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.
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 chainsaw carb Related Question:
How do I know if my chainsaw is running lean?
If your chainsaw is running lean, it will take a long time to return to idle once you rev it up at a high rpm. Idle means the chain isn’t spinning even though the engine is on. Also, the saw will work at a higher rpm than recommended, but it will have less cutting power due to the lack of gas in the mixture.
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.
What does L and H mean on a carburetor?
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. The T screw regulates how much fuel is sent to the carburettor while idling until the throttle is pressed.
How do you adjust a running rich carburetor?
Regardless of whether or not the engine is running too rich or too lean, bring it down to a very lean mixture by turning both screws a quarter-turn at a time, counter-clockwise, then slowly bringing them back up to an equal and smooth mixture.
Why does my chainsaw not stay running?
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.
How do I know if my chainsaw carburetor is bad?
The carburetor might need to be replaced. To test the carburetor, remove the air filter, pour a teaspoon of fuel into it, and pull the starter rope. If the engine starts momentarily and then dies, the carburetor is likely why the chainsaw won’t start.
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 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 does a spark arrestor do on a chainsaw?
The spark arrestor on your chainsaw prevents dangerous hot sparks from igniting fires while you’re working. If the arrestor is clogged or dirty, however, it will also prevent exhaust from leaving the motor, which can prevent it from running.
Why does my chainsaw dies when I turn it sideways?
Because the fuel covers the jets. When the bar points down or the saw is held sideways the jets no longer have fuel to cover them, it is air. The saw then runs lean and dies.
What do the H and L screws do 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.
What is HL and LA on chainsaw?
On Stihl models with adjustable carburetors, the LA screw is accompanied by the L and H screws. These screws adjust the engine’s output at low and high speeds.
What does LA stand for Stihl?
One marked “H”, for high speed, one marked “L”, for low speed and one marked “LA”, which is your low speed air adjustment for idle.
How do I know if my carburetor is too rich?
Q: How Do You Tell if a Carburetor Is Rich or Lean? A: One way to tell for sure is by “reading” the spark plugs. If the plug tip is white, the mixture is lean. If it’s brown or black, it’s rich.
How do I know if my carburetor is too rich or lean?
This method involves looking at the base of the spark plug insulator (white part of the plug) for a slight coloring on the insulator just above where the insulator comes through the steel case. If the mixture is too lean, it will leave no color, while a rich mixture will cause the fuel ring to become more prominent.