Old drivers driving motorcycles, often encounter someone asked: motorcycle plus 92 or 95 gasoline, is it the higher the number, the better?
The same problem is often mentioned in cars, and now motorcycle drivers are paying attention; With the increasing number of heavy motorcycles, more and more drivers are using motorcycles as "toys" instead of commuting tools. These "big toy cars" are expensive and should be paid attention to.
So what's the right answer?
Without entanglement, the correct answer is to look at the engine parameters of the vehicle, to the compression ratio as a reference for oil selection; Here are a few motorcycles with different positions to find out.
1. Commuter pedal, refer to construction Qiao, this car is a single-cylinder four-stroke air-cooled 125cc engine, compression ratio is 11:1, the recommended gasoline label is 92; The compression ratio of this engine is relatively high, but the compression ratio of motorcycle engines is generally not low, so this standard can be used 92.
2. Commuter straddle-ride: Wuyang Honda CG125, the engine is naturally 125cc single-cylinder four-stroke with a compression ratio of 9.2:1, which is a relatively low standard, so it is only suitable to use No. 92 gasoline; If you use the high grade 95 gasoline, you can say that the engine is "not digestible."
3. Street car with medium displacement: Chungchun 250NK, the engine is a single-cylinder four-stroke engine of 249cc, and the compression ratio is 11.3:1, which exceeds the standard of Qiao; This standard will use 95 gasoline, you can think of 11:1 as the watershed, beyond the standard is generally recommended to use 95 gasoline, 250NK recommended standard is 95.
4. Internet celebrity car Panta Jingira: Equipped with 298cc V-type two-cylinder water-cooled engine, the compression ratio reaches 11.5:1, which is considered as a high compression ratio engine; Therefore, the recommended standard of the original car is also No. 95 gasoline. These cars are not suitable to use No. 92 gasoline, otherwise the detonation combustion may cause serious failure of the pull cylinder.
5. Large Benali Jinpeng 502: equipped with 499.6cc parallel twin cylinder water-cooled engine, compression ratio of 11.5:1, the recommended gasoline label is No. 95 of course; This shows that large and medium displacement motorcycle engines are basically high compression ratio models, compression temperature is too high, in order to prevent fuel detonation combustion must use high grade gasoline.
The last thing that needs to be explained is the concept of gasoline labels.
The gasoline number distinguishes the octane number, which is generally understood as the number representing the proportion of isoctane; For example, 95 gasoline is 95% isooctane, which of course is not that simple. The octane number of isoctane is 100, n-heptane is 0, and fuel ethanol is 111. The higher the octane number, the better the "knock burn resistance" of gasoline. The normal gasoline engine only vaporizes gasoline with high temperature generated by compressed air in the compression stroke and ignits work in the third power stroke. But if the compression ratio is too high and the gasoline grade is too low, then there may be "compression combustion" in the compression stroke; Premature combustion of some gasoline can cause "knock combustion."
The transmission speed of a normal flame is only fifty or sixty meters per second, more than seventy or eighty meters; But the blast flame can travel at over two kilometers per second! Excessive speed can cause the piston to hit the cylinder wall, which is called "cylinder knocking," and it can wear down the liner and cause "cylinder pulling" during the high-speed reciprocating cycle.
So the gasoline label can be raised but must not be reduced, the original car is recommended to use 95 gasoline can not use 92; If the compression ratio is not high and only 95 gasoline is recommended, it is not recommended to upgrade to 95 gasoline. Because higher-grade gasoline is also denser, it doesn't evaporate as effectively during the compression stroke. This is called "engine indigestion." There is no boost in power and carbon accumulation occurs more often.
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