When it comes out of the factory, the blower is set to the ideal carburetor settings which provide optimum fuel to air mixture under most operating conditions.
But with time and use, the carburetor setting could go awry. This could mess up the fuel-to-air ratio inside the engine resulting in either a lean or rich fuel mix.
Thankfully, you can adjust the settings easily using screws that are easily visible on the left side of the machine next to the air filter.
Adjustment Screws
There are three adjustment screws that allow you to control the fuel mixture.
- H screw – Controls the mixture when the blower is at full throttle.
- L screw – Controls the mixture when the blower is at low throttle
- LA screw – Controls the mixture when the blower is idle.
How To Adjust 56 Stihl Blower Carburetor
Preparation
You are going to need a flathead screwdriver, a pair of pliers, and a carburetor screw adjustment tool.
Before you start with adjustments, check the air filter and the spark arresting screen on the muffler. A dirty air filter or muffler will not allow you to properly calibrate the carburetor screws. Clean or replace them if needed.
Step 1
On the left side of the machine, you’d see two holes labeled L and H. These are the screws that you’d be operating on. If this is the first time you are meddling with these screws, you’d have to remove the caps off the screws.
Start by placing the blower on a flat surface. Remove the cover off the side of the blower by popping off the three screws holding it.
Step 2
Now, you should be able to access the rubber screw caps.
You should be able to pull off these rubber pieces with your pliers. If not, you can use a flat head screwdriver to give it a nudge. With the caps off, you should find the screws exposed.
Step 3
Make sure to start the engine and get it warm before making adjustments. Run it for 5 to 10 minutes and let it warm.
Step 4
Start by adjusting the high throttle screw which is on the left marked as H.
Turn the screw clockwise to increase the fuel flow. Turn the screw as much as you can clockwise until your blower is working at its maximum capacity.
Then, turn the screw anti-clockwise until you notice the engine slowing down.
Then, slightly turn it clockwise until it gains speed again so you hit the sweet spot with the fuel mixture.
Step 5
Do the same process with the L screw but this time do not hold down the throttle. Leave your engine at idle and turn the screw to the max clockwise. Slowly turn the screw anti-clockwise until the Engine RPMs start to dull.
Step 6
Finally, move towards the LA screw or idler screw. If the engine dies at idle, you need to turn the screw clockwise until there is enough fuel flow to keep the engine running smoothly.
Step 7
Finish up by getting the rubber screw guards back on the H and L screws and secure the cover back in place.