Chainsaw homelite csp 4016 carburetor adjustment

Setting the chainsaw carburetor: adjustment of different models (features)

On its way from the fuel tank to the combustion chamber, the fuel mixture bypasses a very important element of the system. The carburetor, which provides a regular supply of “nutrient” to the engine, has a particular impact on the chainsaw’s performance. Even a small fault in the fine tuning of the tiny mechanism of this device, causes marked deviations in the work of the entire tool, reducing efficiency and increasing fuel consumption. In this lesson you will learn how the adjusting screws affect the system and how to achieve their optimal position.

The more you understand how it works, the easier it is to operate, service or repair. The carburettor mechanism is quite complex and works with several adjacent assemblies (crankcase, gas pedal and tank). It is actuated by jolts of air wiggling the diaphragms, but more about that and in due course. For now, let’s consider the device in general.

As it should be the “heart” of the fuel system, the carburetor design is not simple, but can be understood with smooth and consistent disassembly. Let’s start with a general list and go straight to the interaction of components. Depending on the model, the mechanism may include about 20 parts, the location of which is clearly illustrated by the following diagram of the carburetor chainsaw modern sample (actual since 90s).

• Fuel connection. Connects to the hose coming from the tank.
• Pulse channel nozzle. Connects to the engine crankcase through which air is displaced and drawn in, affecting the diaphragm.
• Fuel Pump Diaphragm. Performs the function of pumping the fuel into the chamber and then feeding it into the fuel channel.
• inlet valve. Controls mixture flow by allowing it to enter the diaphragm chamber and restricts movement back.
• Exhaust valve. In terms of functionality, it is identical to the previous part, but it provides control of the flow from the diaphragm chamber to the fuel channel.
• Filter element. Final stage of fine fuel separation. Designed as a fine mesh screen.
• Fuel line. Makes sure the mixture is delivered to the bottom of the carburettor.
• Needle. Blocks the fuel line without allowing mixture to flow back to the top end of the machine. Functionally similar to the valves, but more complex.
• Control diaphragm. Acts on the needle through a spring-loaded lever mechanism, changing its position depending on the amount of fuel in the chamber.
• High RPM adjustment screw (H). Connected to a needle with a tip that restricts flow to the stroke and nozzle nozzles.
• Stroke nozzle. Provides a metered supply of mixture to the atomizer.
• Idle speed adjustment screw (L). Identical in structure and function to the preceding screw, but the needle restricts the flow capacity of the conduit to the other 2 outlets.
• Middle (left) and idle jets (right). Technological orifices that regularly inject the mixture into the air mixing chamber.
• Air damper. Auxiliary component required for cold engine start. Is always in the open position when in operation.
• Throttle valve. Adjusts the volume of fuel mixture intake into the mixing chamber. Actuates only 1 idle restrictor in closed position; when open, activates 2 remaining throttles in turn.
• Diffuser. The narrowing part of the main channel of the carburetor, where the fuel and air mix. Specific shape for greater airflow rate.
• Fuel cell. Fuel mixture accumulation place, where it is fed by the diaphragm pump and from where it is distributed by passing through the nozzles into the mixing chamber.

The mixture starts its high-speed route through the fuel system of the tool, starts from the gas tank, from where it is sucked through the filter and flows through a hose, through a nozzle, into the fuel pump chamber, passing the inlet valve. As the engine piston rises, the air in the sealed crankcase is compressed, pressing the diaphragm against the top cover, to which it is connected through an impulse hose (this is how gasoline is pumped). When the piston goes down, the pressure in the crankcase rises and bends the diaphragm in the opposite direction, directing the accumulated mixture in the chamber through the only path available, through the exhaust valve into the fuel channel.

Before entering the fuel chamber, fuel flows through the cone-shaped needle tip, pressed to the nozzle by a spring, through a channel of the same name. The position of the needle is controlled by the control diaphragm, which retracts into the carburetor when a vacuum is formed, pushing the tip back and allowing the mixture to enter the chamber. On filling (even partial) the vacuum attenuates and the spring presses the needle again closing the passage.

From the fuel chamber, the mixture is directed to the nozzles, passing through the technical openings, the width of which is adjusted with screws (L and H). At the outlet of the nozzles, the fuel is picked up by the air stream and atomized into small particles. When the throttle is closed, fuel is drawn only from the last orifice (idle stroke) closest to the engine. When the throttle trigger is pressed smoothly, the flap opens, gradually increasing the activity of the adjacent nozzle (middle stroke). In the maximum position, the outermost nozzle is engaged (high stroke), increasing the volume of fuel delivered and the speed of the piston movement, accelerating the entire system.

Tuning tools

Like any maintenance procedure, adjusting a chainsaw requires certain tools that allow you to interact comfortably and efficiently with the mechanism. Fortunately, the basic arsenal for such an event, consists of only one slotted screwdriver with a long rod. Relevant for 95% of carburetors, domestic, amateur and professional chainsaws.

Maximum fine tuning is done with a special electronic device that reads the speed of the crankshaft. If you want to get the best result, it is better to buy a budget tachometer and figure out how to measure chain saw’s rpm by simple and effective method. The device is not very useful for experienced users, who can tell the difference by the sound of the defects, but for beginner sawyers, it can help a lot.

Some manufacturers overly unique their products, equipping them with elements with a non-standard design. For example, adjusting the carburetor of a Husqvarna 135 or Jonsered CS2238 chain saw requires a screwdriver with an extremely unusual shape, which you can not get everywhere. This complicates the procedure of self-adjustment and makes it necessary to apply to a specialized service center. service. If your saw has unusual screw heads on the carburetor but you want to do the adjustment yourself, it is better to order the required tool in advance (you can find it on ali and some online stores).

What is needed to correct the problem

Before you begin disassembling and repairing your chainsaw, have the right tools and supplies ready:

Chainsaw malfunctions can be of two kinds:

The following indicators will indicate that an engine diagnosis is needed:

• The tool won’t start or starts and stops.
• Is not running smoothly.
• It idles, but rpm drops or stalls under load.

Ignition system (won’t start, stalls)

Check spark plug appearance.

Fuel system

• There is a hole in the fuel tank cap that may have become clogged. If this happens, a vacuum has formed that prevents the fuel from flowing.
• Fuel filter in the tank. The spark plug becomes fouled over time.
• Fuel does not flow properly from the carburetor to the cylinder.

The first two causes are identical. To do this, disconnect the hose through which the fuel flows from the carburetor. And check how much air comes out. If it leaks weakly or not at all, clean the tank cap with a needle and replace the fuel filter. But first you have to drain the fuel mixture and use a wire hook to pull the filter out of the tank. If the fuel flows well from the disconnected hose, the air filter is clogged or the carburettor is faulty. The air filter affects the air flow to the carburettor and the fuel mixture enrichment. When it is clogged, the mixture is too enriched because no air is coming in. It affects the proper functioning of the engine.

• Carefully remove the air filter so that the dust does not scatter. Cover the opening in the combustion chamber with a clean cloth.
• Blow out the filter and clean with a soft brush. If the filter is not cleaning, flush it. After drying, put it back.

Before you start adjusting the carburetor, check that the air filter is clean and the chain is tight enough. Read the instructions. The manufacturer describes how to properly adjust the carburetor. If there is no manual, find the three marked screws:

Take the carburetor adjustment screwdriver and proceed.

• Basic adjustment. Performed with cold engine off. Turn screws H and L all the way to the right, i.e. clockwise. Then a turn and a half to the left.
• Idle speed adjustment. Run and warm up the engine before starting. Turn the propeller S to the right to increase RPM and to the left to decrease RPM. You need to slow down the engine rpm and make sure it runs steadily, without pauses. Make sure the chain doesn’t move. If the engine suddenly stops, increase RPM little by little. And when you move the chain, reduce the.
• Checking the engine for acceleration. Smoothly press the fuel button. A tuned engine should quickly and confidently gain revs to the maximum. If the engine hesitates or lags, turn the L screw to the left no more than an eighth of a turn.
• Adjusting Maximum RPM. Ignition failure occurs at maximum rpm. Turn screw H slowly to the left until stable.
• After all the adjustments are complete, check that the engine idles. It should run stable when the chain is stationary. If you do not achieve the desired result, repeat all adjustments, excluding the basic.

Muffler Disassembly and Cleaning

When the muffler is clogged, the exhaust fumes have nowhere to go. The saw will not run or start. The chainsaw is designed so that the muffler can be removed quickly. Depending on how it is fastened, you may need a hex wrench or socket wrench.

The muffler becomes clogged due to poor-quality oil or improperly mixed fuel.

Cylinder and piston assembly

Wear and damage to the cylinder and piston assembly may result in an inability to start the engine.

Remove muffler to detect damage. You will open the exhaust port, in which you will see part of the cylinder surface.

In addition to the piston, which may have no damage visible in this hole, inspect the piston ring. If the defects are present, you need to disassemble the entire piston group to fully assess its condition. Faults can only be corrected by replacing the band completely.

• Get a pressure gauge to measure compression. Screw it into the spark plug hole, gently pressing on the sealing rubber.
• Yank the starter while watching the gauge arrow.
• The pressure should be at least 8 atmospheres.

If you don’t have one, try the folk way. Unscrew the spark plug.

Plug the spark plug hole with your finger and yank the starter. If the finger is sucked in, there is compression.

Chain, tire

Cracks, chafing and chipping of rivets and link sides.

The cutting link is so worn that it’s hard to saw.

After replacing 3 chains, change the tire and drive sprocket.

Chain saw chainring sprocket

To replace the sprocket you will need: a spark plug wrench, piston stopper, clutch puller.

• Remove the cap to access the spark plug. Unscrew spark plug with wrench.
• Use the clutch puller to turn the clutch clockwise until the piston reaches the top dead center. This can be checked through the spark plug hole.
• Screw in piston stopper instead of spark plug. If not, twist thick rope string and put it in the spark plug hole.
• Use the clutch puller to turn the clutch to the right and unscrew it.
• Remove all parts of the clutch assembly and the sprocket plate in sequence. Replace it with a new one.

Chain lubrication system

If the bar is not lubricated or is poorly lubricated, the chain and bar will overheat, causing severe friction and wear. Check the holes and passages through which lubricant flows. If they are clogged, they must be cleaned.

• There are cracks in the oil pump housing. In this case, the pump needs to be replaced.
• Leaking pump and tube connection.
• Tube is cracked.

All chainsaws have an oil adjustment. Next to the location of the adjusting screw on the body is always marked in the form of a chain link and an oil drop. If you turn it to the right, the oil flow decreases. oil in winter and less in summer. Do not decrease the oil volume too much, otherwise the tire will burn.

Homelite CSP 3314. Model Features

This Homelite chainsaw has a low weight of only 4.5 kg. The tool weighs up to 5.2 kg when finished., That allows it to be used in high-altitude work. The chainsaw is built with a gasoline engine, safely hidden under a rugged housing.

The body has one front and one rear handle for more convenient operation. The tool stops its operation with a handbrake. The engine is started with the starter rope handle.

A distinctive feature of this model is the presence of a special device called Safe-T-Tip, which is designed to throw dust away from the operator. This accessory can be removed if you wish. Key tool specifications include:

• Engine power. 1.8 liters. с.;
• Engine displacement is 33 cm3 ;
• Fuel mixture tank capacity of 575 ml.;
• Chain lubrication tank capacity. 350 ml.;
• Working bar length. 35 cm.

This Homelite chainsaw comes standard with a standard chain and bar. Kit also includes oil for chain lubrication, maintenance tools, and a protective cover for the tire.

Other features include a lightweight ZipStart system, which makes the starting jerk of the cable sharper and more stable. Thanks to the electronic ignition system, the tool starts with just half a turn of the starter, which is already appreciated by professional woodcutters and owners of small garden plots.

Model range

The range of chainsaws Homlite includes:

CSP-4016

This tool is used for making firewood, building log cabins, and as a lopper.

Easy to start, easy to build and easy to operate. Increased diameter of teeth results in higher levels of safety when working. End of chain saw features Safe T-Tip guard to protect you from injury from kickback.

Handles are equipped with anti-vibration coating, which helps reduce stress on the hands while cutting.

Chainsaw is equipped with a two-stroke engine, body is made with impact resistant plastic.

Homelite CSP-4016 chainsaw specifications:

Tool fuel tank capacity	0,6 л
Maximum engine power	2,5 л. с.
Chain pitch	0.325 in
Working volume of the power unit	40.2 cm³
Working tire length	400 mm
Total weight	4.5 kg
Capacious oil tank	0,35 л
Groove diameter	1.3 mm
Engine rpm at idle speed	2600 rpm
Number of links	72
Overall parameters	Length. 485 mm Width. 300 mm

CSP-4518

This version has a two-stroke power unit with a carburetor, an engine brake, which is necessary for emergency shutdown of the tool in case of a strong kickback or when the user’s hand contacts the safety guard.

The tool starts up thanks to an electronic ignition system. The model is distinguished by the increased service life of all components and assemblies, as well as by the use of a powerful engine, due to which the equipment can saw timber with a diameter of up to 400 mm.

Inside there is a system of automatic lubrication of internal units and parts, a mechanism that reduces the level of vibration during operation. Filter element inside for long life.

Performance characteristics of the tool Homelite CSP-4518:

Saw bar length	450 mm
Power Unit Power	2,5 л. с.
Chain pitch	0.325 inch
Engine displacement	45 cm³
Fuel capacity tank	0,575 л
Oil tank capacity	0,35 л
Total weight	4.4 kg
Permissible noise level	104 dB
RPM at idle speed	Minimum. 3400 rpm Maximum. 12500 rpm
Groove diameter	1.2 mm
Number of links	72
Number of speeds	1

CSP-3314

The design features of this modification include: a compact engine with low fuel consumption and electronic ignition system and easy starting. Inertia-controlled emergency stop mechanism for safe operation.

Higher productivity levels due to large fuel and oil tank and anti-vibration mechanism, designed to reduce operator fatigue.

For user comfort there are rubberized handles and throttle damper.

Homelite CSP-3314 chainsaw specifications and features:

Motor power	1,8 л. с.
Chain pitch	0.325 inch
Maximum length of working bar	350 mm
Engine displacement	33 cm³
Gross weight	4,3 kg
Slot	1.1 mm
chain thickness	1.27 mm
Gasoline tank capacity	0,575 л
Oil tank capacity	0,35 л
Number of teeth on one wheel	6
Highest engine rpm at idle speed	12500 rpm
Permissible noise level	112 dB

In order to start the power unit of the tool, you need to press the special button, which is located on the right side on the body of the saw. Ignition without stalling.

This chainsaw is equipped with anti-vibration handle guards, an accidental start mechanism, a primer, a metal stop to secure the tool to the working surface, and an upgraded airflow system.

Technical indicators and data of this modification:

Tool fuel tank capacity	0,575 л
Maximum engine power	2,5 л. с.
Chain step	0.325 in
Power train displacement	0,45 л
Working bar length	450 mm
GVW	4.4 kg
Oil tank capacity	0,35 л
Number of links	72

Technical and performance features

Saws body is made with impact-resistant and durable plastic to reduce weight to 4.7 kg. Saw is equipped with 40.2 cm3 two-stroke engine, which at maximum 12500 rpm produces 2.58 L.с.

Working mixture enters carburetor from 0.37 L gasoline tank. The Homelite CSP 4016 power package offers stable idle and vibration speeds, generous torque reserves and economical use of fuel and lubricants.

Model	Homelite CSP 4016
Manufacturer	Homelite
Production (assembly)	China
Brand Country	USA
Saws class	Household
Power, l.с. (kW)	2,58 (1,9)
Engine displacement, cm3	40,2
Engine type	2-stroke, gasoline
Tire length, cm (inches)	40 (16)
Number of links	66
Chain pitch	0,325
Chain thickness, mm	1,3
Fuel tank capacity, l	0,37
Oil tank volume, l	0,24
Warranty, years	1
Weight, kg	4,7

Model range: technical and performance features

Homelite CSP 3314

The range of applications of this model weighing 4.5 kg includes. sawing fuel wood, cropping trees, not excluded the use of a light and compact tool in wooden construction. Power of the 2-hp engine is enough to activate the 14″ saw headset.

Despite the small 33cc engine displacement, the Homelite chainsaw is equipped:

• easy-starting systems;
• electronic ignition;
• air cleaner and vibration compensator;
• autonomy of operation improved due to enlarged fuel tank capacity to 570 ml.

Homelite CSP 3316

Performance capabilities of identical traction class chainsaw have been expanded by installing a more productive 40cm long bar, increasing the effectiveness of the standard vibration damper.

The reliability of the automatic lubrication and cooling system of the saw head and the resistance of the plastic parts to unfavorable external influences were improved in this model.

The use of an oil pump with adjustable capacity provides 50% savings in chain oil consumption and helps users to avoid the use of cheap and inefficient oil and lubricant substitutes.

Homelite CSP 4016

When designing this model, emphasis was placed on improving the safety of demanding sawing jobs, optimizing traction parameters of the engine. The functionality of this tool is enhanced by the use of a 1.5 kW engine, a special smooth running chain attachment, a nose-mounted Safe-Tip guide bar cover.

This enhancement facilitates proper start of sawing, virtually eliminates risk of injury from kickback. The 4016 can be operated with 41- to 50-cm-long tires.

Homelite CSP 4518

Many features of the 3-horsepower 45 cc engine qualify it for semi-professional status.

The Homelite chainsaw of this series differs from previous models:

• The use of handles with perfect vibration protection;
• The presence of a three-stage air cleaner;
• Tool-free access to internal components;
• manual and inertia activation of the emergency brake;
• metal chain catcher.

The advantages of this model are high torque reserve, economical fuel consumption, and the ability to work long hours without frequent stops to cool the power train.

This series of chainsaws is designed to mechanize complex and high volume of work associated with felling trees, sawing wood for firewood, cleaning selected for the construction of sites from high-growth shrubs.

Homelite CSP 4518 chainsaw. features and capabilities

This Homelite model comes standard with a proprietary 2-stroke gasoline motor with increased torque. Engine is equipped with forced air and manual starter with decompression system.

The Homelight 4518 chain saw is equipped with an effective inertia chain brake. A long-life oil pump is responsible for the lubrication of the saw unit and is only activated when the chain is running on the bar.

All of the model’s internal parts and mechanisms are housed in a rugged housing. It is made of multi-layer plastic reinforced with metal elements. This gives the chainsaw the ability to withstand hard knocks on foreign objects and falls from heights up to 2 meters.

The manufacturer has provided easy access to the air filter and other frequently replaced parts of the saw. This makes it possible to install new parts without disassembling the entire tool.

Features of this Homelight model include:

• Standard engine power. 3 liters. с.;
• Fuel tank capacity. 570 ml;
• the possible length of the bar used for work. 40-45 cm;
• The pitch of the regular chain is 0.325 “;
• weight with headset: 4.6 kg.

The Homelight 4518 features a low weight and relatively modest size. This makes it possible to use the tool to work at height and in hard-to-reach places.

design features

Despite possible differences in design, chainsaw carburetors work on the same principle, so the adjustment sequence of different models does not differ significantly.

Most high-end chainsaws from leading manufacturers have technically advanced carburetors with in-built compensators and automatic choke control. Such modifications contribute to the operator’s comfort, but do not affect the fuel economy and other operating parameters.

The list of accessories includes a priming pump to enrich the mixture before starting the power unit. Many professional chainsaw models are equipped with a carburetor heater that turns on when the tool is switched to winter operation.

Preparing for self-adjustment of fuel equipment

Instructions for adjusting the carburetor are provided in the operator’s manual. The factory kit includes a screwdriver to adjust the screws labeled L, H, and T. Some manufacturers add a carburetor to their chainsaws that requires a special adjustment wrench.

A proper fuel system setting calls for warming up the power package to operating temperature and pre-cleaning the air intake filter. The saw is set in a position that allows easy access to the fuel system.

To summarize

If you think about it, the adjustment of the carburetor. an extremely simple occupation. The main thing is to follow certain rules. But if it is not done in time, it can cause serious problems up to overheating of the engine that will lead to its jamming. The result is predictable. a trip to the store and unforeseen financial expenditures. This is especially true for more expensive models. On the other hand, you should not run to a service center with a chainsaw when you have the first suspicion that it is time for a tune-up. And so, the adjustment of the carburetor of a chainsaw with their own hands is the best option in such a situation.

We hope that the above mentioned information will help some of the readers to keep their usual tools in good working order for many years. After reading this you might have some questions or the explanations are not very clear. If so, write about it in the discussions below. Homius will be happy to explain what you do not understand. There you can also leave a comment on the article, express your opinion about it or share your personal experience in adjusting a chainsaw carburetor, if any. And please don’t forget to evaluate what you read, it’s very important for us.

Finally, by a long-established tradition, we offer you a short video that will help to more fully disclose today’s topic, telling about the carburetors of Chinese chainsaws.

How to adjust your chainsaw carburetor without a tachometer

These units require a tachometer setting. If you carburettor misfire on machines without a tachometer, it can quickly lead to malfunctions. However, it is also possible to tune the saw in the absence of a measuring device. Let’s look at the step-by-step instructions for chain saw tuning.

Screwing and unscrewing

The adjusting elements of the chainsaw carburettor have different classifications. They can be adjusted with a normal screwdriver. There are three such elements in total:

• Screw H. Required to adjust the maximum RPM of the equipment;
• screw T. is responsible for the idle speed setting;
• L screw. Adjusts the chain saw’s low RPM.

Tweaking each screw changes the settings. First you need to tighten the screws H and L until they are fully seated, but not too much, and then gently unscrew two turns, no more. Screw T is screwed all the way in without loosening.

Starting chainsaw

After the initial settings have been made, the equipment should be started. Then loosen the idle speed screw together with the throttle trigger to get the saw more stable. In case of low idle speed, tighten the screw T.

Acceleration test

When the speed of the equipment is increased, the stroke must not fall off. If there is a malfunction on this point, you need to adjust the low rpm by tightening the L screw.

Moment of RPM drop

The last step is to fix the torque drop. This can be done by adjusting the H. But it is very important to watch its twist. you must not overdo it

To do this you need to press the throttle to the maximum and twist this element. Then you need to catch the moment of overfueling and a drop in RPM to start turning the propeller harder. This allows you to properly adjust the saw without a tachometer for torque. Once they have been adjusted, the chainsaw can be operated.

Effectiveness of the method

This way of adjustment is effective for machines without tachometers. But it will only work effectively under the following conditions:

• The fuel filter is free from mechanical damage and dirt;
• The exhaust system is not clogged with fouling and allows you to gain high revolutions;
• the ignition system is fully functional: the spark plug and ignition module provide stable operation;
• all fasteners are in place and screwed all the way in before starting the adjustment procedure so that you can start to adjust them in the same positions afterwards.

If it was possible to carry out the adjustment of the equipment without a device that measures the speed of the carburetor, then you do not need to do anything else. It is only worthwhile to periodically tighten the screws in case they become loose.

To adjust the carburetor of a chainsaw, it is not necessary to have a tachometer handy. With the help of regulating elements, you can adjust the work of this device for a long time without going to the service. The main thing is to know how many turns to turn the screws, and in what order to do it. Then your chain saw will not need adjustment for a long time.

Step-by-step instructions for disassembly

The device of the carburetor of models of different brands is almost the same, so let’s take a chainsaw Partner for example. Each element is carefully removed and put in order, so that then it would be easier to assemble.

The difference, if any, in the carburetors made by different manufacturers is not crucial

The upper cover can be removed by unscrewing the three bolts. Followed by foam rubber, part of the air filter.

The arrows indicate the bolts that must be unscrewed to remove the cover

Then we remove the fuel hose, followed by the actuator rod.

The upper arrow points to the fuel hose and the lower arrow to the actuator rod

Next, it is necessary to remove the tip of the cable.

The arrow shows the cable end that needs to be removed

On the left side of the pipe pull the gas hose.

Remove the gasoline hose pointed by the arrow

Completely disconnect the carburettor and it is ready for adjustment. Its mechanism is quite complex, so if you want further disassembly of the carburetor, you should remove the elements very carefully. they are small, so they can get lost.

The carburetor consists of many small parts, which should be dismantled in order

Features of tuning and adjustment

To learn how to adjust the carburetor on a chainsaw, you must learn to distinguish between three screws (some models have only one).

L and H screws are only superficially similar; in fact, they are different

Each screw has its own letter designation:

• The “L” is for adjusting the low RPM;
• The “H” screw is used for the upper adjustment of the rotational speed;
• “T” is needed to adjust the idle speed (models with only one screw have it only).

The factory adjustment is optimal, and with the help of screws adjust the operation of the engine in special situations (work associated with different climatic conditions).

Diagram shows carburetor adjustment screws outputs with cover closed

To adjust the chainsaw use a special tool

They are only to be adjusted with the L and H screws. To increase the RPM, they are turned clockwise. To lower it, turn counterclockwise. Sequence of use of screws: L. H. T.

If there are any doubts about the adjustment, it is better to contact an expert, because a wrong adjustment can put the engine out of operation.