Answer
Sep 15, 2025 - 06:19 PM
Yep, the Stihl MS 311 and MS 391 have a summer/winter shutter that needs to be set correctly — and if it’s not, cold starts can be a pain.
Here’s how to switch it:
- Find the shutter — It's right behind the air filter cover, near the cylinder's cooling fins.
- To set for winter use — Flip the shutter open so warm air from the engine gets pulled into the carburetor. This helps prevent carb icing and makes cold starts easier.
- To set for summer use — Flip the shutter closed so the carb pulls in cool air.
Stihl even marks this with a little snowflake and sun icon — just match the tab to the right side.
If the shutter's stuck in summer mode during cold weather, yeah, that could definitely be the reason it’s tough to start. Once it's flipped over to winter mode, it should fire up easier 👍🏻
