Motorcycle fuel: stabilizer or empty tank before winter?

The real problem: fuel degrades

Modern petrol contains ethanol, which absorbs moisture and degrades in 1–3 months. Result on a mothballed motorcycle: gums and varnish that clog carburettor jets or foul injectors, plus corrosion from condensation.

Full tank + stabiliser: the right answer

The "empty vs full tank" debate is settled in favour of full tank + stabiliser:

The procedure 1. Fill the tank completely (reduces air, so condensation). 2. Add stabiliser at the correct dose (read the product instructions). 3. Run the engine for 5–10 minutes: this is crucial—it circulates the treated fuel through to the carburettor/injectors and around the whole circuit. 4. Switch off and store.

Carburettor case On a carburetted motorcycle, some people also empty the carburettor bowl (drain screw) after circulating the stabiliser through the circuit. This prevents any deposits in the bowl. On fuel injection, this isn't necessary.

Come spring The stabilised fuel is ready to go. Reconnect the battery, check fluid levels, and start up. For the complete winterisation checklist, see our motorcycle winterisation guide.

Have a question about storing your specific motorcycle? Ask the mechanic AI.