The Stihl FS 251 is a rugged, high-performance brushcutter built for professionals who need to move from heavy grass to woody stalks. As the successor to the legendary FS 250, the FS 251 features an updated 2-MIX engine that provides more torque with lower emissions.
This guide provides a comprehensive list of replacement parts for the FS 251. Because this machine shares a platform with the Stihl FS 240, many of the internal engine and drive components listed below are cross-compatible between these two models.
Models Sharing Parts with the Stihl FS 251:
- Stihl FS 240 / FS 240 R: Most engine, filtration, and fuel components are identical.
- Stihl FS 260: Shares some heavy-duty gearbox and drive tube components.
- Stihl FS 250: Note: Only the gearbox and some handle components are shared; engine parts are generally not interchangeable.
I. Engine Components
The FS 251 engine is designed for high-endurance clearing. Keeping the compression and exhaust clear is key to longevity.
| Component | OEM Part Number |
| Cylinder with Piston (40mm) | 4128 020 1211 |
| Piston Rings (Set of 2) | 4128 034 3001 |
| Crankshaft Assembly | 4128 030 0400 |
| Muffler Assembly | 4128 140 0601 |
| Spark Arrestor Screen | 4128 141 9001 |
| Cylinder Gasket | 4128 029 2301 |
II. Fuel & Air System
Proper filtration is the first line of defense against engine failure. The FS 251 uses a high-capacity pleated air filter.
- Air Filter (Pleated Paper): 4147 141 0300
- Air Filter Cover: 4148 141 0500
- Carburetor (Complete): 4128 120 0607
- Carburetor Repair Kit: 1129 007 1062
- Fuel Filter (Pickup Body): 0000 350 3500
- Fuel Tank Cap (Toolless): 0000 350 0533
- Primer Bulb: 4133 121 2700
III. Ignition & Starter System
Stihl’s ignition modules are solid-state, but the wiring and starter components are subject to daily wear and tear.
- Ignition Module (Coil): 4128 400 1306
- Spark Plug (NGK BPMR7A): 0000 400 7000
- Rewind Starter Assembly: 4128 190 4001
- Starter Pawl Kit: 4128 007 1000
- Rewind Spring: 4128 190 0600
- Starter Rope (3.0mm): 0000 190 2900
IV. Clutch & Drive System
The gearbox transfers the engine’s power to the cutting head. Regular greasing of these gears is the most overlooked maintenance task.
| Component | OEM Part Number |
| Clutch Drum | 4128 160 2900 |
| Clutch Shoe Assembly | 4128 160 2001 |
| Gearbox (Complete Drive Head) | 4128 640 0125 |
| Thrust Washer | 4130 713 1600 |
| Rider Plate (Protective) | 4128 713 3100 |
| Collar Nut (Left Hand Thread) | 4126 642 7600 |
| Gearbox Grease (80g) | 0781 120 1109 |
V. Handles & Guards
Ergonomics are vital for long days in the field. Ensure your throttle and harness connections are in top shape.
- Throttle Cable (Bike Handle): 4128 180 1112
- Throttle Cable (Loop Handle): 4128 180 1104
- Stop Switch: 4128 430 0200
- Universal Deflector (Guard): 4119 710 8103
- Loop Handle (FS 251 R): 4130 790 1316
How to Ensure a Perfect Fit
When ordering parts for your FS 251, always verify your serial number. Because this model shares a significant number of components with the FS 240, you may occasionally see parts labeled for both models; this is normal and indicates the cross-compatibility of the 2-MIX platform. Always choose OEM Stihl parts when possible to maintain the balance and timing of the high-torque engine.
By keeping this list handy and performing regular maintenance, you can ensure your Stihl FS 251 remains the most reliable tool in your landscaping arsenal.