Asynchronous operation of two or four carburetors primarily leads to increased vibrations when the engine is running. Dissynchronization of carburetors occurs due to uneven accumulation of contaminants in the fuel system, due to wear of mechanical parts and drives. The manufacturer's instructions recommend checking the timing of the carburetors every 6,000 km.
It is necessary
Synchronizing vacuum gauge
Instructions
Step 1
The job of timing carburetors is to set the same gap between the throttle valves and carburetor bodies when idling. The easiest way to achieve this is to set equal vacuum in the engine intake pipes. To perform carburetor synchronization yourself, you will need a synchronizing vacuum gauge. This device consists of two or four vacuum gauges. All the devices included in its composition are designed to work with the corresponding vacuum that occurs in the exhaust pipes at idle speed. In addition, the vacuum gauges are calibrated for equal readings at an equal vacuum and are equipped with devices that reduce the oscillations of the arrows when the air flow in the intake pipes changes.
Step 2
The two-cylinder engine is tuned by a block of two vacuum gauges, the four-cylinder - by a block of four. More advanced carburetor timing gauges are equipped with bar graph vacuum displays. The bars on the display must be the same height to synchronize the carburettors. Liquid crystal vacuum gauges are equipped with coarse and precise operating modes.
Step 3
Adjust the damper actuators before synchronizing the carburetors. To synchronize the carburetors, remove the gas tank, air filter (if necessary) and find the connections for the vacuum gauge pipelines. On older and less sophisticated motorcycle models, they can be found by special plugs on the intake pipes. On modern motorcycles, intake vacuum is used to control various devices. Take advantage of the tubes of these devices by connecting them to the vacuum gauge through tees. At the same time, remember which pipeline, from where it was removed! If the vacuum gauge connections are difficult to reach, you may need to remove the carburetor assembly.
Step 4
Start the engine and warm it up. Adjust the vacuum gauge valves so that they fluctuate as little as possible, but at the same time respond to the slightest change in vacuum. This procedure may need to be repeated if the carburetors are synchronized further. If the arrow of the device does not respond to changes in vacuum, loosen the valve, if it starts to oscillate, tighten the valve. Check the number of idles for which the engine is designed and set these rpm. An error in setting the revolutions will lead to false synchronization of the carburetors: the instrument readings will indicate that synchronization has been achieved, but when the revolutions are changed, this synchronization will disappear.
Step 5
Different engines have different carburetor timing adjustments. Usually 3 screws are used for this. The base screw is located between the carburetors and controls the valves of the 1st and 2nd cylinders. In four-cylinder engines, the second screw adjusts the cylinder flaps in pairs I-II and III-IV. The third one controls the flaps of the III and IV cylinders. Adjust the first screw first, then the third, and last the center.
Step 6
When consistent gauge readings are achieved, check the timing of the carburetors. To do this, sharply increase the engine speed and drop them to idle. The synchronization of the carburetors should not disappear. The instrument hands should return to the same position for all.
