal noise persists, isolate the source by listening at the muffler, bar tip, and clutch area to determine whether a bearing, gear, or missing fastener is contributing to the sound.

Safety system malfunctions and remedies: Safety systems are critical for preventing injuries, so address any faults promptly. If the chain brake engages unexpectedly, verify that the brake linkage and stop switch operate freely and return to their neutral positions when released. Inspect the throttle trigger lockout and stop switch wiring for signs of wear or short circuits, and repair or replace damaged insulation as needed. A malfunctioning chain catcher or hand guard should be inspected and replaced to prevent injury in the event of a kickback. If the low-oil or chain oiling alarms activate without cause, check the oil supply lines, pump, and filter for blockages, and confirm the oil’s viscosity and compatibility with operating temperature. In all cases, consult the service manual for torque specifications on fasteners and perform a controlled test operation in a safe environment after completing any repairs.

Repair and part replacement guidance

In STIHL MS 500 i service work, accurate parts identification is essential to ensure proper fit and reliable operation. Begin by consulting the model and serial numbers etched on the powerhead to verify compatibility with genuine STIHL replacement components. Use the official parts catalog or authorized dealer databases to cross-reference part numbers, avoiding aftermarket substitutions that could affect performance or safety. When sourcing parts, prioritize new or completely refurbished items from reputable suppliers, and inspect packaging for integrity to prevent moisture or corrosion during storage. Maintain meticulous records of each replacement, including part numbers, procurement date, and the corresponding service performed to support future maintenance planning and warranty compliance.

Gasket and seal replacement procedures require careful handling to preserve engine integrity. Before disassembly, depressurize the fuel system and remove the spark plug to prevent accidental cranking. When removing gaskets and seals, keep accompanying hardware organized to ensure correct reassembly, as improper alignment can lead to leaks or restricted lubrication. Clean mating surfaces thoroughly with a non-abrasive solvent and a lint-free cloth, inspecting for grooves or warping that may necessitate surface resurfacing or component replacement. Install new gaskets and seals with the appropriate torque values and straight, even seating to maintain a proper seal under operating temperatures and vibration. Finally, perform a controlled leak check after assembly to verify sealing integrity before returning the machine to service.

Clutch and drive system service demands careful inspection of all rotating components and their supporting bearings. Remove the clutch cover and inspect the drum, shoes, and springs for wear, glazing, or cracks, replacing any fatigued or damaged parts. Check the drive sprocket, chain, and anti-rotation devices for excessive play or misalignment, and replace worn teeth or links as needed. When servicing bearings, wash or replace them according to the manufacturer’s guidelines, ensuring proper lubrication with the specified grease or oil. Reassemble with the correct orientation and verify smooth operation through manual rotation before reinstalling the cover and performing a test run. Regular inspection of tension, alignment, and balance in the drive system helps prevent premature failure and maintains efficient power transfer to the chain.

Exhaust and muffler maintenance is critical for both performance and emissions control. Inspect the muffler for holes, cracks, or clogging from carbon buildup, and remove any loose studs or mounting hardware with appropriate tools. Clean internal baffling and exhaust ports, taking care not to damage heat shields or gasket surfaces. Replace damaged gaskets, seals, and mounting hardware with OEM parts to ensure proper exhaust flow and heat management. When reassembling, reseat the muffler securely and torque fasteners to the specification provided by STIHL, verifying that there are no exhaust leaks. Periodic inspection of the exhaust system can improve engine efficiency, reduce noise, and extend engine life by maintaining optimal backpressure and scavenging behavior under load.

Storage, transport, and end of life considerations

Proper storage of the STIHL MS 500 i chainsaw is essential to maintain fuel integrity, engine health, and bar/chain condition. Fresh fuel should be stored in approved, labeled containers away from heat sources and direct sunlight, ideally in a cool, dry place with good ventilation. Before long-term storage, run the engine until the fuel is depleted or add a suitable fuel stabilizer to prevent varnish buildup in the carburetor and fuel system. Clean all exterior surfaces to remove sap, oil, and debris, and ensure the chain is dulled or removed to prevent accidental contact during handling. This preparation helps prevent corroded components, gasket damage, and starting difficulties when the tool is returned to service.

For temporary storage, keep the saw in a secure, upright position with the bar and chain cleared of contact with the ground or other objects. Loosen the bar nuts slightly to relieve chain tension if the saw will be stored for an extended period, then re-tighten before use. Protect the air intake and cooling fins from dust and moisture by covering the housing or placing the saw in a protective case. When storing between projects, verify that there is no liquid fuel leakage and ensure that the spark plug boot remains firmly connected to prevent moisture ingress into the ignition system. These steps minimize the risk of corrosion, fuel leaks, and difficulty starting after storage breaks.

Transport safety precautions are critical to prevent accidents and maintain the integrity of the STIHL MS 500 i during movement. Transport the saw in a dedicated case or sturdy tool bag, with the chain covered by a scabbard to avoid accidental contact. Keep fuel and oil separate from heat sources, ignition sources, and passengers, and ensure only trained personnel handle the equipment. When lifting or loading, use proper lifting techniques to protect your back and use a secure strap or rack to prevent shifting during transit. Confirm that ignition switch is off, the chain brake is engaged, and the engine is cool before loading or unloading. Observing these precautions reduces the risk of injury and damage to the machine or surrounding property.

Waste disposal and environmental considerations require responsible handling of fluids, consumables, and worn parts. Used oil, fuel, and hydraulic fluids must be collected in appropriate containers and disposed of at approved recycling or hazardous waste facilities in accordance with local regulations. Reusable or recyclable components, such as filters and metal parts, should be sorted and prepared for recycling where feasible, while non-recyclable components must be disposed of per environmental guidelines. Filtration materials, rubber seals, and contaminated absorbents should be treated as hazardous waste if contaminated with fuel or oil. When replacing worn components, consult the service guide for proper torque specifications and disposal guidelines to minimize environmental impact and maintain compliance with emission and safety standards.