Carburetor Chainsaw Adjustment Screwdriver

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Husqvarna carburetor screwdriver

Carburetor adjustment of the Husqvarna 128R.

The first question that should be answered in the title topic review. Why is it necessary to adjust the carburetor of the 128th braid? It is all about European fuel standards. The 128R petrol scraper is configured to meet EU fuel standards. We have lower quality fuel (we are discussing AI-92 gasoline), which makes this adjustment necessary.

The procedure for adjusting the Husqvarna 128R carburetor is not complicated.
What you need for its production is a rev counter tachometer, adjusting screwdrivers.

1. We set the departure of fishing line from the trimmer head 15 cm long on each side (this significantly affects the speed).

2. We dilute AI-92 gasoline with Husqvarna engine oil for two-stroke engines in a ratio of 1:50 (one part of oil to 50 parts of gasoline). For ease of calculation, we recommend a ratio of 1 liter of fuel x 20 milliliters of oil. For the first start of the braid, we recommend a ratio of 1 liter of fuel x 23 milliliters of oil (ratio for engine break-in). Exact observance of these ratios and the use of only Husqvarna oil for two-stroke engines is the key to long-term operation of the engine and the supplier’s warranty in the event of a warranty case.

3. We start the scythe and bring it to the maximum speed with the throttle stick. With the right adjusting screw N we adjust the revolutions to the level of 8500. 8800 according to the tachometer.

4. Release the throttle stick. At idle speed on top of the carburetor with the adjusting screw T, we bring idle speed to the level of 3000. 3200 by tachometer. In this case, the motor should work smoothly, without jerking. The trimmer head should stop rotating.

5. In case of visible smoke from exhaust gases or unstable idling at set idle speed. Adjustable “mixture quality” left carburettor adjustment screw L.

Have trouble adjusting the carburetor for the Husqvarna 128R?- Bring her to our service center. We will help you.

The practice of servicing the Husqvarna gas tool at our service center has shown that the need for adjustment arises periodically for other Husqvarna chainsaws and lawn mowers. Adjustment data, by analogy with the procedure described for adjusting the carburetor of the Husqvarna 128R trimmer, can be performed by any user independently. Below, for reference, we give the engine speed indicators for various equipment and in various modes.

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Husqvarna 5300355-60 carburetor chainsaw and carburetor adjustment screwdriver

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Husqvarna chainsaw carburetor adjustment

Husqvarna chainsaw (Husqvarna) 137. Carb adjustment.

The best advice that I can give you is to consult a specialist! Believe me, for very little money, specialists will adjust the carburetor, check the general condition of the saw. But if you still need to spend carburetor adjustment on a saw Husqvarna 137 yourself, then I will try to describe this process in detail. Also at the end of the post I added a about how adjust carburetor chainsaw at idle.

Adjustment and tuning of the carburetor Husqvarna 137

Husqvarna137. Carb adjustment

In the picture above, you see three screws for adjustment. Each of them has its own purpose:

Screw T is needed to adjust idle speed.

Screw L is used to adjust low revs.

Screw H adjusts high revs.

Adjustment Procedure:

First, screw L (turning it) we are looking for the highest idle speed. After we found them, you need to turn this screw a quarter of a turn against the clock. If in this position the circuit continues to rotate, then by rotating the screw T we achieve its stop.

Then we warm up the engine at full speed in the region of 10-15 seconds and turn the screw H a quarter counterclockwise. We wait 10 seconds and listen, the engine should work as a 4-stroke sound. If a squeal is heard, then the mixture is poor (unscrew the screw), if the enriched mixture smokes (we twist the screw).

After adjusting the low and high revs, set the idle speed with screw T. This is done as follows:

1. The engine should work

2. Turn the screw T clockwise until the chain starts to rotate.

3. Turn the screw to the other side until the chain stops.

With a properly adjusted carburetor, your chainsaw quickly picks up speed and sounds like a 4-stroke engine.

Remember that a tachometer and experience are required to properly adjust the chainsaw carburetor. Therefore, it is better to contact a specialized service!

DIY carburetor adjustment on a chainsaw

Adjusting the carburetor of the chainsaw ensures efficient operation of the tool at full power with economical fuel consumption. Adjustment should be made with a clean fuel and air filter. For a larger number of carburetors, the adjustment is carried out by three screws: for maximum and minimum speed and idle adjustment.

Screws H and L adjust the ratio of the gasoline-air mixture determined by opening the carburetor throttle. When the screws are loosened, the mixture is enriched, and the revolutions accordingly fall; when the screws are twisted, the mixture becomes leaner. The revolutions increase.

The designation H refers to the maximum speed screw that controls the main jet, L to the minimum speed screw that controls the idle jet. Screw S provides precise idle speed control. Sometimes, to simplify the adjustment, the number of carburetor adjusting screws available is reduced.

Setting the carburetor of the chainsaw is divided into two stages. Basic (factory settings), carried out with the engine turned off. And final, produced on a running warm engine. The exact angle of rotation should be taken from the operating instructions for the particular chainsaw. Failure to follow the manufacturer’s instructions could result in engine damage.

Basic carb adjustment.

The adjusting screws for the maximum H and minimum L revolutions are slowly turned clockwise until they stop, after which they are turned back 2 turns, other settings are also possible

Check and adjustment of idling.

We find the highest idle speed, for this, slowly turn the screw L in different directions.

5300355-60 Husqvarna carburetor adjustment screwdriver. Husqvarna

After finding the position of the highest engine speed, turn screw L 1/4 turn counterclockwise. If the chain rotates at idle, screw T or (S) should be turned by turning it clockwise until it stops.

Checking and adjusting the maximum speed.

Changing the maximum number of revolutions is carried out by screw H. When it is screwed in (clockwise rotation), the speed increases, when turned out, it decreases. Chainsaw engines have the highest rotation speed of 11,500 rpm. Up to 15000 rpm Ignition does not provide a higher speed, in addition, it becomes dangerous for the engine. The maximum speed can be determined by interruptions in the ignition. If they come, screw H is slightly turned counterclockwise.

If the engine is not tested for acceleration and maximum speed, then the adjustment of the chainsaw cannot be considered complete.

With a smooth pull of the gas trigger, the engine must confidently and quickly gain speed from idle to maximum (from 2800 rpm to 11500-15000 rpm depending on the unit). If the speed is slow, delayed, screw L must be slowly turned out counterclockwise, but no more than 1/8 turn.

After adjusting the acceleration and maximum revolutions, you should again check the operation of the saw at idle. The engine should work stably, the chain should not move. Chainsaw setting should be repeated if this condition is not met but with the exception of the basic adjustment step.

Chainsaw Carb Adjustment

Carburetor Chainsaw Adjustment Screwdriver

The carburetors of most chainsaws have three adjustment screws:

  • L. Jet screw for low speed adjustment
  • H. Jet screw for adjusting high revs
  • Screw. T at the Partner and Husqvarna (at Calm LA ). Chainsaw idle speed adjustment

Screws H and L adjust the ratio of the gasoline-air mixture determined by opening the carburetor throttle. When the screws are loosened, the mixture is enriched, and the revolutions increase accordingly; when the screws are twisted, the mixture becomes leaner. The revolutions fall.

Screw T (LA) is used to adjust idle speed. The main setting of the chainsaw is made at the factory during the final test. The carburetor, as a rule, is adjusted to supply a richer (than optimal) fuel mixture. Factory adjustment is necessary to keep the first hours of operation of the saw. Then (optionally) a more accurate carburetor adjustment is made.

We begin the adjustment by setting the idle speed, for this we turn the T (LA) screw counterclockwise, achieving a complete stop of the circuit at stable engine speeds.

For further fine adjustment, you need a tachometer and it is better to entrust it to specialists. Especially since in most cases it may not be needed.

We begin the tool setting with screw L, then use screw H and finally screw T (LA).

We find the highest idle speed, for this, slowly turn the screw L in different directions. After finding the position of the highest engine speed, turn screw L 1/4 turn counterclockwise. If the chain rotates at idle, screw T should be turned by turning it clockwise until it stops.

Screw N adjusts the power and speed. Adjusting the carburetor to lean mixture leads to excess revolutions, overheating of the engine and failure of the piston chainsaw.

We warm up the engine of the chainsaw at idle for at least 10 seconds and turn the screw N 1/4 turn counterclockwise. Let the engine run for about 10 seconds. Then check the maximum engine speed with a tachometer. If the maximum speed does not match the passport, the operation should be repeated. If the mixture is too rich, the muffler starts to smoke, when the saw is too poor, the saw squeals and overheats.

We finish the adjustment by setting the idle speed, as already described above. The idle speed is set correctly if the engine runs smoothly at minimum speed and the chain does not rotate.

A carburetor can be considered adjusted if the engine accelerates quickly and resembles a four-stroke full-throttle sound.

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Fuel system and lubrication system of the Husqvarna 365, 372 chainsaw

Carburettor adjustment involves adjusting the engine to local conditions, such as climate, altitude, gasoline quality and type of oil for 2-stroke engines.

The Husqvarna 365, 372 XP chainsaw carburetor is equipped with three control options:

L = Low speed jet.N = High speed jet.T = Screw for idle adjustment.

With the L and H jets, the amount of fuel is regulated so that it matches the air flow supplied by the throttle of the gas handle. If the jets are screwed in clockwise, the mixture will be poor (less fuel in relation to the amount of air), and when unscrewing the jets counterclockwise, the mixture will be richer.

A lean mixture produces higher rpm, while a richer mixture produces lower rpm. Screw T adjusts the position of the shutter at idle. If the screw T is turned clockwise, the number of idle turns will increase, and if you turn the screw counterclockwise, the number of turns will decrease.

Pre-adjustment and running-in

When checking the work at the factory, a preliminary adjustment of the carburetor was performed. Preliminary adjustment: N = 1 revolution, respectively L = 1 revolution.

In order for the engine parts of the Husqvarna 372, 365 XP saw to receive sufficient lubrication (break-in), the carburetor is set to slightly increase the enrichment of the fuel mixture for the first 3-4 hours of operation. For such an installation, the maximum number of revolutions is set at 6700 rpm below the recommended one.

If it is not possible to check the maximum number of revolutions with a tachometer, then jet N must not be installed on the fuel mixture below the preset.

It is forbidden to exceed the maximum number of revolutions. If the chain of the chainsaw rotates at idle, then by turning the screw T counterclockwise, it is necessary to achieve its complete stop.

Fine carb adjustment

After running in the Husqvarna 365, 372 XP chain saw, it is necessary to fine-tune the carburetor. First you need to adjust the nozzle L, then the idle screw T and then the nozzle N. The following maximum number of revolutions is recommended: 12500, at idle speed 700 rpm.

During adjustment, the air filter must be clean and the cylinder cover in place. When adjusting a carburetor with a dirty air filter, the fuel mixture will be too lean when the air filter is cleaned or replaced next time. Too lean a mixture will damage the engine.

Carefully tighten the nozzles L and H to the bottom and then unscrew them 1 turn. Now the carburetor is set to H = 1 and L = 1. Start the unit and let it run for about 10 minutes.

Place the model 365, 372 XP chain saw on a flat surface so that the saw bar is facing away from you and that both the bar and chain are in contact with the surface.

Low speed jet L

Find the maximum idle speed by slowly turning the low-speed jet counterclockwise and, accordingly, counterclockwise. When the maximum number of revolutions is found, turn the jet L counterclockwise by 1/8. 1/4 revolution.

Fine tuning idle screw T

The idling is carried out by the screw marked T. If adjustment is necessary, the idling screw T should be turned clockwise until the chain starts to rotate. Then turn the screw counterclockwise until the chain is stationary. Correct is considered such a number of revolutions at which the chainsaw engine runs smoothly in all positions with a sufficient margin to such a number of revolutions at which the chain starts to rotate.

High speed jet N

The high-speed jet N controls the power and the number of revolutions. A mixture that is too lean on a high speed jet gives increased tool revolutions and creates a risk of engine damage. Run the unit at full throttle for 10 seconds. H = 1. Then turn the screw H 1/4 turn counterclockwise. H = 1 1/4.

Then let the chainsaw run for another 10 seconds and listen to the difference in sound at maximum speed. Repeat the procedure with adjusting screw H turned 1/4 turn counterclockwise. H = 1 1/2. Now the tool works at Н ± 0, Н = 1/4 and Н = 1/2, based on the preset. At full throttle, the sound of the engine will be different for each installation.

Jet N is considered to be correctly installed when the unit operates with little noise at full throttle without load. If a lot of smoke comes out of the muffler and the instrument is noisy, then the mixture is excessively rich. Turn jet H clockwise until you get the setting with the correct sound.

Correctly adjusted carburetor

The carburetor is correctly adjusted when the saw is gaining momentum confidently and when it is working with little noise at full throttle without load. The chain should not rotate at idle. If the mixture is excessively lean on the nozzle L, engine start-up may be difficult and it will be poorly gaining speed.

When installing nozzle H on an excessively lean mixture, the power of the tool will be lower, it will not gain speed well and / or this may damage the engine. An excessively rich mixture on the L and H jets creates problems when gaining speed or gives too low working speeds.

Fuel tank unit

Drain the fuel tank. Remove the cylinder cover, chain and saw bar.

Unhook the gas cable (A) from the carburetor and push the cable cover out of the mount. Remove the fuel hose (B) from the carburetor. If the saw is equipped with a handle heater, remove the cable near C. Loosen the screws (C and D) and the motion restriction screw (E) on the clutch side of the Husqvarna 365, 372 XP chainsaw. Remove the bolt on the flywheel side.

Lift a few engine compartments using pliers and push the cable terminals off the stop contact. If the model is equipped with handle heating, also remove the cable terminals from the stop contact. Lift the engine compartment and rotate the fuel tank compartment slightly toward the flywheel so that the locked motion stop is released and remove the fuel tank compartment.

If necessary, unscrew the handle bracket from the fuel tank compartment. If necessary, remove the fuel hose and remove the fuel filter of the chainsaw. If the saw is equipped with handle heating, remove the contact of the heater coil in the handle. Clean all parts and check that the fuel hose is intact. If the saw is equipped with handle heating, mount the heater coil in the handle if it has been removed.

To install a new fuel hose, proceed as follows: Lightly oil one half of the new fuel hose. Press the oiled part of the new hose through the hole in the fuel tank compartment. 80-85 mm should go up out.

Turn the hose so that it is bent up. Cut off a portion of the wedge-shaped hose at both ends of the hose so that the hose extends upward by about 70-75 mm. Remove the hose from the fuel tank and fit the fuel filter. Put on the hose as far as possible.

If the handle bracket was removed, then mount the bracket. Tighten the screws with a force of 4 Nm. If the gas lock has been removed, reinstall it before the fuel tank compartment and engine compartment are assembled together. Lift the engine compartment above the fuel tank compartment and insert the fuel hose and gas cable into its holes in the bottom of the carburetor chamber. Install the stop contact cables.

Fold the fuel tank compartment slightly toward the flywheel so that the locked travel stop is in the correct position.

Husqvarna Chainsaw Carburetor Adjustment Wrench

Fit the screw (F) on the flywheel side. Tighten the screw to 6 Nm. Mount the screws (C and D), the chain catcher and the travel restriction screw (E) on the clutch side. Tighten the screws.

If the saw is equipped with a handle heater, mount the cable near C. Install the fuel hose (B) on the carburetor. Insert the carburetor into the casing and hook the gas cable (A) on the carburetor. Fit the cylinder cover, chain and saw bar.

The lubrication system of the Husqvarna 372, 365 XP chainsaw consists of the following parts:

Removal and installation

Remove the following parts: Chain and saw bar, Centrifugal clutch, Chain brake. Unscrew the drive wheel.

Use a screwdriver and push up the oil pipe near A. Open the pipe up and pull it out of the oil pump. Remove the two screws (B) and remove the oil pump from the crankcase.

Use sharp pliers and pull out the suction hose (C) with strainer. Remove the clamp (D) and unscrew the adjusting screw (E).

Using pliers, push the oil pump piston near F so that the plug (G) and pump piston (H) can be removed. Using pliers, remove the spring (I) and 2 washers (J).

Clean all parts, including the mounting plate of the oil pump and oil hose, and check that there is no wear on the cone of the adjusting screw (E), the eccentric plate on the pump piston (H) is free of wear, the pump piston gear is not damaged, and the worm gear drive the oil pump was intact, the oil hose was not dirty and so that the sieve was clean, the oil pipe was clean and that its seals were free of damage.

Insert the suction hose (C) into the hole in the crankcase. Install the spring (I), 2 washers (J), and the pump piston (H) in the pump housing. Lubricate all parts with saw chain oil. Use a screwdriver and press on the oil pump piston, and screw in the adjustment screw (E) to the bottom. Fit the overlapping plug (G). Fit the clamp (D).

Mount the oil pump in the crankcase. Tighten the screws with a force of 5 Nm. Fit the oil pipe with gaskets. Spin the drive wheel. Fit the following parts: Chain brake, Centrifugal clutch, Chain and tire. Adjust pump power. Add chain oil to the tool and check the lubrication. Adjusting the power of the oil pump. The power of the oil pump is regulated by the adjusting screw (E).