Chinese powertrains Lifan They are well-deservedly popular among owners of motorblocks, generators and mini tractors due to their reliability and availability. petrol-engine It takes a lot of attention over time, especially when it comes to fuel supply, and the carburetor's malfunction is not just about fuel overruns, it's about the risk of the piston group failing because it's running on a mixture that's too poor.
Symptoms requiring intervention are usually obvious: the engine stalls at idle speeds, sneezes into a muffler or carburetor, and black smoke from the exhaust pipe is observed. Owners often try to solve the problem by simply replacing candles or filters, forgetting that the engine is not a good fit. carburetor It's the heart of the mixing system, and it needs fine-tuning, and it allows you to get back to the factory and to keep the machine stable.
In this article, we will discuss in detail the process of setting up carburetors installed on popular models. Lifan The 168F, 170F and 177F series teach you how to set the fuel level, adjust the mix quality and achieve smooth engine performance under load. A competent service approach will extend the life of your equipment by hundreds of hours.
Diagnosis and preparation for setting up
Before you take on the screwdriver, you need to make sure that the problem lies in the settings of the carburetor, and not in mechanical damage or blockages. Diagnostics It starts with a visual inspection, check the air filter, the spark plug condition, and the intake manifold tightness, and pumping the extraneous air through the gasket can negate all adjustment efforts.
If the exterior elements are working, pay attention to the color of the soda on the candle. Black velvety soda indicates a rich mixture, and the white or light gray color of the insulator indicates a poor mixture, which is dangerous for overheating. Lifan engine It is sensitive to fuel quality, so before starting work it is advisable to drain old gasoline and pour fresh, with an octane number not lower than AI-92.
You will need a minimum set of tools to do the work: cross and flat screwdrivers, passages and clean rags. It is important to ensure good lighting of the work area, since the adjusting screws are often located in hard-to-reach places. It is also recommended to have a tachometer under you, although experienced craftsmen often adjust the engine “by ear”.
- 🔧 Check the tightness of the intake tract and the absence of air suction.
- 🔧 Clean or replace the air filter as the dirty filter enriches the mixture.
- 🔧 Make sure the fuel tank is filled with fresh gasoline without water or dirt.
- 🔧 Warm up the engine to operating temperature before starting adjustment.
⚠️ Warning: Never adjust on a cold engine. The heat gaps and evaporation of the fuel during cold start distort the idling system, which will lead to incorrect settings.
After the pre-production, you can go straight to the setting, and remember that the carburetor is a mechanism, and sharp turns of the screws can disrupt the factory calibrations, and act smoothly, fixing every change in position of the adjustment elements.
Carburetor device and screw arrangement
Carburetors fitted to engines LifanThese are usually float-type devices with fixed jicler, and understanding the basic components will help avoid errors, and the key elements here are the float chamber, the main fuel jicler, the idling system and the throttle valve.
The carburetor body usually has two main adjusting screws. The first screw, often called a "quality" or "mixture" screw, regulates the amount of air entering the idle channel at low revs. The second screw, the "quantity" or "idle" screw, mechanically limits the position of the throttle, setting the minimum engine speeds.
In some versions, the quality screw can be closed with a plastic plug installed in the factory, this is done to prevent unskilled interference, if the plug interferes with access, it is carefully removed, but you need to do this carefully so as not to damage the thread or the screw itself. Fuel mixture It should be balanced across all work regimes.
Why is the quality screw often closed with a stub?
The Lifan carburetors are set up in a factory on a special stand using a gas analyzer, the stub is installed so that the user does not interfere with environmental parameters or violate the optimal air-to-gasoline ratio calculated by the engineers, and the removal of the plug is only necessary during deep reconfiguration or repair.
And there's also the float chamber level adjustment screw, which is at the bottom of the carburetor, which affects the amount of fuel available for spraying, and the wrong level can lead to either overflow and rich mixing, or fuel starvation under load.
Before you start adjusting with a marker or paint, mark the original position of the screws. This will allow you to quickly return to the factory settings if you disrupt the rhythm of the engine during the adjustment process.
Step-by-step instruction: idling adjustment
Idle adjustment is the basic step that begins to restore normal operation of the engine, the goal is to achieve stable speeds at which the engine does not stall when a sharp gas discharge or "growls" excessively loud. Idle turn For most Lifan models, they range from 1,200 to 1,500 rpm.
The process starts by twisting the mix quality screw to the end (without fanaticism to keep the threads from breaking), and then twisting it 1.5-2 turns. This gives an approximate starting point. Then the heated engine starts, and the number screw is set to minimally stable revs. After that, the quality screw looks for the position at which the engine speed will become maximum.
When the maximum speed is found, the screw reduces the number of them again to the minimum stable. This procedure (maximum speed of the screw quality -> reduction of the screw number) is repeated 2-3 times until the engine starts to work smoothly and respond to the gas handle without failures. Stable work It's the main indicator of success.
☑️ Algorithm of idling setting
If the engine continues to run unstablely, the problem may be clogging of the idling channels, which would require a complete disassembly and washing of the carburetor with a special cleaner, often accumulating resinous deposits from old gasoline in the channels, which interfere with the normal passage of air.
⚠️ Attention: When twisting the screw quality do not make excessive effort. the cone of the screw can rest on the saddle, and further rotation will damage the sealing surface, which will cause leakage and inability to adjust normally.
Quality adjustment of the fuel mixture
After setting the idle speeds, you need to make sure that the engine gets the right amount of fuel when opening the throttle. Composition It directly affects engine power and temperature. Too poor (lots of air) causes the piston to overheat and burn, too rich (lots of gasoline) - soot, soot and power loss.
To test the quality of the mixture, you can use the cut-off method. On a warm engine, smoothly open the throttle. If the engine reacts sluggishly, "chokes" or black smoke comes out of the silencer, the mixture is too rich. If the engine stalls sharply when the valve is opened, or if you hear claps in the carburetor, the mixture is too poor.
The adjustment is done by the quality screw, but already in dynamics. If the mixture is rich, the screw is twisted (close the fuel supply or increase the air supply, depending on the design), if the poor one is twisted, the optimal position is considered when the engine develops maximum power and gains speed smoothly without jerking.
It's important to consider the operating conditions. If you use a motor unit or a generator in the highlands, you'll have to deplete the mixture (twistle the quality screw), because the air density is lower there.
| A symptom. | Reason. | Action. | The result |
|---|---|---|---|
| Black smoke, stained on a candle | Rich mix | Twisting the quality screw | Reduced flow, net exhaust |
| Cotton in the carburetor | Poor mix. | Twisting the quality screw | Improved traction, stability |
| The engine is dead with gas. | Abrupt transition of the mixture | Check the accelerator pump/jicler | Smooth set of turns |
| Overheating of the engine | Too poor mixture | Enrich the mixture | Temperature normalization |
The ideal mixture ensures the combustion of gasoline without residue, which is visible by the brick-brown color of the nose of the spark plug after working under load.
Adjustment of the fuel level in the float chamber
The level of fuel in the float chamber is the foundation of the whole carburetor working properly. If the level is too high, the fuel will flow through the throughpass, enriching the mixture and making it difficult to start hot. If the level is low, the engine will experience fuel starvation at high revs.
To adjust the level, you need to flip the carburetor and measure the distance from the plane of the housing connector to the top of the float. Lifan This parameter is usually about 15-17 mm, but it is better to look for accurate data in the manual to a particular model.
If the tongue is bent more strongly (float higher), the fuel level in the chamber will be lower. If the tongue is bent (float lower), the fuel level will rise. Be careful: the float must walk freely without touching the walls of the chamber, and its shut-off needle must tightly interlace the fuel supply when raised.
A common problem is the loss of leakage of the shut-off needle or the float itself. If there is gasoline in the float, it sinks and constantly opens the valve, causing overflow. Check the float with a shaking near the ear - there should be no splash of fluid inside. Float chamber It should be dry and clean.
Typical malfunctions and ways to eliminate them
Even when properly adjusted, the engine may not work properly because of hidden defects. One of the common problems is the wear and tear of the throttle and its axis. Over time, the axis breaks the seat in the carburetor body, forming a gap through which excess air is sucked in, making it impossible to normal idle adjustment.
Another problem is the elasticity of rubber seals, cuffs and gaskets bluff and crack over time, breaking the tightness, visually they may look whole, but when you heat them up, they start to leak air. Use a Quick Start aerosol or WD-40, squirting around the joints of the carburetor on the engine running. If the speed changes, then there's a suction.
Clogging of the main fuel jelly is the reason why the engine runs on idles but stalls when loaded. Giclerus has a very small hole that is easily clogged with microscopic rust particles from the tank. Pulling in compressed air and washing the carburetor cleaner usually solves the problem.
- 🔍 Wear of the axis of the throttle valve leads to air sucking and the inability to adjust the XX.
- 🔍 Fossilization of rubber seals violates the tightness of the intake tract.
- 🔍 Clogging of jelly jelly jelly with dirt or water causes the engine to stop under load.
- 🔍 Failure of the idle valve (if any) breaks the power supply chain when the ignition is turned off.
⚠️ Attention: When blowing the carburetor with compressed air, be sure to remove all rubber seals and diaphragms. A powerful jet of air can irrevocably deform the rubber, after which the carburetor will have to be changed.
If adjustment doesn't work and all the elements are intact, maybe the carburetor itself has a factory defect or a critical wear on the internal channels. LifanSometimes it is more rational to purchase a new original or high-quality analog carburetor than to try to revive a worn-out node.
Frequently Asked Questions (FAQ)
Why does the Lifan engine stop when you open the valve?
It's probably a transient maladjustment or a major fuel jeekler, and it could be a poor medium-rev mix, or try to twist the mix quality screw a little or clean the jeeklers.
Which gasoline is best used for Lifan engines?
The optimal fuel is unleaded gasoline with an octane number not lower than AI-92. The use of fuel with an octane number above AI-95 does not provide advantages, and fuel below AI-92 can cause detonation and overheating.
How often should the carburetor be cleaned and adjusted?
Preventive cleaning is recommended once a season or every 100 hours, adjustment is required as necessary: if the engine operation has changed, there is an unstable idling or operating conditions have changed (for example, altitude).
Can I wash the carburetor in an ultrasonic bath?
Yes, it's an effective cleaning method, but only after the complete dismantling, all rubber and plastic parts need to be removed, because ultrasound can destroy them. Metal parts clean perfectly.
What if the quality screw of the mixture does not affect the engine?
This indicates that the idling channel is either completely clogged or has a critical air suction, and the screw may be twisted too far or twisted to the point, going beyond the range of adjustment.