Use this calculator to work out how much two-stroke oil to add to your fuel for common premix ratios.
It is useful for vintage motocross, enduro and trail bikes including Yamaha YZ, Honda CR, Suzuki RM, Kawasaki KX, Maico, Husqvarna, KTM and other classic two-stroke motorcycles.
| Ratio | Typical Use |
|---|---|
| 20:1 | Early vintage two-stroke engines and some older manufacturer recommendations |
| 25:1 | Older air-cooled motocross and enduro bikes |
| 32:1 | Common vintage motocross premix ratio |
| 40:1 | Often used with modern quality two-stroke oils |
| 50:1 | Some later two-stroke engines and modern oil recommendations |
| Fuel | 25:1 | 32:1 | 40:1 | 50:1 |
|---|---|---|---|---|
| 5 Litres | 200 ml | 156 ml | 125 ml | 100 ml |
| 10 Litres | 400 ml | 313 ml | 250 ml | 200 ml |
| 20 Litres | 800 ml | 625 ml | 500 ml | 400 ml |
Two-stroke premix ratios describe how much fuel is mixed with one part of oil. For example, 32:1 means 32 parts fuel to 1 part oil.
Vintage motocross and enduro bikes often use richer oil mixtures than modern motorcycles. Always check your workshop manual, oil bottle recommendations and engine condition before choosing a ratio.
Browse the VMXOwners.au archive for vintage motocross bike specifications, workshop data, tyre sizes, carburettor settings and model information.
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