When do you need to adjust the carburetor??
The reasons why this assembly needs adjustment can be listed for a long time. Among the main faults are the following:
- Increase of revolutions at idle;
- A large amount of smoke appears during operation;
- Deterioration of starting ability;
- Not enough power to the tool when cutting.
This is not a complete list of all known faults. Sometimes such a procedure as adjusting the carburetor on a Husqvarna chainsaw, it is necessary to carry out after a major repair of the power unit or after maintenance.
Developers Husqvarna 137 write in the passport that the carburetor must be adjusted before and after running-in the tool.
The basic package of Husqvarna 240 chain saw includes the following components:
- fuel pump and fuel tank;
- rear and front handle;
- saw blade;
- Saw chain, chain stop and chain catcher;
- universal wrench;
- instruction manual;
- blade guard.
For a full list of chainsaw parts and accessories please refer to the instruction manual. This model is manufactured and assembled by Svensk Maskinprovning AB (Sweden). The saw complies with EU requirements for household appliances in terms of noise level and technical features.
, depending on the retailer. In Ukraine you can buy such a saw at a price of 5,600 to 8,000 hryvnia, in the U.S. the Husqvarna 240 model currently costs from 180 usd.
Husqvarna 137/142 chain saw oil seal replacement. Photo report
Many villagers, as well as dacha owners, farmers and owners of large homesteads have a Russian or imported chainsaw in their arsenal. The chainsaw is a simple, rugged tool with a single-cylinder, two-stroke carburettor engine that can be used for anything from building work to chopping wood and taking care of trees and shrubs. The chainsaws are purposefully designed to be as simple as possible so that users can carry out maintenance and repair work themselves when they are far from large cities or authorized service centers. In addition to many other important operations, such as changing and adjusting spark plugs, cleaning the fuel filter and muffler, chainsaw service and repair includes lubricating or replacing bearings. Since these play a major role in keeping your chainsaw running, they are one of the most important maintenance items you have to pay attention to.
How it works
Almost all foreign (Husqvarna, Makita, Shtil, Partner 350) and Chinese chain saws, as well as domestic ones (Druzhba, Urals) are organized in the same way. Therefore, it is not very difficult to find the reason why the device does not start and stop.
There are four elements where problems can occur:
- Fuel, which the carburetor is responsible for;
- Air, which comes through the air filter;
- The spark, the quality of which depends on the ignition unit.
They all depend on each other and interact with each other. If any element is not working properly, the saw stops working.
To begin with, all tools are set up differently. hot and cold. Two frequently used mechanisms are responsible for this process.
Don’t forget to look at what’s written in the owner’s manual. It says that when you turn it on, you need to make sure that the emergency stop brake is engaged. But it’s much harder to start a saw with the brake, so sometimes it’s better not to engage the brake.
As you can see from the manual, there is a fuel tank and engine inside the body, and outside. saw section (guide bar with chain), handle and starter.
First we need to find out exactly how the tool does not start. For example, the saw starts, but immediately catches the eye or loses the power of the work, the quality of cutting.
Husqvarna Bench Saw Crankshaft Seal Replacement
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Clutch design, principle of operation
In order to successfully disassemble this assembly, you will need a chainsaw clutch puller. But before we consider how to use it, let us study the features of the device of this functional part of the power unit.
Husqvarna & Stihl Chainsaw Crank Bearing Replacement & Case Assembly. “Clips From The Archives”
Pay attention to the fact that in the development of modern chainsaws, manufacturers most often resort to the use of a centrifugal clutch. And that tells you that the tool and its operation depends on the torque reserve that the equipment provides here and now.
The main structural parts of this unit include:
As for the principle of operation, everything is simple.
- As soon as the chainsaw is put into operation, the clutch springs will pull all the freely moving elements (moving in the radial direction) toward the axle.
- At this point, no torque will be transmitted to the guide with the sprocket.
- As soon as the centrifugal force becomes higher than the force potential of the spring, all freely moving attracted elements will loosen and squeeze inside the drum, which starts it (it starts spinning).
- The rotation is transferred to the guide bar and the main sprocket.
This is the principle of the centrifugal clutch that has several advantages over other variants. Among them is the absence of motor stoppage when the cutting element is abruptly braked (i.e., the clutch slips). Due to this feature of the mechanism, the main unit of the chainsaw remains unharmed.
Note that this type of clutch will operate automatically. Its function depends on the number of revolutions of the engine. The movable elements inside the drum will be drawn to the shaft (its center) even at minimum rpm. This plays an important role in preventing serious tool failures. When this mechanism fails, then there is a need to figure out how to remove the clutch on the chainsaw.
Peculiarities of maintenance and self-repair of chain saws of Husqvarna brand (Husqvarna)
Husqvarna started in 1689. Husqvarna started to manufacture saws in the early 1920s. Nowadays the Husqvarna chainsaw range is so big that we had to write a separate article to describe the main models. Here’s an in-depth overview of Husqvarna chainsaws and their devices.
How to adjust the carburetor on a Husqvarna 365 chain saw
To adjust the Walbro HD 6B, there are three screws on the carburetor housing:
Tuning the carburetor of the Husqvarna 365 chainsaw can be divided into two stages: preliminary tuning, fine tuning.
The adjustment of Husqvarna 365 carburetor can be made through special holes in the body of the saw itself (the location is marked on the photo above).
Presetting. At the factory, during the chainsaw test, basic carburetor adjustments are made. The basic setting is as follows: H. 1 revolution, L. 1 revolution.
After buying a chain saw it is necessary to bring the engine into full operation. For this purpose, it is necessary for the engine to run on a rich mixture for the first 4 hours. To ensure this mode, it is necessary to adjust the maximum revolutions 600-700 rpm below the maximum, this is about 11800 rpm.
Please note! The maximum rpm of the Husqvarna 365 chain saw should not exceed 12500 rpm, otherwise the cylinder and piston group could suffer excessive wear and tear and even be damaged.
Fine Tuning. After the run-in of the chainsaw it is necessary to fine tune the carburetor. First you have to adjust the L screw, then the T screw and only then the H screw. Before adjusting it is recommended to start the chainsaw engine and warm it up for 10 minutes.
The algorithm for fine adjustment of the carburetor is as follows:
- Adjusting the L jets. Try to find the maximum rpm by turning the L screw clockwise or counterclockwise (for a more accurate determination, use the electronic tachometer). when you have found RPM you should turn back the L screw by 1/4 turn.
- set the engine idle rpm with the T screw. turn the T screw to find recommended by the manufacturer idle speed. 2700 rpm. when the rpm is found, turn the screw T until the chain does not rotate any more. achieve a mode where the engine starts to run smoothly from any position and when the throttle is released the chain stops rotating.
- Adjusting the H nozzle. Turn the screw H as far as it will go and turn it back 1/4 turn. let the saw work at maximal rpm for 10 seconds. Watch the character of the sound. if you hear whistling at full rpm, it means the mix is too weak. In this case the screw H needs to be loosened by 1/4 turn more. If the tuning is correct the high RPM gives a little “quadruple whistle” (the exhaust sound is similar to that of a four-stroke engine). If the saw “quadruples” a lot and has a lot of smoke, then the mixture is too rich. In this case the screw H needs to be tightened a bit. Turn the H screw until the engine sounds right.
When the carburetor is set up correctly the chain saw runs smoothly and has a slight “quadrant” at full throttle. The chain does not rotate at idle. When the throttle is opened sharply, the saw revs up smoothly, with no dips.
It’s the one wand of choice in many situations, so it’s never ignored in our reviews. It does not look intimidating: only 32 pages, two of which are blank for personal notes. No traces of translation by electronic systems, but in two places there are still phrases that hurt the eye a little, such as “the spark plug does not ignite”.
Nearly one-third of the instruction manual is about safety while working with the Husqvarna 142 chain saw. A pleasant surprise was the description of the techniques of working not only with trees, but also with limbs: detailed diagrams of safe creation of cuts are presented. The influence of the shape of the bar end on the rebound probability is very clearly explained.
The characteristics of the 142 Husqvarna are presented in full with a small caveat. Only one model of Champion spark plugs used is listed. But nowhere is it explicitly written that using any other models is categorically forbidden due to design features. As a rule, the manufacturers either indicate several suitable models, or describe the characteristics of the required candles in detail. That’s why the section describing the ignition system could be more informative. This remark is not fundamental, because experienced owners know how to use specialized manufacturer’s catalogs and find in most cases an analogue of any candle.
The assembly sequence of the Husqvarna 142 chain saw is described in detail with a detailed explanation of the drawings.
Particular attention is paid to self-correcting minor problems that arise in the process of work. How to troubleshoot problems that cause a Husqvarna 142 chain saw not to start or to start and stop is described in great detail. And this section, which describes the carburetor tuning, could be more informative. In particular, for adjusting the mixture quality, it says what to turn, but the criterion for the end of adjustment is not clearly stated.
In general, the instruction manual of Husqvarna 142 chain saw is convenient and contains the minimum necessary knowledge on operation and repair.