Motorcycle carburetors take air and mix it with fuel. Numerous factors can cause a motorcycle carburetor to fail. As a rule, motorcycle carburetors are upset by vibration. Manufacturers such as Mikuni, Keihin and S&S sell original equipment and aftermarket carburetors for numerous motorcycles. The details vary, but the setup principles are the same for all of these devices. Here, in particular, is how to adjust the carburetor that Harley-Davidson has used since 1989.
Synchronizing carburetors on a motorcycle
Synchronizing motorcycle carburetors is a precise procedure, but not very difficult. To carry out this action you will need a synchronizer. This is a set of meters that check for sparsity. And the meter itself is a vacuum sensor with a valve that smoothes out the oscillations of the needle. Sets with two or four heads are used. A four-head device is best.
Synchronization procedure:
- The motorcycle warms up to the required temperature.
- The tank is removed, then the filter.
- Now you need to choose the places where to connect the device heads. What is the essence of synchronization? It is necessary to set the same rarefaction formed in the collector. Because through it the combustible mixture enters the inlet cylinders from the carburetor. Therefore, connection points must be selected in the collectors.
- The device connects to the found collection points. It happens that it is difficult to get to these points, and then the carburetors can be raised. To do this, they are pulled out of the pipes, and after connecting the device, they are seated in place.
- The motorcycle starts. The valves of all sensors need to be adjusted. It is necessary that they react to any changes in sparseness, but do not fluctuate much. The valve is released if the arrow does not respond to any changes.
- Three screws can be seen on the carburetor. It is with their help that synchronization is carried out. One of them, the first, is located between the first two carburetors. We synchronize them. To synchronize the second pair of carburetors, the third and fourth, a third screw is used. He is between them. The central screw synchronizes all carburetors with each other.
First of all, the left screw and the right one, and only after that the central one.
- The first pair of carburetors is synchronized.
- The second pair of carburetors is synchronized.
- All readings are now aligned using the center screw.
- After the synchronization is completed, we apply gas, sharply raise the speed and reset again. All readings are synchronous.
- If this is not the case, the procedure, starting from the seventh step, must be repeated.
You can change the oil or carry out the synchronization procedure yourself. But adjusting a motorcycle carburetor is the more difficult part of the repair. And if you don’t have the skills to do this kind of work, it’s best to turn to professionals.
Signs that adjustment is needed
Based on certain signs that appear in abnormal engine operation, we can conclude that the carburetor needs adjustment.
The list of deviations is quite wide:
- Do-it-yourself carburetor adjustment for VAZ 2107
- the power plant does not develop the required power under load;
- when the scooter accelerates sharply, failures in engine operation are felt;
- a cold engine is difficult to start with the starter after a long period of parking;
- the scooter's power unit consumes fuel in increased quantities;
- there is no quick response of the engine to a sharp turn of the accelerator handle;
- The engine may suddenly stop due to insufficient fuel mixture.
The carburetor should be adjusted if there are signs that adjustment is necessary.
If one or more of these symptoms is present, you should adjust the carburetor, and then diagnose its condition and check the operation of the engine.
Installation and configuration
Before adjusting a new K 65 carburetor, it must be installed and adjusted.
First you will need to remove the carburetor cap. The throttle spring holds the needle through the lock. It has one round and two shaped holes. A round slot located in the center serves to attach the throttle cable. The T-shaped hole is necessary for attaching the propeller rod.
Having installed the carburetor on the engine, a cable is connected to the throttle, and the cover is secured.
Use the throttle to raise the throttle and check whether the diffuser opens completely. These actions should be performed several times. The diffuser should open and close freely without jamming.
Next, use a screw to raise the throttle so that a gap of 3 mm appears between its bottom edge and the diffuser generatrix.
If the K 65 device (carburetor) has a corrector, it should be removed as an assembly and the cable should be attached to the piston. After this, you should install the unit in place.
Next, you should adjust the position of the stops of the cable sheaths so that their free play is 2-3 mm.
The screw must be tightened until it stops, then loosen it by 0.5-1.5 turns. The fuel hose is connected to the fitting. Fuel should not leak at the connection points.
Then the peak starter turns and the crankshaft rotates 3 turns. The ignition is turned on and the start is made. After warming up, the starter or corrector can be turned off.
How to adjust the carburetor on a motorcycle
If the synchronization of carburetors is carried out so that the amount of the combustible mixture is adjusted, then they are adjusted to improve the quality of this mixture supplied to the cylinders from the carburetors.
The Keihin carburetor for a motorcycle is adjusted in the same way for different models and brands of motorcycle. It is best to adjust carburetors at the same time as cleaning the carburetors. Because most often a poor-quality combustible mixture is formed when the jets are not clean enough.
The carburetor for the Ural motorcycle and other domestic motorcycles has been used from St. Petersburg since ancient times. It was constantly modernized and changed. And today this is a completely new device, which is called K-68. Today the Ural is the only motorcycle in the world that uses carburetors with variable vacuum.
To keep your motorcycle running properly, you need to know how to adjust the carburetor. And this needs to be done under certain weather and a specific road. Carburetors installed on motorcycles differ slightly from each other.
Attention: Motorcycle carburetors are designed specifically, and all its systems must work in parallel. The slightest mistake in this type of work will lead to other errors occurring. Care is required here.
To the question of how to properly set up a carburetor, we will answer this way, only in strict sequence.
- The float chamber contains fuel. Its level needs to be adjusted. Read the instructions carefully. The required float height is indicated there. The tongue is bent for adjustment. This adjustment is only necessary for precise adjustment.
- Idling. In this case, the carburetor operates when the throttle valve is closed. Idle speed is adjusted. To do this, you need to use the idle system jet and screws that regulate the quantity and quality of the mixture formed.
- Transitional mode. Here the throttle valve opens to a quarter. It is very important to choose the right jet and adjust the idle system.
- The throttle valve is partially open, up to seventy-five percent. Here you need to pay special attention to the gap that forms between the needle and the tunnel where the needle moves. The composition of the mixture depends on the diameter of the needle. To access this needle, on most motorcycles the carburetors will need to be removed.
- The throttle valve is fully open. The size of the fuel jet used is important here. The spark plug insulator, or rather its color, will help you find out whether you have adjusted the carburetors correctly or not. When properly adjusted, its color is dark brown.
This work is complex and small. But the reliable operation of your motorcycle engine is entirely dependent on this work. Constant practice and experience will lead you to success.
