Quck answer
To adjust the needles on a McCulloch chainsaw, follow these steps:
1. Locate the high and low speed adjustment screws on the carburetor. They are usually marked with an “H” and an “L” respectively.
2. Start the chainsaw and let it warm up for a few minutes.
3. Turn the low speed adjustment screw (L) clockwise until it stops, then turn it counterclockwise 1 and a half turns.
4. With the chainsaw running at full throttle, turn the high-speed adjustment screw (H) clockwise until the engine starts to slow down. Then, turn it counterclockwise until the engine runs smoothly and reaches maximum RPM.
5. Fine-tune the low-speed adjustment screw (L) by turning it clockwise or counterclockwise until the chainsaw idles smoothly without stalling.
6. Test the chainsaw’s performance by cutting a small piece of wood. If necessary, make further adjustments to the screws until the chainsaw runs smoothly and efficiently.
The carburetor of a McCulloch gas chainsaw contains needles that control the gas inflow during various engine speeds. The needles can be adjusted using screws located on the outside of the carburetor. Making these adjustments can solve many engine problems and enhance the engine’s overall performance. However, improper adjustment may cause damage to the carburetor and engine. Therefore, it is recommended that a professional makes these adjustments. Before making any adjustments, ensure that it will not void your warranty.
Step 1
Using a screwdriver, loosen and remove the screws on the top cover. Lift off the cover, along with the cylinder and air filter. Take out the air filter box beside the cylinder and remove the filter from the box.
Step 2
With a brush, clean the filter, box, cylinder fins, and the area surrounding them. Remove all dust and dirt. Leave the filter and box out to access the carburetor.
Step 3
Open the fuel tank and dispose of any old or bad fuel according to environmental regulations. Fill the chainsaw with freshly mixed McCulloch chainsaw gas. Start the engine and let it warm up for several minutes. Locate the adjusting screws on the side of the carburetor.
Step 4
Identify the idle speed adjusting screw on the carburetor. Slowly turn the screw clockwise with a small screwdriver until the clutch engages and the chain starts to spin. Ensure that the moving bar will not hit anyone or anything when it starts to spin.
Step 5
Immediately stop turning the screw as soon as the chain starts rotating. Turn the idle screw counterclockwise until the chain stops spinning. Slowly turn the screw clockwise to find the highest idle speed before the chain starts moving.
Step 6
Identify the low speed adjusting screw on the carburetor. Slowly turn the screw clockwise with a small screwdriver until you hear the engine producing surging noises. Stop turning and rotate it counterclockwise until the engine produces bubbling noises.
Step 7
Rotate the low speed screw between these two settings to find the optimal low speed. Press the trigger and ensure that the acceleration is sharp and clean. Adjust the screw slowly as needed. Do not go beyond the surging or bubbling noises. Once the low speed is set, readjust the idle speed screw as before.