Why the crankshaft bends on a Chinese chainsaw

Popular malfunctions and chainsaw repair with their own hands

A chainsaw. a worthy replacement for hand saws and axes. Today this tool is available in almost every household. it is indispensable for the arrangement of the garden plot, construction and repair work. Intensive use and improper care for the tool can lead to its premature failure. However, the owner of a chainsaw does not have to go straight to the workshop. many of the malfunctions that can happen to it during operation, it is quite realistic to eliminate on their own.

• 2 Starting the engine: Checking the spark plugs
• 3 Do-it-yourself chainsaw repair: the fuel system
• 4 Troubleshooting muffler problems
• 5 Repair of the cylinder-piston group (CPG)
• 6 Checking the carburetor and tips for adjusting it
• 7 Calibration algorithm and safety precautions for troubleshooting chainsaw carburetor
• 8 Other chainsaw malfunctions
• 9 chain saw repair with your own hands, video

Chainsaw cuts sideways

You may see an uneven cut when sawing. Why the chain saw cuts crooked? There are several causes:

• Incorrect chain sharpening. Incorrectly angled or to one side only. Correct sharpening needed.
• Improperly selected timing chain. At very high RPMs, even a difference of 0.2-0.3 mm between the width of the groove or the width of the fit will be visible, why the chainsaw and saws sideways. Correct chain needs to be installed.
• Uneven bar wear. Over time the bar will wear on one side and the chain will slip to the side. Turn the tire regularly so that the wear is even on both sides. If the wear is too great, replace the tire.

Engine

In most cases, the following problems are found in the engine:

• the engine has stopped starting;
• the engine will start, but after a while it will stop;
• the engine is not able to develop the necessary power;
• The engine is running very erratically.

How to check the crankshaft oil seals

The presence of packing leaks can only be checked by getting to the crankshaft itself, and carefully examining it for leaks. You can find out how to do this correctly at

How to check compression on a chainsaw

If the compression level is below 8 atmospheres, the engine will not have enough power, and therefore the chainsaw will not be able to function fully.

• Remove the protective cap and unscrew the spark plug.
• Insert the tip of the compressometer into the hole where the spark plug should be.
• Use the starter cord to rotate the piston and note the maximum reading of the measuring device.

How to put the piston on the chainsaw correctly

Work on replacing the piston for most models of modern chainsaws is carried out according to the following algorithm:

• The top and side covers are removed.
• The spark plug is unscrewed.
• Stoppers are removed from shock absorbers and the handle is detached from the body.
• The drive sprocket and starter motor are removed.
• Piston stopper is installed in the spark plug hole and the nut fixing the flywheel and clutch is unscrewed.
• Detach the flywheel, clutch, and oil pump worm gear, located immediately behind the clutch.
• The screws that secure the carburetor and air filter are loosened and the assemblies are removed along with the engine control lever.
• The ignition coil is removed, as well as the muffler.
• The saw is turned over with the base plate upside down, the engine is detached by loosening the screws that fix it to the body.
• Unscrew the pallet and remove the piston.
• Since the piston can only be removed together with the crankshaft, you have to remove the circlips to loosen it.
• The old piston is replaced with a new one, but as carefully as possible. This is caused by the high brittleness of the compression rings.
• The crankcase is put back in place and a sealant is used in place of the gasket.

All further actions are performed according to the algorithm, the reverse of disassembly.

Purpose and principle of operation

The ignition coil allows the low voltage electrical impulse from the current source to be converted into a high voltage impulse, without which no spark can be produced. It can have from 1 to 3 lobes in the electrical breakdown gate. Depending on the specifications of the power plant, the breakdown gap may be between 0.4 and 1.1 mm. To ensure reliable ignition, the voltage of the electrical impulse must be at least 10 kV. Remember the possible voltage drop in the conductors and therefore the coil must produce a pulse of 12-20 kV.

Such voltages can pose serious danger to persons, especially those suffering from various heart problems. When checking a faulty coil, you must exercise the utmost caution, because even standard rubber gloves can not guarantee complete safety. The operation of this element resembles an autotransformer. Copper wire coated with insulating varnish is used to create the primary winding. Most often the number of turns is 100-200. The secondary winding has a thinner conductor, but has 2000-3000 turns.

During the operation of the power plant, a cam mechanism located in the tumbler rotates. The main task of this element is to open the contacts. When a short circuit occurs, a high current is passed through the primary winding. This induces an induction in the secondary coil and a high-voltage impulse is transmitted to the spark plug gap.

This ignition circuit has been used in cars for a long time. Its main disadvantage can be considered the burning of the contacts due to the high current flowing through them. Often the owners of vehicles supplemented the factory circuit with a simple electronic amplifier.

Today the situation has changed, and manufacturers are actively using more reliable devices, such as a Hall sensor, instead of breakers. If the user needs to know how to check the ignition coil of a chainsaw with a multimeter, this procedure is carried out similarly to that for testing car plugs.

Checking the chainsaw‘s major systems

If the chainsaw refuses to work properly, you need to make sure that all the conditions necessary for its normal operation are met:

Then you need to consistently check the work of all its elements. First you need to check the fuel tank. If the cause is not the volume or quality of the fuel, the likely causes of the malfunction could be the spark plugs. The gap in the plugs should not exceed 0.5 millimeters. If it is too small, it means that soot has settled on the candles. In this case, remove the spark plugs, clean them, then reinstall them and try to start the chainsaw. In addition, from time to time, it is recommended to replace the spark plugs completely with new ones, even if they are in good condition.

Then check the condition of the fuel filter and carburetor. Cleaning the fuel filter yourself. A simple task, but it is better to leave the repair of the carburetor to the professionals.

The chain saw starts and shuts down. the cause

If the chainsaw starts and goes out on the first try, the chain brake may be the cause, or the chain may be jammed due to lack of oil. In this case the oil level should be measured. If the amount of oil is sufficient, the cause may be the tube that leads it to the lubrication mechanism.

Another reason could be carburetor malfunction. If it only needs adjustment, you can do it yourself according to the instructions. If the carburetor needs to be cleaned or repaired, you can’t do without professional help.

Low fuel level in the fuel tank is another possible cause. In this case, the chainsaw stalls when it is tilted because the rest of the fuel mixture is in the part of the tank that is opposite the suction tube.

The chain saw starts and shuts down. the cause

If the chainsaw starts and stops on the first try it may be because the chain brake is giving out or it is jammed by lack of oil. In this case, the oil level is measured. If the amount of oil is sufficient, the cause may be the tube that leads it to the lubrication mechanism.

Another reason could be a carburetor failure. If it just needs adjusting, you can do it yourself according to the instructions. If the carburetor needs to be cleaned or repaired, you can not do without the help of professionals.

Another possible cause of this malfunction is a low fuel level in the tank. In that case the chainsaw stalls when you tilt it because the rest of the fuel is in the part of the tank that is in front of the suction tube.

Assessment of condition of a cylinder-piston group

It is not uncommon for the engine not to start or not to run at full power due to low pressure in the cylinder. It can be caused by wear of the piston or cylinder, retracted piston rings, worn bearings. To partially discern the state of the cylinder-piston group (CPG) is possible by removing the muffler and peeking through the opening.

Compressometer placed in the plug hole, will help to make a compression test in the engine. the measurement results can also gloss on the state of the cylinder and piston rod. Clean data is only available after the mechanism has been fully disassembled. If there are chips or scratches on the piston, it must be replaced. The piston ring must be unstained, free of carbon deposits, and must be exactly in its proper place.

Piston and crankcase wear is a severe problem

The results of compression measurement can be used to judge the condition of the parts of the cylinder head

Checking the ignition system

The first thing to do when the chainsaw is broken is to inspect the spark plug by disconnecting the wire and carefully unscrewing it with a special wrench.

Parts of the ignition system: 1. handwheel with magnets, 2. ignition module, 3. spark plug, 4. high voltage cable

Spark plug is unscrewed to check its condition

• Dry. Most likely no fuel mixture is getting into the cylinder. It’s not the ignition system, so the spark plug is screwed back in.
• Highly splashed with fuel. Excessive fuel mixture is caused by either improper starting or improper carburetor adjustment. Wipe the spark plug thoroughly, turn off the fuel and turn on the starter to remove the excess fuel and air in the combustion chamber. Then the spark plug is put back in place and the mechanism is started again.
• Black fouling. This could be an indication that poor quality oil has been used, that the carburetor is not properly adjusted, or that the gasoline to oil ratio is incorrect. The spark plug should be washed and cleaned of carbon deposits with a sharp object (an awl or a needle), wiped with an emery cloth and repositioned.

Checking the spark plug, you need to pay attention to the gap between the electrodes: the normal range is from 0.5 to 0.65 mm. Damaged or worn gasket should be replaced.

A large amount of black sludge on the spark plug indicates a malfunction of the engine

To be sure, check also the spark. To do this, the ignition cable is put on the spark plug, connect the nut with pliers and the cylinder, start the starter and watch for sparks. If it is missing. the spark plug must be replaced. If a new spark plug also doesn’t produce a spark. the problem is in the high-voltage wire or in a violation of the connection with the spark plug.

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Preventive maintenance

Improper care and use of the tool contributes to shortening its service life. To extend its service life before the next repair, it is necessary to follow some preventive recommendations.

• Before each start-up, check that the chain is in good condition, tensioned and the teeth are properly sharpened.
• During sawing give your tool a rest from time to time, especially if it is a domestic or semi-professional chainsaw.
• Clean the chain, bar, air filter, housing and other slots and grooves where sawdust may have entered after completing work.
• Turn the tire periodically to ensure even wear.
• Use only quality oils and fuels.
• Do not store fuel mixture for a long time, so drain residue from the tool and dispose of it.

Work should not be done until you are sure everything is in order. These simple preventive procedures can significantly extend the life of the tool.

Signs of machine malfunction

Chainsaw malfunctions have certain signs. Engine problems are manifested by an inability to start, stalling after a short run, unstable operation, overheating, smokiness, loss of power during operation. All other signs may mean other saw systems are broken.

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Chainsaw repair with your own hands: the fuel system

If the fuel mixture is not flowing into the cylinder, but the spark plug is working fine, it could mean that:

To clean this unit, you should remove the fuel hose and check the jet. If it is weak, the filter should be taken out through the fuel tank filler port and cleaned or replaced if it is completely worn out.

Replace the fuel filter at least every 3 months as a preventive measure.

It is nothing but a hole in the fuel tank lid, which can be cleaned with an awl.

There may be several reasons:

• the air filter is clogged (in this case it must be removed, washed with water, dried and put back);
• The carburetor settings are out of tune (this unit should be re-adjusted);
• The integrity of the carburetor membrane has been compromised (must be replaced);
• the carburetor channels are clogged (it is necessary to disassemble and clean all parts and assemblies).

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Engine

In most cases the following problems are found in engine operation:

• the engine has stopped starting;
• the engine starts, but stops after a while;
• The engine is not able to develop the necessary power;
• engine becomes extremely unstable.

how to check the crankshaft oil seals

The oil seals are leaking which can only be checked by getting to the crankshaft itself and carefully inspecting it for leaks. On how to do it correctly, you can read on

How to check compression on a chainsaw

At a compression level below 8 atmospheres the engine will not have enough power, and therefore the chainsaw will not be able to operate normally.

• Remove the protective cap and unscrew the spark plug.
• Insert the tip of the compressometer in the hole where the spark plug should be.
• Use the starter cord to rotate the piston and memorize the maximum reading of the measuring instrument.

How to put the piston on the chainsaw correctly

Work on replacing the piston for most models of modern chainsaws is carried out according to the following algorithm:

• The top and side covers are removed.
• Unscrew the plug.
• Remove the locks from the shock absorbers and detach the handle from the housing.
• Driving sprocket and starter must be removed.
• A piston stopper is installed in the spark plug hole and the nut securing the flywheel and clutch is unscrewed.
• Remove flywheel, clutch, oil pump worm drive, located just behind the clutch mechanism.
• The carburetor and air filter screws are unscrewed and the assemblies are removed along with the motor control lever.
• Take off ignition coil and exhaust silencer.
• Turn the saw upside down and detach the engine by removing the screws that fasten it to the housing.
• Unscrew the crankcase and take out the piston.
• Since the piston can only be removed together with the crankshaft, to undo the piston you must remove the retaining rings.
• The old piston is replaced with a new one, but as carefully as possible. This is caused by the high brittleness of the compression rings.
• Crankcase is reinstalled, and sealant is used instead of gasket.

All steps that follow are done in reverse order of disassembly.

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How to disassemble the chainsaw: step by step process with photo and video

Complete coverage of the design of a multi-faceted mechanism based on the operation of a two-stroke internal combustion engine. From the air filter cover, to the crankcase oil seals. Here’s an example of a complete, step-by-step disassembly of a chainsaw system. To be informative and concise, the purpose of each part is described in a nutshell. The following photo and video instructions will show you how to fasten each part with the subtleties of the different models.

The technical complexity of any mechanism can be measured relatively accurately by the number of parts interacting in it. Efficiency of repair and maintenance of the tool, depends on understanding the task of each element, but to follow a step-by-step instruction, knowledge of individual terms is quite enough. In the following list, supplemented with a picture, it is popularly shown, what the chainsaw consists of, with the description of the main parts in one short phrase (where it is necessary).

• The fuel tank casing is the base for mounting the mechanism and controls.
• Damper muffler.
• Special screw. shock absorber retainer.
• Rubber shock absorber. 1 of 4 that are installed.
• Throttle trigger is a carburetor throttle control element.
• Gas pedal rod. the curved bar that connects the carburetor to the trigger.
• Air valve. supplies air to the tank when the fuel volume decreases.
• Fuel filter.
• Fuel tank hose. conveys fuel from the tank to the carburetor.
• Air filter cover.
• Air filter. protects carburetor from dirt.
• Cylinder cover.
• Lever. adjusts carburetor choke position.
• Carburetor. a device for metering air-fuel mixture into the combustion chamber.
• Insulator. effective sealing gasket between carburetor and engine.
• Carburetor elbow. connecting component.
• Spark plug. provides the spark into the combustion chamber.
• Cylinder. main part of the engine casing.
• Silencer. reduces noise, dampens sparks and directs exhaust gases away from the operator.
• Ignition coil (magneto). generates an electrical impulse transmitted to the spark plug.
• Ignition switch. closes and opens contacts on coil.
• Knob.
• Flywheel. balances the clutch, pre-clears the air, and generates a charge in the coil.
• Bearing. secures the crankshaft to the crankcase.
• Crankcase left. part of the base to hold the engine and moving parts.
• Piston.
• Piston shaft. connecting the piston to the crankshaft.
• Crankshaft. converts reciprocating motion of the piston into rotation.
• Oil suction hose. connecting oil reservoir to pump.
• Right crankcase housing.
• Oil pump. pumps oil from the reservoir to the chain as the sprocket rotates.
• Clutch drum. first element of chain contact.
• Clutch. transmits rotation to the drum at higher rpm.
• Chain brake knob.
• Tire cover. hides clutch and oil pump (includes tensioning mechanism).
• Chain catcher-wraps or engages the chain if it breaks.
• The starter is the mechanism for manually turning the crankshaft, to create a spark and start the engine.

The components shown above give a complete picture of the construction of a typical chainsaw. Most parts, consisting of several smaller parts, but disassemble them individually only when repairing a specific assembly. To get to the engine, elements can be removed in groups without disassembling the tire cover or the starter by the screws. If you want to get a better idea of the chain saw’s components, or to learn about all the components of a particular part, with the full version of the list.

Disassembling a Chinese chainsaw

Detailed photo instruction on how to fully and consistently disassemble all parts of the mechanism. On the example of Chinese chainsaw we can see how all components interact. Disassembly performed on a clean drive unit, without the bar, chain, gasoline, and oil.

For easier manipulation of the object and easy access to the parts, first remove the handle, unscrewing the tire cover in advance.

Having cleared the room for maneuvers, we can move on to the main components. Remove the upper cover, the air filter and the spark plug.

Remove fixing screws and take off the cylinder head.

Remove the carburetor, for which we disconnect the lever of the air damper, unscrew 2 fixing screws and take out the base of the air filter. Disconnect throttle trigger and exhaust pipes.

Remove the throttle lever so that it does not interfere with further disassembly. To do this, take off the top cover of the handle, disconnect the rod from the trigger and pull it out through the hole.

Remove the starter motor cover by removing the four screws.

We proceed to disconnect the housing from the crankcase, removing the chain catcher and shock absorbers.

Disassembly of the engine begins with the removal of the carburetor elbow ring, gasket and insulator. For convenience, it is better to use narrow pliers.

Unscrew the retaining nuts/screws and remove the muffler. Remove the gasket and studs.

Now, removing the engine cylinder comes down to simply unscrewing the 4 screws. You will need a screwdriver or bit with a long rod.

To detach the piston from the crankshaft, remove the circlip and remove the shaft.

The ignition module is secured with a couple of screws and is removed in a few rotations of the screwdriver.

Clutch is unscrewed clockwise and rotates with the crankshaft which should be locked by placing the axle against the handle of the pliers. An angle grinder wrench or a hammer and chisel can be used, but a special puller is better.

In fact, the clutch and flywheel are easier to unscrew before removing the cylinder and piston, which is easier to fix by placing a piece of thick rope or cable in the spark plug hole.

Following the clutch, remove the sprocket drum, needle bearing and worm gear.

Unscrew the side plate of the crankcase and the oil pump cover and remove the oil pump.

Pull out the pipe that connects the pump to the oil reservoir.

Fix the crankshaft and unscrew the flywheel (counterclockwise).

Unscrew the cover and unscrew the oil seal.

It remains to unscrew all the screws fixing the crankcase and separate the halves (force will be required).

Remove the bearings from the crankcase, you can do it by knocking. To install closely back, the place should be heated with a construction hair dryer.

Chainsaw carburetor adjustments and chinese tool construction

The carburetor in internal combustion engines is responsible for preparing the fuel mixture. It consists of gasoline, air, and oil. When all these ingredients have been used in the wrong proportions. the engine will not run smoothly. To prevent this and need to adjust the carburetor chainsaw.

How the carburetor works

Regardless of the chainsaw manufacturer, the order and principles of carburetor operation remain the same. This device consists of several basic elements:

The air passes under atmospheric pressure into the narrower part of the pipe where the airflow is regulated by the slider. Also here the air becomes discharged and the resulting vacuum draws the fuel from the fuel line. A special needle connected to the jug chamber is used to adjust the fuel flow rate. The quality of the fuel mixture is regulated by the choke. when the air is opened, more fuel begins to flow into the carburetor and the power of the propulsion system increases.

To avoid problems with the operation of the tool, it is necessary to periodically adjust the chainsaw. When too much air enters the mixture, it becomes depleted and engine power is reduced. A lack of air also negatively affects the unit’s performance, as fuel consumption increases. It does not burn completely, resulting in fouling on the cylinder walls. It is quite obvious that the question of how to adjust the carburetor on a chainsaw is asked by many owners of this tool.

First, however, it is worth noting the signs of a quality power unit:

• RPMs pick up quickly.
• The engine sounds like a four-stroke engine.
• At idle speed there is no cranking of the chain.

Situations in which adjustment is necessary

The new tool is already prepped and ready to go. In this regard, for some time the question of how to adjust the carburetor on the chainsaw, will not arise. However, experienced owners of the unit often make fine adjustments. To do this, there is absolutely no need to disassemble the carburetor, as its design provides for three adjustment screws:

• L. used at low rpm.
• H. allows you to adjust the maximum flow of combustible fluid.
• T. necessary for adjustment at idle speed.

All fine tuning is done by ear, and at this time the safety rules must be adhered to. Before starting all the manipulation, the adjusting screws should be labeled so that it is easier to return to the default setting if necessary.

The most frequent problems are the adjustments that are performed after the machine malfunctions. Among the main reasons for their appearance should be noted:

• Screws unbalanced and protective cap misaligned.
• Wear of the piston system, which requires changes in the fuel mixture.
• Problems with the carburetor itself.

Algorithm of adjustment

All carburetor chainsaw tune-up work is done in four steps:

Adjustment of the engine is performed for its uninterrupted operation at low revolutions.
• The carburetor is tuned to create and deliver a quality fuel mixture.
• Fine adjustment is carried out at idle and only after the power unit has warmed up.
• Check the quality of the tool in all modes.

And now for more details on how to fine tune the chain saw. If the tool does not start, the screws H and L must be returned to their initial positions. Then start the engine and let it warm up. After that you can start to adjust at a low rpm. The L and T screws are to be used to achieve the optimum operating point.

The first thing to do with the L screw is to start the engine at maximum rpm and then release it at ¼. The T-Screw is used to adjust the idling speed of the propulsion system. The traction and the maximum rpm adjustment is done with the screw H which should be turned slowly while looking at the electronic tachometer. It is important to remember not to exceed the tool manufacturer’s maximum RPM.

After the adjustment, you need to let the engine cool down. Then it only needs to be started according to the cold start algorithm. If there are no problems at this time and the chainsaw is running fine when idling, you should check it under load. If a lack of power of the power unit is detected, the adjustment is carried out with the H screw.

Almost all Chinese chainsaws are equipped with carburetors, the construction of which is similar to the European models. The differences in the settings will therefore be minor. for the initial adjustment, the H and L screws need to be turned two turns. All the following steps remain unchanged.

The device of a chainsaw and tool repair with their own hands

The chainsaw is a valuable helper in the household today. For many owners of country houses, this unit has become indispensable. Despite its relatively simple construction, the tool sometimes breaks down. However, to make the repair of a chainsaw independently can almost any person who has a certain baggage of knowledge in the field of technology and has a set of necessary tools.

Design of chainsaws

The uncomplicated design of the tool allows you to carry out the repair of a chainsaw with your own hands. The main elements of the unit are as follows:

Depending on the brand, there may be some changes in the design of a particular tool. For example, the engine can be located horizontally or vertically. In professional saws the second option is most often used. Thanks to the horizontal positioning of the power unit, the size of the tool is significantly reduced, which is important for home use. Knowing the device of the unit, you can quickly understand how to disassemble the chainsaw.

The most frequent defects of the tool

No matter how well your machine is used, it occasionally malfunctions. To fix them, you need to determine the cause. Knowing the structure of the chainsaw, we can say that the most frequent problems arise with the operation of the engine. But do not forget about the other components, which are also subject to wear and tear.

Powertrain malfunctions

It can take quite a long time to identify the cause of the malfunction in the work of the engine. Among the main signs of breakdown are several major ones:

• The engine does not start.
• The power unit starts to work, but quickly stalls.
• The maximum power is not obtained at idle speed.
• A malfunction is noticed.

When diagnosing a malfunction, it is necessary to use the method of exceptions. It is better to start checking causes which will take the least time to eliminate. Most often the fault of the power unit is related to the ignition system. It is the condition of the spark plug that can tell a lot about the performance of the entire engine. First it is necessary to remove this element with a special key and then check its external condition. The operation of the ignition system can be easily determined by the formation of sparks. When a strong and steady spark appears, proceed to inspect the fuel system.

There may be the following problems in its operation:

• A clogged breather cap is preventing the flow of fuel.
• The fuel filter is clogged.
• Not enough fuel is getting from the carburetor to the cylinder.

To correct the problem, the system should be disassembled and thoroughly cleaned. Fuel problems may be caused by a clogged filter that prevents the proper fuel mixture from being created. If the chainsaw stalls under load, check the muffler, which may have accumulated a large amount of combustion products. The most difficult problem is a failure of the cylinder-piston group. This applies not only to the repair of the Chinese chainsaw, but also products of famous brands. In such a situation it is almost impossible to do without the purchase of spare parts.

Lubrication system and chain brake

When using the appliance, special care must be taken to check that the chain lubrication system is working. Most often, problems arise due to clogging of the channels through which the lubricant is supplied. If there is only a slight oil leak, you can carry on working with the chain saw. Otherwise urgent measures should be taken to remedy the fault.

The first thing to do is to check the tightness of the fittings to the tubes. It is quite possible that these parts have to be replaced, but a simple replacement of the sealant can do the job. Don’t forget about the oil pump, which must be checked visually. It must be replaced if there are cracks on the body. Problems with the operation of the brake are most often caused by contamination of the brake band.

How to use

Some rules should be followed to maximize tool life. This is especially true for the saw chain and guide bars. It is recommended that you change the chain every three hours, and turn the guide bar 180 degrees. This will cause even wear and tear on these elements, prolonging the life of the entire tool.

It is important to keep your chainsaw clean at all times during operation. Sawing wood can quickly become clogged with sawdust. that need to be removed in time. Dirty orifices can cause problems with the fuel system. It is also important to change oil and other consumables on time.