How to Replace a STIHL Chainsaw Carburetor

📅 Updated: 2026-07-29  ·  ⏱ 20 min read  ·  🔧 Difficulty: Intermediate

When your STIHL MS170 or MS180 starts hard, runs lean, or floods easily, the carburetor is usually the culprit. In this guide we'll show you how to swap it in about 20 minutes using basic hand tools — no workshop needed.

🛠 Tools You'll Need

• 8 mm & 10 mm socket wrench
• Phillips screwdriver
• Flathead screwdriver (for impulse line clamp)
• Clean rag / brake cleaner
• New carburetor + gasket set (included with TATU carburetor)

⚠️ Safety First

• Kill switch OFF, remove spark plug boot
• Work in a well-ventilated area — no open flames
• Don't reuse old fuel lines if they are cracked or brittle
• Allow engine to cool completely before starting

🔧 Step-by-Step Replacement

Step 1 – Remove the Air Filter Cover

Unscrew the top cover knob (tool-less on most STIHL models). Lift off the cover and remove the foam air filter. Set aside in a clean place.

📸 Insert image: stihl-ms170-air-filter-removed.jpg | Alt: STIHL MS170 air filter removed showing carburetor

Step 2 – Disconnect Throttle & Choke Linkage

Carefully pop off the plastic ball joints connecting the throttle rod and choke rod to the carburetor lever. Use a small flathead if needed — don't pull on the plastic rods themselves.

📸 Insert image: stihl-ms170-throttle-linkage.jpg | Alt: Throttle and choke linkage disconnected from STIHL MS170 carburetor

Step 3 – Unclip Fuel Inlet & Impulse Line

Using pliers or your fingers, squeeze the spring clip on the fuel inlet hose and slide it off the brass barb. Repeat for the smaller impulse line. Expect a few drops of fuel — keep your rag handy.

Step 4 – Unscrew the Two Mounting Nuts

Use an 8 mm socket to remove the two nuts securing the carburetor to the intake manifold. Gently wiggle the old carburetor free. Note the orientation of the gaskets for reassembly.

📸 Insert image: stihl-ms170-old-carburetor-removed.jpg | Alt: Old carburetor removed from STIHL MS170 with mounting nuts

Step 5 – Fit the New TATU Carburetor + Gasket

Place the new gasket onto the intake studs (matching the orientation of the old one). Slide the TATU replacement carburetor onto the studs. Hand-tighten the two nuts with the 8 mm socket — do not overtighten.

Reconnect the fuel inlet hose and impulse line. Push until you feel them seat over the barbs, then secure with the spring clips.

📸 Insert image: tatu-carburetor-installed-stihl-ms170.jpg | Alt: TATU replacement carburetor installed on STIHL MS170 chainsaw

Step 6 – Reconnect Linkage & Baseline Adjustment

Snap the throttle and choke linkage ball joints back onto the carburetor levers. Before reassembling the air filter, set the 'L' and 'H' adjustment screws to 1.25 turns out from lightly seated (baseline setting).

Reinstall the air filter and cover.

🚀 Startup & Fine-Tuning

Start at half choke, warm up for 2 minutes, then fine-tune with a tachometer if available. If you're unsure about H/L tuning, read our Chainsaw Carburetor Tuning Basics guide.

Disclaimer: This guide is for informational purposes only. Always consult your equipment's service manual before performing repairs. TATU Technologies Ltd. is not liable for damage or injury resulting from improper installation.