If you have a new saw, this won’t apply to you, as new regulations require saws to be built so that only a qualified technician can tune the carburetor. If you have an older saw, here’s how to quickly tune it yourself. Less than five minutes of your time can make a big difference in how well your saw runs.
The correct carburetor adjustment will allow the saw to produce maximum power, extend the duty cycle of the engine, produce minimal smoke, idle smoothly, rev up nicely and give trouble free service. High Speed Fuel Adjustment – This is the adjustment that controls the proportion of fuel in the combustible air/fuel mixture at cutting speed. If carburetor adjustment is required due to a new or rebuilt carburetor, it is best to start with the fuel adjustment settings one turn out.
It would not be accurate to say this is the most important setting, because all of these adjustments need to be accurate for a saw to perform its best, but this is the adjustment that determines how the saw runs in the cut. If you adjust your saw with a dirty air filter, the saw will run too lean when the filter is cleaned. If proper adjustment for your saw is outside the limited range, take your saw into a shop.
Tuning the ChainsawSet the L&H mixture screws to manufacturers settings. Turn the Low mixture screw slowly clockwise with the engine running. Then turn the Low screw back clockwise until the fastest engine speed is achieved.
Begin with fresh fuel mix, clean air filter, check fuel filter, clean or new spark plug, clean muffler and spark arrestor. Begin with idle, L, and LH or T or whatever opens the butterfly and adjust until idle is steady and continues to idle when turned every which way but loose. If there is lag or hiccup, then adjust the L leaner, clockwise toward seat until idle and throttle response is acquired.
how to tune your chainsaw Related Question:
What is the H and L on a carburetor?
This adjustment controls the fuel flow to the low speed or idle circuit. If the carburetor is too far out of adjustment to run, or has been disassembled, start with turning the L and H all the way in and then open 2 turns on each needle. Then turn the TAS screw or idle speed adjustment in all the way.
Why does my chainsaw keep bogging down?
Many chainsaw operators first notice a problem with chainsaws bogging down when they’re using the chainsaw under load, and this is usually the result of poor air circulation. This issue is caused by a clogged air filter on the chainsaw. Remove the air filter from the chainsaw.
What are the L and H screws on chainsaw?
The letters on the screws represent High (H), Low (L) and Idle (T). The H screw regulates the Air/Fuel mix during high RPMs, while the L Screw does the same during low RPMs.
Why does my chainsaw only runs on choke?
When your chainsaw only runs if the choke is on the problem, in most cases, is a result of fuel supply problems or a faulty carburetor. To fix the problem you should check and clean the fuel system and carburator.
What do the high and low screws do on a chainsaw?
Most Pro Saw Engines Have Three Carburetor Adjusting Screws: If this adjustment is set too low, the engine will die when the throttle trigger is released. If this adjustment is set too high, the high idle speed will cause the centrifugal clutch to engage and the chain will run.
Why does my chainsaw stall when I give it gas?
If the filter becomes clogged, not enough fuel will reach the engine for it to run properly. Because your chainsaw will idle, but dies when it is revved up to full power, it means that the filter is only partially clogged; it will allow enough fuel to the engine to run on idle, but not enough to sustain full throttle.
Why does my Poulan chainsaw dies when I give it gas?
The carburetor might be clogged. A clogged carburetor is often caused by leaving fuel in the chainsaw for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and cause the chainsaw engine to stall.
Why does my chainsaw rev too high?
The throttle valve (butterfly) simply cuts off the supply of combustible air/fuel and the engine stops. If this adjustment is set too high, the high idle speed will cause the centrifugal clutch to engage and the chain will run. This is a dangerous condition and should never be allowed.
How do you fix a chainsaw that won’t stay running?
Clogged Air Filter – Check the air filter Your chainsaw’s engine needs the right supply of air to run properly. A clogged air filter can be the reason why your chainsaw won’t start or stay running. Find your chainsaw’s air filter and remove it. If it’s clogged or too dirty, wash it or replace it.
What is the La adjustment on a Stihl?
The LA setting on Stihl chainsaws is controlled by a screw on the outer housing of the engine that adjusts the flow of fuel and air through the carburetor. This screw is inside the engine housing on the carburetor, but is accessible through a hole or gap in the outer housing of the saw.
How do you use a tachometer on a chainsaw?
Record the engine speed with the tachometer. Look up your chain saw’s maximum safe speed in the operator’s manual. If the tachometer reads more than that speed, turn the “H” screw counterclockwise until the speed falls below the maximum safe speed value.
How do you start a stubborn chainsaw?
Try to start the chainsaw after priming the carburetor. 5. Activate the choke by moving the lever to the full choke position and pull the starter rope 3 or 4 times to start the engine. If that doesn’t work, move the choke lever to half choke and pull the starter rope, 6 times maximum, to start the engine.
Will a chainsaw run without a fuel filter?
While it’s possible to run your chainsaw without a fuel filter, but this is not recommended. When a fuel filter is clogged, it can cause considerable damage to the engine and leave your chainsaw unusable.
What is choke on a saw?
The choke position is the fourth setting on the master control lever. This setting is used to start the saw when its motor is cold. Stihl chainsaws denote the choke position using a nearly horizontal squiggle between two vertical lines at the lowest position on the master control lever.
How do you adjust a Stihl carburetor?
Turn the H screw clockwise with a carburetor adjustment tool until the head is spinning as fast as it will go, then back off the screw carefully until the RPMs start to decrease. Turn the screw slowly clockwise again until the engine once again just starts to pick up speed.