The carburetors of most chainsaws have three screws to adjust:
- L. nozzle screw for adjusting the low speed
- H. nozzle screw to adjust high revs
- Screw. T at Partner and Husqvarna (at Calm LA). adjustment of idling of the chainsaw
The screws H and L regulate the ratio of the mixture of gasoline and air determined by the opening of the throttle valve of the carburetor. When the screws are unscrewed, the mixture is enriched, and the turnovers increase accordingly, when the screw is turned, the mixture is depleted. the turnovers fall.
Screw T (LA) is designed to adjust the idle speed. The main “setting” of the chainsaw is made at the factory during the final test. The carburetor is typically adjusted to supply a richer (than optimal) fuel mixture. The factory adjustment is necessary to maintain the first hours of the saw. Then (optionally) a more precise carburetor adjustment is made.
- We start the adjustment by setting the idle speed; to do this, rotate the screw T (LA) counterclockwise, ensuring that the circuit stops entirely at steady engine speed. For further fine adjustment, you need a tachometer, and it is better to entrust it to specialists. over, in most cases, it may not be necessary.
- We start the tool set with screw L, then use screw H and at the end screw T (LA). We are looking for the highest idle speed, for this, we slowly turn the screw L in different directions. After finding the position of the highest revolutions of the engine, you must turn the screw L 1/4 of a turn counterclockwise. If the chain rotates at idle, the screw T should be turned by simply turning clockwise until it stops.
- Screw H regulates the power and frequency of turns. Adjusting the carburetor to a lean mixture leads to excessive speed, overheating of the engine, and failure of the piston chainsaw.
- We warm up the chainsaw engine at idle for at least 10 seconds and turn screw H 1/4 turn counterclockwise. We allow the engine to work for about 10 seconds, then check the maximum engine speed with a tachometer. In case of discrepancy between the maximum revolutions of the passport, the operation should be repeated. When feeding too rich a mixture, the silencer starts to smoke, when too weak, the saw squeals and overheats.
- We finish the adjustment by setting the idle speed, as already described above. Idling speed is set correctly if the engine runs without failures at minimum speed and the circuit does not rotate.