The mixture quality is adjusted in the carburetor. To do this, turn the screw for the amount of the mixture. The main task is to achieve the supply of a mixture of air and fuel in approximately a proportion of 14 parts of air to 1 part of fuel. It is better to do this at a special stand, but you can achieve a good result on your own.
It is necessary
Compressometer, set of tools
Instructions
Step 1
Check the serviceability of the engine, make sure that the compression in all cylinders is the same using a compressor. If its readings in different cylinders are very different, repair the engine, adjusting the quality of the mixture will not improve its performance. Start the engine and let it reach operating temperature. Reduce idle speed with a special screw to a minimum, when there is a subjective feeling that if you turn the screw a little more and the motor will stall, although it still runs smoothly. Stop the engine and tighten the screw for the amount of the mixture until it stops.
Step 2
Twist the fuel needle half a turn and then back it off one turn. If, during twisting, the revolutions decreased, and during subsequent unscrewing, they increased, the mixture is too lean, if, on the contrary, it is too rich. In this case, turn the screw for the amount of the mixture to where the speed increases. If, at the same time, the screw needs to be tightened, and the revolutions increase until it is fully tightened, you need to choose a jet with smaller holes. If the RPM rises when unscrewing the screw, then install a jet with large holes. If, when manipulating the needle, the motor does not change, this setting is not required.
Step 3
Now, by turning the screw, find the maximum rpm, at which its rotation in either direction causes only a drop in engine rpm. When they decrease when tightening the screw, the mixture becomes leaner. This can save fuel, but the engine can overheat as the mixture ignites at high temperatures. A decrease in speed when unscrewing the screw signals that the mixture is too saturated. This can lead to excessive fuel consumption, but the engine will not overheat, since the rich mixture ignites at lower temperatures. The difference in combustion temperatures of the mixture can reach 500 degrees Celsius, so you need to be very careful when manipulating the quality of the mixture.
