There are two reasons for this:
1. Since all operating characteristics of the engine are related to the carburetor, such as acceleration, starting, fuel consumption and so on. Therefore, when judging the cause of the motorcycle failure, the failure of the electric device or other mechanical components is often confused with the carburetor, and the carburetor is replaced by a carburetor failure. For example, the filter impurities block the carburetor, and the replacement of the new carburetor is eliminated, but the fundamental problem is not solved.
2. The quality problems of related parts and components have greatly shortened the life of the carburetor. Such as the reduction of cleanliness, increase the wear of carburetor parts and so on. Many merchants often encounter similar problems in their cooperation with motorcycle manufacturers.
Some typical failure analysis and elimination methods for carburetor:
According to the national standard, under the premise of correctly using the carburetor to start the enrichment device, the pedal or electric starting time exceeds 15 seconds, and the engine still cannot maintain continuous operation and is judged to be difficult to start. The reasons for starting difficulties and the corresponding troubleshooting methods are as follows:
1: There is no fuel in the carburetor float chamber.
The carburetor inlet passage is blocked. The analysis and troubleshooting steps are as follows:
Open the carburetor float chamber and check if the oil inlet needle valve is dropped when the float is dropped. If the needle valve does not follow the movement of the float and is still tightly coupled with the needle seat, it can be judged that the needle valve and the valve seat are stuck to cause the oil passage to be blocked. This fault is generally caused by the condensation of the gasoline gel between the needle valve and the valve seat. It can be washed with alcohol or acetone. Such failures often occur on motorcycles that are not used for long periods of time. In particular, after the engine plant and the motorcycle factory are installed, the gasoline in the carburetor float chamber is not exhausted. In the case of a long inventory or sales period, the gasoline colloid condensation will occur, causing the carburetor performance failure.
Remove the float and needle valve, connect the gasoline from the carburetor inlet nozzle, observe the outflow condition of the gasoline from the valve seat. If there is no gasoline outflow, the oil inlet passage is blocked. Use a compressed air air gun to blow it to make it clear. In addition, the oil pipeline blockage indicates that a large amount of impurities enter the inside of the carburetor. The root cause is the failure of the fuel filter. Therefore, the fuel filter should be inspected while cleaning the carburetor.
2: Starting the enrichment device The carburetor is designed to improve the starting performance. The starter enrichment device is specially set. The motorcycle start enrichment device mainly has two structural forms:
The choke mechanism: the choke mechanism is a relatively simple mechanical device generally used for straddle-type vehicles. It can be judged whether it is normal or not by the method of pulling the choke handle to observe whether the choke flap moves with it.
Bypass enrichment system: The bypass enrichment system has many classifications, and the most widely used ones are electrothermal and manual bypass enrichment systems. The electric bypass enrichment system is generally used for scooters.
The troubleshooting and troubleshooting steps are as follows:
A: After 4 to 5 minutes after the motorcycle door is opened, the hand touches the electric heating starter and the plastic case of the rich valve. If there is thermal feeling, the circuit is normal; otherwise, the circuit needs to be checked. If the circuit at the interface of the rich valve is normal, the enrichment valve is judged. It has been damaged and needs to be replaced.
B: After removing the start-up enrichment valve and turning on the circuit for 0 to 5 minutes, observe the movement condition of the enrichment valve plunger. If the enrichment valve plunger continues to extend with the spring, the enrichment valve is normal; otherwise, the enrichment valve is in the middle. The PTC heater is damaged and the enrichment valve assembly needs to be replaced.
C: Clean the enrichment channel on the carburetor body with compressed air.
3: The phenomenon that the idle speed is low and the idle speed is low: the engine can be started but cannot be stably operated for a while and then turned off.
Remedy: Adjust the carburetor plunger adjustment screw, screw it clockwise, the engine speed increases; counterclockwise rotation, the engine speed decreases. Generally, the engine speed can be adjusted to about 1500 rpm (straight ride) and 1700 rpm (scroller).
4: Incorrect starting method The incorrect starting method basically appears in the use of the starting enrichment device. The common incorrect starting methods are:
Do not use the starter enrichment device. This is caused by the user's incomplete knowledge of the function of the motorcycle, because even if the starter enrichment device is used at normal temperature, the starting performance is greatly improved.
The start enrichment device (for the choke mechanism and the manual bypass enrichment device) has been used during the starting process. When the start-up enrichment system is working, the engine is supplied with a very rich mixture. If the enrichment device is used during the start-up process, a large amount of rich mixture enters the cylinder and “drows†the engine, making the start-up difficult.
The correct use of the enrichment device is: if the engine still cannot run after starting 3 to 4 times, close the enrichment device, and slightly rotate the throttle handle to raise the carburetor plunger and start again.
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