1 .car model selection
The first problem to be solved when buying a car is to understand your own needs. If you don’t understand your own needs, it is best to test drive more models before buying a car. The premise is that you must have a motorcycle driver’s license and test drive as many models as possible. Street cars, sports cars, cruisers, pedals, adv and other types of riding experience are very different, and the market positioning is also very clear. Street cars are flexible, which is conducive to shuttle riding in urban areas. Better handling, cruiser riding posture is stretched, a model that is handsome but not fast, pedals are said to be the ultimate destination of a knight, first of all you must be a knight, so it is the last Buddhist model after playing with many models when you are young Choose, of course, the current pedals are also very radical, so you can test drive, if you like it, it is recommended to choose, because money is hard to buy you happy, adv models are very popular now, represented by BMW's waterfowl, it is a load-carrying The models of Poetry and Yuanyuan have an upright riding posture and are comfortable for long-distance riding.
2 .selection of parameters
Common parameters of locomotives are:
(1) Engine parameters: displacement, type (several cylinders), compression ratio, emission standard, cooling method, maximum power, maximum torque, etc.
(2) Other parameters: car body specifications (wheelbase, frame, brake form, curb weight, shock absorber form, tire specifications), appearance specifications, fuel tank size, etc.
Engine parameters directly affect the acceleration performance of the locomotive. The relationship between displacement and fuel consumption is not directly proportional. If the fuel consumption of a small horse-drawn car is the same and affects the life of the engine, the common types of engines are horizontal bars, parallel bars, and four-cylinders. Under the displacement, the single cylinder has strong low-torque explosive power, low fuel consumption, simple structure, and convenient maintenance, but the top speed is low, and the larger the displacement, the more obvious the vibration. The twin-cylinder engine has the characteristics of smoother operation, higher top speed and faster acceleration. But with low torque difference, the post-maintenance room is between the horizontal bar and the four-cylinder. The four-cylinder engine runs smoothly, with high top speed and fast acceleration, and the sound performance will be more vigorous and powerful.
Generally speaking, when the other designs of the engine remain unchanged, the higher the compression ratio, the greater the power, the higher the efficiency, and the better the fuel economy. However, if the compression ratio is too high, the stability will decrease, and the life of the engine will be shortened. Using low-grade gasoline for a high-compression ratio engine will cause knocking, and using high-grade oil for a low-compression ratio engine will cause "flame retardation".
Cooling methods include air cooling, water cooling, oil cooling, etc. If the small machine is air-cooled, it is recommended for large machines to be water-cooled, oil-cooled or water-oil cooled.
The maximum power directly affects the top speed of the vehicle. The higher the power, the higher the top speed. The maximum torque directly affects the acceleration performance of the vehicle. The greater the torque, the better the acceleration performance (the stronger the pushback feeling), and at what speed the maximum torque of the engine is output The maximum power and the maximum power determine the performance of the engine. When the maximum power and maximum torque are the same, the engine that can output the maximum torque and maximum power at a lower number of revolutions is more irritable.
The smaller the wheelbase in the car body specification, the more flexible it is. The wheelbase of a street car is generally smaller than that of a cruiser. The frame structure defines the outline of the entire car, and it must bear the weight of the rider, the inertial influence of acceleration and deceleration, and cornering. deformation etc. The shorter the distance from the faucet to the central axis of the frame, the greater the rigidity. The common ones are masonry frame, double-spar frame, steel pipe frame, and cradle frame.
Braking forms are generally disc brakes and drum brakes. Drum brakes have high braking force but serious heat attenuation, and are not suitable for long-term braking. ABS disc brakes are now the mainstream braking form.
The shock absorber is simply divided into inverted and upright. The inversion is friendly to the ground and improves the grip of the tires. The upright is friendly to the rider and is comfortable to ride, but the grip of the tires is not as strong as the upside down.
The tire specifications are generally narrow at the front and wide at the rear, which is conducive to steering control and stability. It is more stable when the rear wheel is wide and bends.
The appearance specification is mainly about the sitting height, which is just right when riding on the bike with the soles of the feet on the ground. If the sitting height is too high or too low, it is not conducive to daily riding.
The size of the fuel tank directly affects the battery life. Generally, the battery life of street cars and sports cars is 200 kilometers. The fuel tank of Dongfeng nk650 is 17L.