Keihin carburetor (Japan) for motorcycles: maintenance, adjustment

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

Repair, adjustment and cleaning of the carburetor is a rather complicated procedure. However, having delved into the technology of its implementation, each owner of a motorcycle or scooter will be able to perform all the actions on their own. To do this, you need to familiarize yourself with the details of the implementation of this process, as well as allocate a sufficient amount of free time.

The Japanese-made Keihin carburetor has the same structure in all models. For other manufacturers, the principle of cleaning and tuning is carried out similarly. Therefore, as an example, this brand of carburetor is ideal. The performance of the motorcycle depends on the correct and responsible approach to cleaning and adjustment.

Carburettor Service Needed

Having a Honda, Kwasaki, Navigator or other two-wheeled motor vehicles, you should understand the importance of periodic maintenance of the carburetor. Power, ease of start, speed and control of the motorcycle depend on this system.

In order for the cylinder block to be supplied with the same quality fuel mixture, it is necessary to correctly regulate the operation of the carburetor. Synchronization allowsadjust the amount of gasoline and air that, when mixed, enter the engine.

Experienced drivers know that the carburetor on a scooter needs to be not only adjusted, but also cleaned during maintenance. Gasoline contains a certain amount of additives, impurities. When the engine is running, they settle on the walls of the system, forming pollution of the jets. To ensure that the carburetor performs its functions in full, it is required to periodically clean it from dirt and deposits accumulated inside.

When is maintenance required?

Carburetor (Keihin PZ30, CVK - it doesn't matter) of all popular models has a similar maintenance principle. Therefore, the signs of the need for this procedure in all cases will be similar symptoms.

The main reason for the need to adjust the carburetor is the uneven operation of the motor. It shows up at idle. There may also be pops coming from the muffler, increased gas mileage. The driver should periodically pay attention to the appearance of the candles. Significant changes in their color indicate violations of the preparation of the fuel mixture.

Candles can be considered the main indicator of carburetor performance. If they are white, the mixture is considered lean. Too much soot on candles indicates the preparation of a rich mixture. This is a departure from the norm. The cause may be a carburetor clogged with dirt or a failure in its settings. In this case, maintenance is carried out as soon as possible. The system should also be cleaned periodically. It depends on how often the motorcycle is used.

Carburettor removal

To clean the Keihin carburetor, it will need to be dismantled. To get to it, you will need to remove the airbox and gas tank. Then the manifold pipe clamps are loosened. The suction cable (enricher) is dismantled.

Honda scooter and other models of similar vehicles have a system of carburetors that are in the same row. They do not need to be separated for cleaning. However, to replace the seals, you will have to disassemble the ruler.

When dismantling, the carburetor block is removed, as well as the throttle cables. Now you can easily perform system maintenance. The top covers must be removed (screws are unscrewed). Next, you need to inspect the condition of the gaskets, needles and rubber bands.

The insides and the carburetor itself, as well as the parts around it, must be thoroughly cleaned. For this, a bath of gasoline and a regular paint brush will do.

Disassembly of the block

If you need to disassemble the carburettor block, the next step is to remove the intermediate plate between them and the air filter. Next, you need to unscrew the bolts on the bar holding the block together. Keihin CVK or other model usually requires a lot of physical effort here. You will most likely need to use a T-handle screwdriver.

Next, you need to disconnect the return spring. To do this, the bolts are also unscrewed in the appropriate places. The bar will easily slide off and detach from the structure.

A long bolt fixes the carburetors between themselves. It must also be dismantled. You can disassemble the block. The first carburetor is removed and the spring is laid aside. They should not be confused in places (differ in size). Then the case is cleaned from the outside.

Maintenance of the carburettor block

The carburetor on the scooter may need a diaphragm replacement. In some cases, it is also necessary to completely replace one of the block elements. The internal metal surface of the instrument may oxidize over time. Therefore, the diaphragm will need to be replaced. It is very carefully removed with a screwdriver.

This item will be available with a dosing needle and a flap. Further, if necessary, old components can be replaced.

After that, you need to unscrew the screws of the float chamber. Its cover is removed. You can evaluate the work of the float by lightly pressing it. If this element springs, then its work is correct. Replacement is not required. When disassembling, it is very important to use a screwdriver of the correct size. All work must be done very carefully.

Cleaning

Keihin carburetor after disassembly requires thorough cleaning. To do this, you need to purchase a special tool. It should not destroy the rubber seals. There are many such cleaners on the market. It is convenient if the product is in a bottle. Using a special tube, it will be easy to spray it all over the mechanism.

Work must be carried out outdoors. Solvents contain many hazardous components. Therefore, indoors, such work is highly discouraged.

Under pressure, the carburetor is purged with air. If necessary, some areas can be cleaned manually with cotton swabs. If the length of the springs is significantly different (by 1.5 mm), they must be replaced.

Assembling the carburetor

After proper cleaning and replacement of all obsolete parts, the carburetor is installed in its original position. Assembly is carried out in reverse order. When installing the diaphragms, it is necessary to properly install the return spring in the seat. If it is not easy to install it in place, you just need to turn the part.

When installing the shutter, you must follow the position of the needle. She must not move to the side. If necessary, the parts must be lubricated with grease.

Then the cylinder block is assembled in reverse order. To do this, you need to prepare the appropriate tool. All carburetors are different. Therefore, when disassembling, it is necessary to number them. Installing a carburetor requires a scrupulous attitude. All bolts, springs must be assembled very carefully. It is better to write down the sequence when disassembling so as not to lose a single structural element.

Sync

Keihin carburetor adjustment required after cleaning. You can start with synchronization. This is an easy procedure. Butit needs a synchronizer. This device checks for rarefaction.

The motorcycle must be warmed up to the operating temperature of the motor. Next, the tank and filter are removed. The synchronizer will help to establish the same rarefaction in the collector. The device connects to it. Engine starts.

According to the readings of the sensors, the valves need to be adjusted. They should respond (but not strongly) to changes in sparsity. If the synchronizer needle does not perceive changes, the valve must be released. The process is carried out using the appropriate screws on the carburetor. First adjust the right and left screws. Only then can the central lever be adjusted.

Idle adjustment

After high-quality cleaning, the idle speed is adjusted. To do this, the engine must be well warmed up. To do this, you need to start the vehicle and wait 10-15 minutes.

Next, refer to the manufacturer's instructions. It indicates where the adjustment screws are located. With this knowledge, you can start the process. It is better to mark the screwdriver with which all settings will be carried out. On one side it is necessary to stick a marker. This will allow you to understand how many turns have been made.

At idle, tighten the corresponding screw. If it is clamped, the speed will increase, and vice versa. Adjustment is carried out until stable engine idling is obtained.

Adjusting the quality of the mix

If the idle speed adjustment was successful, you can proceed tosetting the quality of the fuel mixture. She should not be too poor or rich. Adjustment is made using the adjusting screw or by moving the needle in the throttle valve.

Before tuning, the motor should be warmed up. This procedure is carried out only for a clean carburetor. Most often, for normal operation of the system, it is required to unscrew the screw from the extreme position by 1.5-2 turns. But many reasons affect this indicator.

If the screw is turned clockwise, the mixture is enriched and vice versa. If the needle is lowered, the mixture will become leaner. With a combination of both settings, it is possible to achieve accurate operation of the fuel supply system to the engine. If the procedure is done correctly, the motorcycle will accelerate smoothly. There will be no jerks when driving

Fuel level adjustment

A Keihin carburetor adjustment is completed by checking the fuel in the float chamber. To do this, prepare a transparent tube. It is located at the bottom of the system. The drain screw must be unscrewed. Further, the tube rises up, in the opposite direction from the carburetor. Checking the fuel level.

Checking is carried out with the motorcycle engines running. The tube must always be higher than the carburetor. The fuel should be slightly lower than the curb of the cap.

By reviewing the Keihin carburetor, as well as its design and maintenance, each vehicle owner will be able to clean and tune it himself. This will extend the life of the vehicle, make the movement on it safe and comfortable. Almost all actions the driver will be able todo it yourself, without contacting a car service.