Just started dirt bike riding, and not sure which premix ratio to use, how to calculate how much oil you need, the best oils, or how to mix fuel?
No problem! This 5-minute guide to 2 stroke premix ratios has everything you need to know.
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Popular Premix Ratios
You’ll find that seasoned motocross riders stick to one of four premix ratios on their dirt bike. I personally have always used 40:1.
Below is a chart that shows the fuel to oil ratio, and the amount of oil needed when mixing gas for 2 strokes. Some calculations are specific, but honestly, if you put a few ml more/less than you should, meaning the mix changes from something like 40:1 to either 39:1 or 41:1, it’s not going to make any difference.
Premix Ratio Chart (Per 5L of Fuel)
| Fuel Ratio | Premix Oil Needed (per 5l) |
|---|---|
| 25:1 | 200ml |
| 32:1 | 156.25ml |
| 40:1 | 125ml |
| 50:1 | 100ml |
Premix Ratio Chart (Per 1 U.S Gallon)
A US gallon is 3.785.412 liters. So, don’t be using the calculations above if you’re using a gallon fuel can.
Instead, use the ones below:
| Fuel Ratio | Premix Oil Needed (per US Gallon) |
|---|---|
| 25:1 | 151.41ml |
| 32:1 | 118.30ml |
| 40:1 | 94.64ml |
| 50:1 | 75.71ml |
How To Premix 2 Stroke Gas For Dirt Bikes
What You’ll Need
-
Oil
One thing that affects how much oil you’ll need, is the quality of the oil. ALWAYS stick to high quality brands. If not, there’s a good chance you’ll be forking out much more on engine repair bills than you should be. 
A quality premix from any leading brand will be fine, such as the ones we listed in our guide to the best dirt bike oils. A good example would be Motul 800, but there are plenty of other brands to choose from, such as:
- Amsoil
- Bel-Ray
- Castrol
- Lucas Oil
- Maxima
- Motorex
- Motul
- Putoline
- Silkolene
-
A Measuring Jug
Any old measuring jug will do. Just make sure it’s wiped clean, and I’d suggest NOT using the one you use to whisk up an omelette mix ?. 
I use separate measuring jugs for all fluids (coolant, gearbox oil, premix and so on). They’re not that expensive. You can grab a few online for a couple of dollars.
Some even have a premix calculator on the side, like this one.
-
A Fuel Can
I have a large container that’s a few gallons – used for 3-hour offroad races, as it’s easier to fill the bike quickly on my own.
If I’m just going for a practice day at a local track, I just mix up a few 5L cans.
It’s up to you which route you take. As with the oils, if you use fuel for other things (petrol, diesel, or premixed using different oil), keep your dirt bike cans separate.
How To Premix Dirt Bike Fuel
- Measure out the premix oil you need in your (clean!) measuring jug
- Pour it into your fuel can and give it a quick shake
- Pour a little fuel into the measuring jug and mix any oil that’s stuck to the jug, and pour it back into the fuel can
- Close the can and give it a shake for a minute or two (you might have to open the lid to let air escape if it doesn’t have a vent).
Final Notes
Naturally, premix will settle to the bottom of cans AND your fuel tank.
If you still have fuel left in your tank when you go riding next, make sure you give the bike a good shake around.
The same goes for your fuel can, if you have spare premixed fuel in a can for your next ride, you need to shake it/mix it before pouring it in your bike, as you would if you’d only just poured in the oil.
If you don’t, your bike will either be swallowing too much oil, or it will be running on a mix that’s lean on oil, and that’s going to cause engine problems.
