What Do You Mix In A 2-Stroke Engine?

Question

1 gallon of gasoline and 1/4 gallon oil?
what is the ratio?

Answer 1

It depends on the type of engine and the type of oil...

Since this is a motorcycle related forum we'll limit it to 2 stroke bike engines.

Break it down like this;

Air cooled engines, small displacment.
Air cooled engines, large displacment.
Liquid cooled engines, small displacment.
Liquid cooled engines, large displacment.

For conversations sake we'll consider small displacment below 200cc and large over 200cc. We'll also assume, as dangerous as that is, that most riders worth thier salt will be using a high quality, name brand oil, further assuming that that oil is of semi-synthetic or pure synthetic make up.

Air cooled engines depend a good deal on the fuel charge in entering the combustion chamber for a cooling effect, operation temps on these engines also run a little higher than liquid cooled ones. So generally speaking the fuel to oil ratio will be a little oil richer. Same thing applies to the higher revving smaller displacment engines.

Liquid cooled engines will not only run cooler, but will maintain a more consistant temperature during operation, thus requiring less oil in the mixture. The same reasoning applies to slower revving larger displacment engines.

Having said that, you will find mixture ratios range from 20 parts gas to 1 part oil (20:1 or 6.4 oz of oil per 1 gallon of fuel) to 100 parts gas to 1 part oil (100:1 or 1.6 oz of oil to 1 gallon of fuel)

Most manufactures of modern two stroke liquid cooled off -road bikes suggest a 32:1 mixture, which equates out to 4 oz of oil per gallon. This suggestion has as much to do with the legal department as it does the R&D team. Not knowing how the bike is going to be riden and what type of oil the customer will be using, this rich of a mixture covers their collective butts.

To be honest, on a smaller displacment (say 85cc ~ 125cc) engine that has a rider on it that revs the snot out of it, that's probably a good place to start. In most other situations that would be a bit much.

The 'new' rule of thumb for most riders/racers these days is 40:1, or 3.2 oz per gallon. Thats a good, all around ratio, especially for larger displacment engines that don't see extended periods of high rpms.

Personally, I use a pure synthetic esther based oil that protects extremely well. Being a woods rider and riding only 250cc and open class machines I'm not running WFO a lot. My riding is short bursts of power (followed by a lot of screaming in fear on my part, but I digress) and torqueing out of turns. I've been mixing my fuel at 50:1 (2.6 oz of oil per gallon of fuel) for years with excellent results.

Using a pure mineral based oil, or a castor based oil can effect the mixture ratio as well. But there are few real motorcycle specific pure mineral oils and only a handful of the castor based ones left on the market.

Back in the day, castor based or bean oils used to be the stuff. That type of oil seeks out hot spots in metal and offered excellent protection. However, as a rule it is a dirty burning oil that leaves a gummy residue. Being as the hottest spot on a modern liquid cooled, power valved equipted engine is the variable height exhaust valve, the oil tends to gum up the power valve. That slows up it's operation, and if let go for too long can cause it to stick completely. Ask me how I know... *sigh*

Good Luck!

Answer 2

Your mixture ratio will vary depending on what engine you are running. Look in the book that came with the engine/vehicle. It is also frequently noted on the gas cap, gas tank, or other prominent location. You can buy a special measuring cup that is calibrated to show exactly how much oil creates the proper ratio mix for 1, 2, or 3 gallons. These are available just about everywhere they sell 2-stroke engines and supplies. They take all the guesswork out of it.

Answer 3

it does depend on the engine some go from 1 oil -2 gas up to 1 oil-50 gas.

it would be an idea to search for the engine to find the correct mixture ratio if you get it wrong you could damage the engine.

if you do get to much oil in the mix the engine will smoke to little and the engine will cook.

Answer 4

It could be 50/1 or 25/1. I thinck it is 25/1 but i would have to check the book

Answer 5

most motorcyles are 32 to 1, chainsaws older 32 to 1 newer like 50 to 1, all 2 stroke engines by type, weedeater, boat, etc take usally a slightly different premix.

Answer 6

<>Your mixture could be anywhere from 1:16 to 1:40, depending on the engine. You need to look it up.

Answer 7

1 gall on of gasoline and like 4-8 ounces of two stroke oil...

Check your owners manual for exact specs.

Does this help any?

Answer 8

I think 1:40

Answer 9

32:1 using the RatioRite