Which direction is the motorcycle fuel tank switch normal?

Isn't there a handle on the car fuel tank switch? Generally, the tail of the handle is downward (that is, the arrow is upward) for normal oil use, and vice versa for standby oil, and horizontally for closed oil circuit. Always use oil normally.

Motorcycle consists of five parts: engine, transmission system, running system, steering, braking system and electrical equipment. The overall structure of motorcycle and the names of its components.

engine

1, characteristics of motorcycle engine

(1) The engine is a two-stroke or four-stroke gasoline engine.

(2) Adopt air cooling, including natural air cooling and forced air cooling. The general model adopts natural air cooling, relying on the air blowing through the cylinder head and the radiator on the cylinder liner to take away the heat. In order to ensure the cooling of high-power motorcycle engine at low speed and before driving, forced air cooling is adopted, equipped with a fan and an air guide cover, and the heat sink is cooled by forced air.

(3) The engine speed is high, generally above 5000 rpm. The rising power (the effective power per liter of engine displacement) is relatively large, generally around 60kw/ liter. This shows that the motorcycle engine has a high degree of reinforcement and a small overall size.

(4) The engine crankcase, clutch and gearbox are designed as a whole with compact structure.

2, the body

The engine block consists of three parts: cylinder head, cylinder block and crankcase. The cylinder head is made of aluminum alloy with fins. The new four-stroke motorcycle engines all adopt overhead valve, chain drive and overhead camshaft structure. The cylinder block adopts bimetal (aluminum fins cast outside the wear-resistant cast iron cylinder liner) to obtain better heat dissipation effect.

Some motorcycles use wear-resistant cast iron cylinder blocks, such as Changjiang 750 and Jialing JH70. On some small mopeds, such as Yu He YH50Q small displacement (50 cubic centimeters) engine, the inner wall of aluminum alloy cylinder is plated with 0. 15 mm hard chromium layer. Crankcase is made of aluminum alloy by die casting, and consists of left and right boxes. Some motorcycles are equipped with buffer blocks between radiating parts to suppress the noise caused by vibration of radiating fins.

3. Crank connecting rod

The crankshaft of motorcycle engine is a combined type, which is formed by pressing a left crankshaft, a right crankshaft and a crank pin. Ball bearings are installed on the main journals of the left and right half shafts to support the crankshaft on the crankcase.

Flywheel, magneto and clutch driving gear are installed at both ends of crankshaft respectively. The connecting rod has an integral structure, the big end is annular, and a needle bearing and a crank pin are installed inside to form a crank connecting rod group. When installing a piston ring on a two-stroke engine, it is necessary to align the opening of the piston ring with the locating pin in the piston ring groove to prevent the piston ring from rotating in the ring groove, causing air leakage and scratching the intake and exhaust ports on the cylinder liner.

4. Vaporizer

Carburetor is an important part of motorcycle fuel supply system, which is located between air filter and engine intake. Motorcycle engines generally adopt carburetor, plunger throttle valve and float chamber throttle valve with horizontal intake flow direction. The carburetor structure mainly consists of a float chamber and a mixing chamber. The float chamber is located below the carburetor, and the oil pipe is communicated with the oil tank through the throttle switch. The oil level in the float chamber is maintained at a certain height through the needle valve on the float, and the oil supply pressure is stable.

The function of the mixing chamber is to evaporate and atomize gasoline and mix it with air, so that the engine can get the required mixture at various loads and speeds. It consists of throttle valve, injection needle, injection pipe, gas path and oil path.

By turning the throttle handle of motorcycle to drive the throttle steel wire to hang the rope, the throttle valve and the fuel injection needle are controlled to move up and down, and the cross section and fuel supply of the intake throat are changed to meet the needs of mixed gas at different speeds and loads. Idle speed adjusting screw is installed on one side of carburetor to adjust idle speed. Idle stop screw is used to prevent the throttle from rotating and adjust the minimum opening of the throttle. There is a return spring above the throttle to keep the throttle closed when the throttle handle is not turned.