- Differences between gasoline engines
- How lubrication systems work
- Fuel preparation for two-stroke units
- How to refuel and maintain four-stroke motors
Any garden equipment with a gasoline engine requires careful handling and adherence to a number of operating rules. Today we will talk about the types of engines, their maintenance, namely, the correct way of refueling and the operation of the lubrication system.
Differences between gasoline engines
Gasoline engines are two-stroke and four-stroke. To understand the difference, you need to know two nuances: firstly, that a number of transient processes occur during engine operation, and secondly, that stroke means the movement of the piston from one extreme position to another, while the direction of movement does not matter. The essence of the classification of engines is that the entire cycle of transient processes in one case is repeated in two cycles, in the other – in four.
The differences between 2T and 4T, which relate directly to the refueling process, can be understood without even going into the intricacies of the work of the main units. In a two-stroke engine, the air-fuel mixture is fed into the cylinder and the exhaust gases are emitted almost simultaneously. In this case, the fuel mist initially enters the crankcase, where the crankshaft is located. When moving down, the piston squeezes part of the mixture from this chamber into the working area through a window in the cylinder wall.
In a four-stroke engine, the combustion chamber is separate from the crankcase. The air-fuel mixture is supplied through the inlet valve, the exhaust gases are released through the outlet. The valves are controlled by a separate unit driven by the crankshaft, while the order of their opening and closing is synchronized with the strokes of the piston. Due to the separation of the working area from the crankcase and the four-stroke operating procedure, complete combustion of fuel and almost complete removal of exhaust gases from the working area before the injection of the next portion of the mixture are ensured.
How lubrication systems work
Both types of motors contain a fair amount of moving parts. To increase the resource of their work, lubrication is required. Its supply in two-stroke and four-stroke engines is carried out in different ways and such nuances are directly related to the order of refueling and maintenance..
The lubricant supply in a two-stroke engine is carried out together with the air-fuel mixture. The oil dissolved in the fuel is sprayed together with the gasoline in the carburetor, the resulting mist enters the crank mechanism chamber. The configuration of the channels is organized in such a way that the path of the sprayed lubricant is as long as possible and passes through the main moving parts. At the same time, due to the special properties of the oil, most of it settles on the metal parts, and the refined fuel is transferred to the working area of the cylinder. It is thanks to these properties that oil for two-stroke engines is radically different from other types..
In a four-stroke engine, oil is permanently stored in an insulated crankcase. Its level is controlled in such a way that the crankshaft journal is periodically dipped in an oil bath. In this case, the balancing lug, when rotating, due to centrifugal force, sprays oil along the internal volume, so the lubricant gets into the piston cavity and onto the connecting rod pin, as well as onto the walls, due to which it is effectively cooled. To prevent oil from entering the combustion chamber, an additional corrugated ring is installed on the piston, which removes the remaining oil from the cylinder walls when the connecting rod moves down.
Fuel preparation for two-stroke units
To prepare fuel for a two-stroke engine, it is necessary to mix gasoline and oil in the exact ratio set by the engine manufacturer, usually a ratio of 1:50 or 1:40. The oil should be marked 2T or TC-W3, as a rule, it is colored blue. Gasoline should be used only that specified by the manufacturer in the instructions, most often it is A-92.
For cooking, you will need a plastic transparent bottle, on which the level of liquid corresponding to a volume of one liter is marked in advance. Then, using a syringe, a volume of gasoline is taken from the bottle, equal to a portion of the oil being diluted. For a mixture with a ratio of 1:50 this will be 20 ml, for a mixture of 1:40 – 25 ml. After that, add the appropriate amount of oil to the mixing container and shake the mixture thoroughly..
It is best to prepare the fuel in small portions and use it right away. Experts say that due to prolonged contact with gasoline, oil can lose its properties. You also need to remember that some two-stroke engines have separate oil injection, you do not need to prepare the mixture for them, but be sure to monitor the lubricant level in the additional tank.
How to refuel and maintain four-stroke motors
For 4T engines, gasoline does not need to be mixed with oil. However, the type of gasoline should only be used as specified by the manufacturer. This is due to the fact that with different octane number, the fuel combustion rate differs significantly, while the ignition system is set to a certain time value. The combustion temperature also differs: the materials of the piston and cylinder may simply not be designed for it..
What is really important when operating four-stroke engines is to monitor the oil level in the crankcase and update it periodically. Most engines have a dipstick in the filler plug, which marks the minimum and maximum permissible oil levels. Oil from the crankcase enters the cylinder in microscopic portions and burns there, respectively, its level in the engine gradually becomes lower. This phenomenon is absolutely normal, however, the rate of consumption should not exceed the rate set by the manufacturer..
A complete oil change must be done after a certain service life. If the instructions do not regulate this indicator, you can visually assess the quality of the oil. Darkening of the lubricant is not a reason for replacement; a certain amount of soot inevitably accumulates in the crankcase of a four-stroke engine, which is why the oil becomes black even after several hours of operation. It is necessary to monitor the transparency: turbidity or the appearance of shiny inclusions of metal shavings are the main prerequisites for washing and complete replacement.