Electric Carburettor Heating: Always Ready for Work

A temperature-controlled electric heater prevents ice from forming inside the carburettor during cold, humid weather. Even as intake air cools rapidly when fuel atomises, the heater maintains smooth fuel-air flow — so power stays consistent and stalling is avoided.

STIHL models equipped with electric carburettor heating and heated handles carry “V-W” in the product name.

Immediately after fuel exits the carburettor nozzles it mixes with air — dropping intake air temperature by up to ~9 °C. In the 3 °C to 10 °C range, moisture can condense and freeze around the throttle valve, restricting airflow and reducing performance, potentially causing engine failure.

• < 3 °C: air humidity is typically too low for icing.
• ≥ ~10 °C: conditions are generally warm enough to avoid icing.
• Most critical: autumn, winter and early spring, especially within 3–10 °C.

1) Passive warm-air routing (domestic/occasional models)

• “Winter/Summer” slide opens to route cylinder-warmed air into the air filter.
• After a few minutes of running, carburettor temperature rises above the icing zone.
• User action required: switch slide Open for winter (e.g., with seasonal routines).

2) Electric carburettor heating (professional forestry models)

• Integrated heater element auto-activates at the critical temperature range — no user input.
• Powered by a dedicated generator near the flywheel.
• Heated handles are included with electric carb heating on STIHL pro models (“V-W”).

Both systems are most important during the first ~10 minutes of operation; afterwards engine heat typically keeps temperatures above the icing threshold.

The system comprises a heater element positioned before the carburettor and a thermostat (on the pump-side cover or on the heater). When carburettor temperature drops below approx. 10 °C, the thermostat switches the heater on; as temperature recovers, it switches off — maintaining optimal flow and idle stability.

• Standalone design: no fuel routed through the heater; no complex engine modifications.
• Low weight impact: minimal mass added to the saw.
• Auto-regulated: generator-supplied power; no user action required.

• Reliable starting and smooth running in cold, damp conditions.
• Stable idle and low-speed performance with fewer seasonal carb adjustments.
• Heated handles (V-W) add comfort and control during long winter shifts.
• Simple, robust architecture with minimal added weight.

Electric carburettor heating is included on selected STIHL chainsaws (e.g. MS 261 C-M, MS 500i) and is not a universal standard. The heater modules are tailored to those platforms and cannot be retrofitted to other models.

1. Consult your model’s manual to locate the winter/summer slide or valve.
2. Set to Open (winter) to route warmed air to the filter.
3. After several minutes of operation, the carburettor will typically be out of the icing zone.
4. Return to summer setting as ambient temperatures rise.

• Electric carburettor heating prevents ice formation and maintains performance in 3–10 °C, humid conditions.
• Professional STIHL models add heated handles; look for “V-W” in the name.
• System is standalone, lightweight, and auto-regulated — no complex engine changes.
• Not retrofit-compatible; consult a dealer for model guidance.