Operating any two-stroke internal combustion engine requires the owner to pay special attention to the preparation of the fuel mixture. Unlike four-stroke analogues, where the oil is in a separate crankcase, here the lubricating liquid must burn with the gasoline, providing protection for rubbing parts. Incorrect preparation of the emulsion is the fastest way to disable the engine, often without the possibility of recovery.
The mixing process seems trivial, but it is at this stage that the most fatal errors are made, leading to piston bullies or, conversely, to the exhaust system coking. Accuracy of dosing The components are critical to the life of the unit, and in this article we will look at all the nuances, from the choice of materials to the final shake.
Principle of operation and the need for mixing
The two-stroke engine doesn't have a full-blown lubrication system in the classical sense, because the crank-shaft mechanism is washed by a fuel-air mixture. The oil added to the gasoline creates a thin protective film on the surfaces of the parts that prevents dry friction at high revs. lubricantThe engine will jam in minutes due to overheating and friction of the metal against the metal.
On the other hand, the excess oil in the mixture causes it to not burn completely, and this causes the formation of soot on the spark plug, piston rings and in the muffler. Octane number But it's the balance of lubrication and fuel that determines the durability of the engine. Modern synthetic oils allow the engine to work cleaner, but the proportions cannot be broken.
It's important to understand that the emugation process is not instantaneous. Molecules need time and energy (in the form of shaking) to distribute evenly. Simply pouring oil into a full tank of a outboard motor or chainsaw without first mixing it in a separate container is a guarantee of uneven lubrication.
⚠️ Warning: Never try to mix components directly in the engine tank by adding oil to top of the gasoline, which will lead to the engine running on pure gasoline (risk of bullying) first, and then on pure oil (coxing).
Selection of components: gasoline and oil
The basis of the mixture is gasoline. For most modern technology, whether it's outboard motors. Tohatsu, Yamaha garden-house Stihl, HusqvarnaIt is recommended to use fuel with an octane number of at least 92 (AI-92). The use of AI-95 or AI-98 gasoline often does not make sense, since they contain additives that may not have time to burn in simple two-strokes, forming a soda.
The second component is a special oil for two-stroke engines. 2T or two-strokeThe normal motor oil for cars (4T) is categorically not suitable, since it is not designed to burn with fuel and instantly disable the candle and silencer, divided into mineral, semi-synthetic and synthetic oils.
- 🛢️ Mineral oils are suitable for older engines and low-revving machinery, but require more frequent replacement of the mixture.
- 💧 Semi-synthetics is the best choice for most medium-power outboard motors and household-class chainsaws.
- 🧪 Synthetics – mandatory for high-speed engines, sports snowmobiles and water-cooled equipment.
The shelf life of the finished mixture is limited. Gasoline is oxidized, and the oil precipitates or loses its properties. Prepare a mixture It should be in small volumes, designed for 1-2 weeks of active use, and it is not recommended to store the mixture in plastic canisters for more than a month.
Table of proportions and calculation of mixture
The most important factor is the ratio of oil to gasoline volume, depending on the type of engine and manufacturer's recommendations. Old Soviet engines could require a ratio of 1:25, while modern Japanese and European units operate at 1:50, using measuring tanks or syringes allows you to achieve high accuracy.
Below is a table that helps you quickly calculate the amount of oil needed for different volumes of gasoline. Always round the amount of oil upwards if you are on the verge of values, it is better to slight the excess of lubrication than lack of it.
| Proportion (Penzines:Oil) | Oil per 1 litre of gasoline (ml) | Oil per 5 liters of gasoline (ml) | Oil per 10 liters of gasoline (ml) |
|---|---|---|---|
| 1 : 25 | 40ml | 200 ml | 400ml |
| 1 : 33 | 30.3 ml | 151.5 ml | 303 ml |
| 1 : 40 | 25ml | 125 ml | 250 ml |
| 1 : 50 | 20ml | 100ml | 200 ml |
For accurate measurement of small volumes of oil, it is convenient to use a medical syringe of 20 or 50 cubes or special measuring vials, which often come with oil. An error of 5-10 ml per liter of gasoline can drastically change the lubricating properties of the mixture. Always read the instructions for a particular motor model carefully, as the requirements may vary.
Step-by-step instructions: how to properly interfere
The cooking process requires clean containers and a sequence of actions. You can't just pour everything into a tank. Use a clean gasoline canister or a special mixing tank that doesn't react with hydrocarbons. Metal or plastic containers should be dry and water-free.
☑️ Checklist for preparation for mixing
First, about half the amount of gasoline you need is poured into the tank, then you add the calculated amount of oil, and then you have to shake the tank a few times, and you have to break the oil into the gasoline, and then you add the rest of the gasoline, and then you mix it thoroughly again.
This sequence (oil to part gasoline -> mixing -> adding the rest of gasoline) provides the most uniform structure of the emulsion. If you pour oil on the bottom of an empty canister and then pour the gasoline, it will be more difficult to mix it. The finished mixture should be used for a month.
⚠️ Warning: Do not store the finished mixture in transparent containers in the light. Ultraviolet and temperature changes accelerate the oxidation of gasoline, which leads to the formation of resins that clog the carburetor.
Use a mesh filter funnel when pouring the mixture into the tank of machinery, this will delay possible debris or fibers from the canister, protecting the fuel system.
Frequent errors and their consequences
One of the most common mistakes is to use old, lying gasoline, which loses its properties after 2-3 weeks of storage, especially in the off-season. carburetor It is overgrown with a lacquer coating, which is extremely difficult to remove without a complete disassembly.
The second mistake is the confusion of the units. Beginners often confuse milliliters with grams or liters, which leads to a tenfold error in concentration. Always check the dimension on the measuring capacity. It is also dangerous to mix oils of different manufacturers and types (mineral with synthetics), since their additive packages can enter into a chemical reaction.
- ❌ Use of spent oil - guaranteed output of the piston group in one motor hour.
- ❌ Mixing "by eye" without measuring dishes is a lottery with a high risk of major repairs.
- ❌ Storing the mixture in the tank of equipment for the winter - gasoline will evaporate, leaving oil and resins that will sour the rings.
Some users try to save money by buying cheap mineral oils for high-powered engines, which leads to overheating, since mineral water has the worst lubrication rates at high temperatures and loads. The price of error In the form of a replacement of the piston group always exceeds the cost of quality oil.
What happens if you transfuse oil 2 times more than normal?
The engine won't explode, but you'll get thick black smoke from the silencer, a lot of soot on the candle and a loss of power. The candle will roll in a few minutes. You'll have to clean the exhaust system and change the candle. It's not fatal, but it's unpleasant.
Engine break-in and operating modes
A new engine or engine after major repairs requires breaking in, during which time the rubbing parts are rubbed together, and lubrication requirements are maximum. Often manufacturers recommend for the break-in period (the first 5-10 hours) to make the mixture slightly richer in oil, for example, 1:40 instead of the regular 1:50.
The running mode should be gentle, you should not give full gas or, conversely, keep low speeds for a long time, you need to change the load so that the piston rings work evenly. Temperature conditions Also important: do not overheat, but do not let the engine cool completely between starts.
After the break-in, you can switch to the standard proportions specified in the manual. If you use the technique seasonally (for example, an outboard motor), then at the end of the season, be sure to develop the residue of the mixture from the tank or drain them. Leave the mixture in the carburetor for the winter is a sure way to get problems with starting in the spring.
The quality of the prepared mixture directly affects the engine life: saving on oil or violation of proportions costs 10-20 times more than the cost of the oil itself during repair.
Can I mix oil and gas a month before fishing?
It is recommended to store the finished mixture for no more than 30 days in a tightly closed metal canister in a cool place. After a month, the gasoline begins to oxidize, losing its octane number, and the oil may begin to delaminate. For critical trips, it is better to prepare a fresh mixture.
Which petrol is better: 92nd or 95th for two-stroke?
For most two-stroke air and water-cooled engines, the optimal is the AI-92 gasoline. It burns more slowly and smoothly, heats the cylinder less. The 95th gasoline often contains additives that do not burn completely in simple engines, forming a coar on the piston and silencer.
Why does the engine stop after winter?
Most likely, the carburetor left the remnants of the old mixture, the gasoline evaporated, leaving a thick oily substance that clogged the jellyplates, requiring purge or disassembly and cleaning of the carburetor, as well as replacement of the fuel filter.
Can I use car oil for a two-stroke engine?
Absolutely not. Car oil (for four-stroke engines) does not burn completely, but should circulate in the system. In a two-stroke, it instantly cokes the candle, piston rings and exhaust system, leading to loss of compression and jamming.