Mixing 2-Stroke Gas Made Easy

Today we walk you through mixing gas for your two-stroke. We also talk about different levels of octane you can use for your bike and how much fuel to mix up at one time.

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Jay Clark/Dirt Bike TV has been around the Dirt Bike industry for thirty years and is always looking to learn and help others do so as well. Give a follow or drop an email if you have any questions or comments. Thanks for watching!
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[rider]

I find that increasing the BTUs per pound is better than actually using higher octane gas. I started experimenting in 1992. Using regular pump gas in my race bikes. A mix ratio of about 12% to 15% percent of aromatics; toluene or xylene with a slight bit of methanol or denatured alcohol for stability. Basically I was mixing approximately a half gallon to 4 gallons of gas. The fuel mixture is denser, which burns hotter, creating more BTUs which results in more power and less pre detonation.

[tikka]

Another great video from Jay! The formula for mixing gas to get an octane number is:
( [ % Fuel A ] x [ Octane of Fuel A ] ) + ( [ % Fuel B ] x [ Octane of Fuel B ] ) = Octane of Mixture
Here’s an example. Let’s say you mix 3 gallons of 110 with 2 gallons of 100 and you want to know the octane of the resulting 5 gallon mixture.

The percentage of 110 in the mix is 3/5 = 0.60 (60%).

The percentage of the 100 octane fuel in the mix is 2/5 = 0.40 ( 40%).

Plugging the information into the equation:

(0.60 x 110) + (0.40 x 100) = 66 + 40 = 106
A good number I like to shoot for is 93 octane. It’s important if available to use ethanol free gas as ethanol has less energy per volume. 89 ethanol free mixed with a 110 leaded fuel like Sunoco standard or C12 is a good every day riding mixture. Works in the 125 RM and a high compression 250f. More isn’t always better.
In addition to increasing octane the selected C12 “race” gas has a specific gravity. That plays a role in jetting for carbureted bikes. It effects how the fuel gets picked up through the jets. Specific gravity also plays a role in burn rate. 2 strokes can benefit from a lower specific gravity number for high burn rate and complete combustion. There are different additives to get octane. Additives such as lead or MMT contribute to increasing octane as well as higher refinement of base petroleum. This is my limited knowledge on fuels and just my 2 pennies. Oxygenated fuels are another topic altogether.

[no-namecrown]

In Australia we have 98 octane from Shell service stations. That's the only fuel I'll use.

[jetdr]

Depends on how hard you ride as well, if you are a track star on the pipe, you can run a high flash point pre mix like R50. if you do more trail riding, I would run a Maxima K2 or AMSOIL Dominator which has a much lower flash point. When I run track I use Klotx 110 with Castor 927, when I run single track I run half non ethanol pump and 110 mixed with K2. I have an 09 yz250 with almost zero internal engine wear.

[mikebrown]

Makes me excited that VP is working on something new for the two strokes 👌🏼. Love these segments Clark. 👍🏼

[diyjeff]

I have those gas tanks. They make some cheap tube benders that keep the clear tube bent making filling your bike, or anything for that matter, much easier!!

[noControl]

I just bought a gallon sized jug that is marked and mix my gas 1 gal at a time vs. trusting the marking on the fuel jug, plus I'm always adding fuel to a jug that already has fuel in it. A lot easier than having to break out the calculator and guestimate on the decimal portion. Measure the gas, measure the oil in the ratio rite, then pour gas in the raio rite and pour back into the gas measure jug, then dump the whole thing in the gas can. Every bike gets is own can, and the only gas that gets put into the 2 stroke's can is pre-mixed so no chance of forgetting to add the oil.

[bradmiller]

I run 2- 5 gallon metal gas cans. At home I dump a half gallon of klotz hitrate octane booster in each. Next i put in my Amsoil dominator at 44:1. I then drive to the store and put in 4.5 gallons of 91 non-ethanol, "premium rec. gas" here in MN. I use the pump to tell me I put in the right amount of gas in each can. Now I have decent quality 100 octane at a fair price to go in my stock 21' yz250x. In the metal cans it lasts longer. I always out of habit shake the can before I pour gas in my bike. If I had a higher performance bike or motor I would probably run vp.

[AdventureAndy]

Other points to add are the flash point of the oil for lower engine temp trail riding and certain natural oils like Castor 927 will separate with AvGas.

[mx]

I ran the recommended 30:1 on my 2022 YZ250 and fouled a lot of plugs. I think I will be mixing 40:1 from now on, thanks! 30:1 would probably be good if I was racing my bike on a track running the engine hard.

[human]

In a 2022 KTM 300 XC I run 91 Octane Ethanol free.
I recently verified the factory measurements on red plastic gas cans and found the labelling to be way off by more than 1 litre, 1 U.S. quart and more.
I used 2 different measuring cups and a specific volume from 1 gas pump at a gas station. All 3 matched but noi gas can matched so I used a majic marker to mark the red gas cans I have.
I keep the various volumes of gas : oil ratios on my phone for quick access. Or use a free premix app.

[yzrippin]

Pro tip a 12 oz gatorade bottle filled to the brim gives you a perfect 50 to 1 into 5 gallons of gas it's been 25 years I own a landscaping business I've never blown anything up

[Natedoc]

2 stroke oil is an excellent fuel stabilizer and won’t hurt 4t engines when mixed quite lean, particularly in small carbureted machines like lawn mowers etc

[Greg-oick]

Best i can get locally is 91 from the pump. Got an apex head done for just that on my 250

[billsynder]

The best way to mix 2 stroke fuel is to have a common mix for all your bikes . A pint of oil to 4 gallons of gas gives you 32 to 1 which works well for all bikes. If I am mixing bean oil for alchohol motors I mix two pints to five gallons for 20to one . If you have a lot of bikes or if you do long race weekends, the just having a can for the weekend works better than mixing two cans at a time. Also steel cans are much better for gas than plastic. I would only use plastic for alchohll.

[stevenlocke]

For 30 some years I have went with 128 oz to a gallon so divide 128 and your ratio 128 divide 32 equals 4 so 4 oz to every gallon 128 divide by 40 equals 3.2 oz to a gallon etc.etc

[jpesicka]

Use T2. Best switch I've ever made. Instant 2 HP upgrade. No more mixing.

[ht]

Good idea to change your float to copper or brass, puts tiny holes 🕳️ n plastic float

[westadam]

Pick your favorite oil pick your desired ratio use the highest octane fuel you can get out of the pump, jet your bike to that specific ratio and you'll have no problems.

[bigshnitzeljesse]

Clear/white cans show premixed oil color. My 2 stroke oils have plenty of coloring