How to Adjust Idle On Husqvarna Chainsaw
Husqvarna chainsaw (Husqvarna) 137. Carb adjustment.
The best advice that I can give you is to consult a specialist! Believe me, for very little money, specialists will adjust the carburetor, check the general condition of the saw. But if you still need to spend carburetor adjustment on a saw Husqvarna 137 yourself, then I will try to describe this process in detail. Also at the end of the post I added a about how adjust carburetor chainsaw at idle.
Adjustment and tuning of the carburetor Husqvarna 137
Husqvarna137. Carb adjustment
In the picture above, you see three screws for adjustment. Each of them has its own purpose:
Screw T is needed to adjust idle speed.
Screw L is used to adjust low revs.
Screw H adjusts high revs.
First, screw L (turning it) we are looking for the highest idle speed. After we found them, you need to turn this screw a quarter of a turn against the clock. If in this position the circuit continues to rotate, then by rotating the screw T we achieve its stop.
Then we warm up the engine at full speed in the region of 10-15 seconds and turn the screw H a quarter counterclockwise. We wait 10 seconds and listen, the engine should work as a 4-stroke sound. If a squeal is heard, then the mixture is poor (unscrew the screw), if the enriched mixture smokes (we twist the screw).
After adjusting the low and high revs, set the idle speed with screw T. This is done as follows:
1. The engine should work
2. Turn the screw T clockwise until the chain starts to rotate.
3. Turn the screw to the other side until the chain stops.
With a properly adjusted carburetor, your chainsaw quickly picks up speed and sounds like a 4-stroke engine.
Remember that a tachometer and experience are required to properly adjust the chainsaw carburetor. Therefore, it is better to contact a specialized service!
DIY carburetor adjustment on a chainsaw
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. Basic (factory settings), carried out with the engine turned off. And final, produced on a running warm engine. 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.
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.
Chainsaw Carb Adjustment
The carburetors of most chainsaws have three adjustment screws:
- L. Jet screw for low speed adjustment
- H. Jet screw for adjusting high revs
- Screw. T at the Partner and Husqvarna (at Calm LA ). Chainsaw idle speed 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 increase accordingly; when the screws are twisted, the mixture becomes leaner. The revolutions fall.
Screw T (LA) is used to adjust idle speed. The main setting of the chainsaw is made at the factory during the final test. The carburetor, as a rule, is adjusted to supply a richer (than optimal) fuel mixture. Factory adjustment is necessary to keep the first hours of operation of the saw. Then (optionally) a more accurate carburetor adjustment is made.
We begin the adjustment by setting the idle speed, for this we turn the T (LA) screw counterclockwise, achieving a complete stop of the circuit at stable engine speeds.
For further fine adjustment, you need a tachometer and it is better to entrust it to specialists. Especially since in most cases it may not be needed.
We begin the tool setting with screw L, then use screw H and finally screw T (LA).
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 should be turned by turning it clockwise until it stops.
Screw N adjusts the power and speed. Adjusting the carburetor to lean mixture leads to excess revolutions, overheating of the engine and failure of the piston chainsaw.
We warm up the engine of the chainsaw at idle for at least 10 seconds and turn the screw N 1/4 turn counterclockwise. Let the engine run for about 10 seconds. Then check the maximum engine speed with a tachometer. If the maximum speed does not match the passport, the operation should be repeated. If the mixture is too rich, the muffler starts to smoke, when the saw is too poor, the saw squeals and overheats.
We finish the adjustment by setting the idle speed, as already described above. The idle speed is set correctly if the engine runs smoothly at minimum speed and the chain does not rotate.
A carburetor can be considered adjusted if the engine accelerates quickly and resembles a four-stroke full-throttle sound.