Start with the manual
The owner’s manual or a sticker near the filler cap tells you the minimum octane rating and the fuel type your engine needs. Using a lower octane than required can cause knocking and damage. A higher octane than required usually brings no benefit.
What the numbers mean
- Octane rating shows how well fuel resists knocking. Different countries use different scales, such as RON or AKI, so the number on the pump may not match the manual directly.
- Check which scale your manual uses and choose the equivalent grade.
Ethanol blends
- Many fuels contain some ethanol. Most modern bikes are designed for the blends sold in their market, but older bikes and some fuel systems are sensitive to higher blends.
- Ethanol attracts water, so a bike that sits for weeks can suffer from stale or contaminated fuel.
- The manual states which blends are approved. Do not use a blend it does not allow.
Stale fuel and storage
- Fuel can go off in a few months, especially in a half-empty tank. If the bike will sit for a long time, follow the storage advice in the long-term storage guide.
- If a bike has been left a long time and starts badly, do not mix in lots of fresh fuel and ride off. Ask a mechanic if you are unsure.
If you put in the wrong fuel
If you have filled with a fuel your bike is not designed for, do not start the engine. Ask for help and have the tank drained. Starting it can spread the problem through the system.
Fuel grades and blends differ by country and change over time. Always follow your owner’s manual.