Adjusting the carburetor of the chainsaw ensures efficient operation of the tool at full power with economical fuel consumption. Adjustment should be made with a clean fuel and air filter. For a larger number of carburetors, the adjustment is carried out by three screws: for maximum and minimum speed and idle adjustment.
Screws H and L adjust the ratio of the gasoline-air mixture determined by opening the carburetor throttle. When the screws are loosened, the mixture is enriched, and the revolutions accordingly fall; when the screws are twisted, the mixture becomes leaner. the revolutions increase.
The designation H refers to the maximum speed screw controlling the main jet, L. to the minimum speed screw controlling the idle jet. Screw S provides precise idle speed control. Sometimes, to simplify the adjustment, the number of carburetor adjusting screws available is reduced.
Setting the carburetor of the chainsaw is divided into two stages. the basic (factory settings), carried out with the engine turned off, and the final, made with the engine running warm. The exact angle of rotation should be taken from the operating instructions for the particular chainsaw. Failure to follow the manufacturer’s instructions could result in engine damage.
Video: Carburetor Stihl 180 Setting Factory Settings
Basic carb adjustment.
The adjusting screws for the maximum H and minimum L revolutions are slowly turned clockwise until they stop, after which they are turned back 2 turns, other settings are also possible
Check and adjustment of idling.
We find the highest idle speed, for this, slowly turn the screw L in different directions. After finding the position of the highest engine speed, turn screw L 1/4 turn counterclockwise. If the chain rotates at idle, screw T or (S) should be turned by turning it clockwise until it stops.
Checking and adjusting the maximum speed.
Changing the maximum number of revolutions is carried out by screw H. When it is screwed in (clockwise rotation), the revolutions increase, when inverted. are decreasing. Chainsaw engines have the highest rotation speed of 11,500 rpm. up to 15000 rpm Ignition does not provide a higher speed, in addition, it becomes dangerous for the engine. The maximum speed can be determined by interruptions in the ignition. If they come, screw H is slightly turned counterclockwise.
If the engine is not tested for acceleration and maximum speed, then the adjustment of the chainsaw cannot be considered complete.
With a smooth pull of the gas trigger, the engine must confidently and quickly gain speed from idle to maximum (from 2800 rpm to 11500-15000 rpm, depending on the unit). If the speed is slow, delayed, screw L must be slowly turned out counterclockwise, but no more than 1/8 turn.
After adjusting the acceleration and maximum revolutions, you should again check the operation of the saw at idle. the engine must run stably, the chain must not move. Chainsaw setting should be repeated if this condition is not met but with the exception of the basic adjustment step.