OEM C1M-S207 Carburetor Instruction Manual

1. Introduction

This manual provides detailed instructions for the installation, operation, maintenance, and troubleshooting of the C1M-S207 Carburetor. This carburetor is designed as a replacement part for various Stihl string trimmer models.

Compatible Stihl Models:

• FS40
• FS50
• FS56
• FS70
• KM56

2. Safety Information

Always prioritize safety when working with power tools and fuel systems. Failure to follow safety precautions can result in serious injury or property damage.

• Ensure the string trimmer engine is off and cool before beginning any work.
• Disconnect the spark plug wire to prevent accidental starting.
• Work in a well-ventilated area to avoid inhaling fuel fumes.
• Wear appropriate personal protective equipment (PPE), including safety glasses and gloves.
• Handle fuel with extreme care. Fuel is highly flammable.
• Keep fire extinguishers or other fire suppression equipment readily available.
• Dispose of old fuel and parts responsibly according to local regulations.

3. Package Contents

Upon opening the package, verify that all components are present and undamaged.

• 1 x C1M-S207 Carburetor

Note: Gaskets are typically not included with this carburetor and may need to be purchased separately or reused from the original carburetor if in good condition.

4. Product Overview

Familiarize yourself with the key components and features of the C1M-S207 Carburetor.

Figure 4.1: Carburetor Side View. This image displays the main body of the carburetor, including the clear primer bulb at the top, which is used to draw fuel into the carburetor before starting. Various fuel line connections and adjustment screws are visible on the side.

Figure 4.2: Carburetor Throttle Side. This view highlights the throttle linkage mechanism, which connects to the trimmer's throttle cable, and the red choke lever, used to restrict airflow for cold starts.

Figure 4.3: Carburetor Front View. This perspective shows the air intake opening where air enters the carburetor, as well as the two mounting holes used to secure the carburetor to the engine's intake manifold.

Figure 4.4: Carburetor Top View. From this angle, the fuel inlet port and the connection point for the primer bulb's return line are clearly visible. The screws securing the primer bulb assembly are also shown.

Figure 4.5: Carburetor Bottom View. This view reveals the underside of the carburetor, including the fuel bowl area and potentially the idle speed adjustment screw and mixture screws (if present and accessible from this side).

Figure 4.6: Carburetor Rear View. This image provides a view of the carburetor from the side opposite the throttle linkage, showing additional fuel line connections and structural elements.

5. Installation (Setup)

Follow these steps carefully to replace the carburetor on your Stihl string trimmer.

1. Preparation: Ensure the trimmer is off, cool, and the spark plug wire is disconnected. Place the trimmer on a stable, flat surface.
2. Drain Fuel: If necessary, drain any remaining fuel from the fuel tank into an approved container.
3. Remove Air Filter Assembly: Locate and remove the air filter cover and air filter. This will expose the carburetor.
4. Disconnect Fuel Lines: Carefully note the routing of the fuel lines (inlet and return) to the carburetor. Use pliers or a small screwdriver to gently disconnect them. Be prepared for minor fuel spills.
5. Disconnect Throttle Linkage: Detach the throttle cable or linkage from the carburetor's throttle arm. Take a photo if unsure of reassembly.
6. Remove Mounting Bolts: Unscrew the bolts that secure the carburetor to the engine's intake manifold. These bolts often pass through the carburetor and into the engine block.
7. Remove Old Carburetor: Carefully pull the old carburetor away from the engine. Remove any old gaskets.
8. Install New Gaskets (if applicable): If new gaskets are available, install them in the correct order and orientation between the engine, carburetor, and air filter housing. If reusing old gaskets, ensure they are not torn or damaged.
9. Install New Carburetor: Position the new C1M-S207 carburetor onto the mounting studs. Ensure it sits flush.
10. Reconnect Throttle Linkage: Reattach the throttle cable/linkage to the new carburetor's throttle arm. Verify smooth operation.
11. Reconnect Fuel Lines: Connect the fuel lines to the correct ports on the new carburetor. Refer to your notes or photos taken during disassembly. Ensure connections are secure.
12. Secure Mounting Bolts: Reinstall and tighten the carburetor mounting bolts. Do not overtighten, as this can damage the carburetor or manifold.
13. Reinstall Air Filter Assembly: Replace the air filter and air filter cover.
14. Refill Fuel: Add fresh, properly mixed fuel (if applicable for 2-stroke engines) to the fuel tank.

6. Operation

After installation, follow these steps to start and operate your trimmer.

1. Prime the Carburetor: Repeatedly press the primer bulb until fuel is visible and flowing through the clear lines, and the bulb is firm. This typically takes 5-10 presses.
2. Set Choke: Move the choke lever to the FULL CHOKE position (usually indicated by a closed butterfly valve).
3. Starting: Pull the starter cord firmly until the engine

   Ask a question about this manual

   Ask about setup, troubleshooting, compatibility, parts, safety, or missing instructions. Manuals+ will review the question and use this page’s manual context to help answer it.

   Name Email

   Question Details Submit question