139QMB (scooter engine): characteristics and device

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

A wide range of Chinese scooters is presented on the Russian motorcycle markets, which, despite the variety of brands and models, are equipped with only two types of engines - two-stroke and four-stroke.

139QMB engine history

The largest and most popular category is the 4-stroke engine, with the 139QMB being the most sought after and well-known. The first model of the 139QMB engine was developed in the 90s by Honda. Ten years later, the development was used by China for the mass production of engines. The final version, after numerous revisions, has become one of the best engines for motor vehicles: today Japan is actively engaged in its purchase and subsequent sale under the Honda brand.

Engine Features

The official manufacturer of the 139QMB scooter engine is Hongling Corporation, which equips motor vehicles with this engine not only of its own brand, but also of other brands.

The corporation sells power units to other manufacturers. The motor itself is very recognizable: the features of the 139QMB engine and its marking applied to the left side of the crankcase immediately make it clear whichit is the scooter's heart that beats.

The motor has no flaws, does not require special treatment and calmly takes down a little carelessness and negligence. The manufacturer gives a guarantee for its products, covering the first 5 thousand kilometers. This mileage is enough for the new 139QMB 4t scooter engine for a full run-in and grinding in of all elements and components of the systems.

The total operating life of the motor is about 20 thousand kilometers, with the exception of 5 thousand break-in at an average driving speed of 90 km / h. The specs of the 139QMB engine are good, with enough power to power a two-seater full-size scooter.

Analogues - engine 1P39QMB

Chinese developers have created an analogue of the Japanese engine 139QMB - a motor marked 1P39QMB, which in its appearance completely repeats the original. Despite all the similarities, you can still find differences: the valve clearances of the 1P39QMB are not adjustable. A similar situation with the carburetor: before direct operation, it requires thorough cleaning and correct adjustment. Chinese copies of 139QMB engines, of course, cope with their task, but their main purpose was to reduce the total cost of motor vehicles. Budget options for scooters are equipped with precisely such versions of engines that are good only for short trips at low speeds.

Before starting operation, a full run-in of the 1P39QMB engine is mandatory. Optim althe engine operation mode begins only after 2 thousand kilometers, however, after 10 thousand kilometers, all its technical characteristics fall, and it loses dynamics and power.

Engines 157QMJ

In addition to the very popular model - 139QMB engines - Hongling Corporation also produces other versions of power units, one of which is 157QMJ. It is installed on expensive models of scooters of famous brands. In terms of its technical parameters and indicators of functionality and reliability, this version is a complete analogue of 139QMB. In addition, the design features of the model strongly resemble other mass-produced Japanese engines.

The advantage of 157QMJ is an increased operational resource - about 25 thousand kilometers. The engine boasts powerful dynamics and high top speed. However, he also has his minus - too high a price compared to previous versions of motors.

Engine D1E41QMB

The D1E41QMB motor is the only two-stroke engine made in China. A distinctive feature of this motor from other representatives of the category of power units is the presence of a chain reverse gear in the design. The uninterrupted operation of such an engine is ensured by mixing gasoline and oil in proportions of 40 to 1. The working life of the engine is about 10 thousand kilometers, after which it becomes necessary to repair. The disadvantage of the engine is the forced speed limit - no more than 50 km / h.

Engine break-in

Incorrect break-in of the 139QMB engine in most cases leads to failure of the piston system. Friction occurs between the parts of the new CPG, which leads to an increase in engine temperature.

The scooter engine is broken in as follows:

1. The scooter is placed on the center stand.
2. For 5 minutes, the engine starts at idle, the field of which is cooled for the same time.
3. The engine also runs for the next 10 minutes, after which it cools down for 15 minutes.
4. The engine is restarted for 15 minutes, then turned off and left to cool for 15 minutes.
5. The scooter restarts for 30 minutes, then turns off and leaves for 20 minutes.

After carrying out such manipulations, you can run the scooter itself. The throttle stick in the first 100 kilometers should not be unscrewed by more than 1/3 of its full travel. The maximum speed must not exceed 30 km/h. At 15-20 km/h, the speed can be increased for the next 300 kilometers - during this time the engine should more or less reach its potential.

After the break-in process, the oil must be changed.

The engine valves are adjusted every 500 kilometers.

Engine Tuning

The first thing they try to change when tuning the 139QMB engine is the cubic capacity. To this end, the standard piston system is replaced by 82cc. At the same time withthis installs a new cylinder head with larger valves. The piston system changes along with the camshaft, since it requires more air-fuel mixture to work correctly. The new camshaft will help increase the amount of incoming fuel mixture, but the carburetor will still need to be replaced.

Replacing the carburetor

A standard carburetor after replacing the elements described above will not work for the further operation of the engine - instead, a budget CVK18 is installed, equipped with an 18 mm diffuser. At the same time, it is advisable to purchase a set of jets of different sizes, since you will have to sweat a lot to correctly set up the carburetor.

Air filter

It is not recommended to completely remove the filter element or replace it with a filter of zero resistance - this can lead to contamination of the carburetor. Experts usually recommend removing the plug that is installed at the inlet to the air filter.

Many of the reviews that have affected the assembly of the 139QMB engine after tuning, they talk about installing a zero-resistance air filter. Despite the fact that this solution is one of the most popular, it is not always appropriate and justified.

The reason lies in the fact that the installation of such a filter leads to rapid contamination of the carburetor. The main reason for using a zero resistance filter is the need for a richer fuel mixture after installing an oversized piston. However, to avoid thisyou can install a new camshaft and replace the jets in the carburetor.

It is worth noting separately that the standard carburetor equipped with a 16 mm diffuser is installed together with a 62-72cc piston system, while the 82cc piston system is equipped with a carburetor with a 18 mm diffuser.

For replacement, it is advisable to purchase a set of jets, since several different options may be needed to adjust the carburetor.

Variator

Increase the efficiency of the standard scooter CVT and use its full potential only after installing an enlarged belt. At the same time, a set of new weights is purchased - they should all differ in weight. For the variator, the necessary weight of the weights is selected very carefully and painstakingly, since the maximum speed of the motor vehicle and the dynamics of its acceleration depend on them.

Switch

To tune a scooter, it is enough to purchase a classic switch without speed limit. For a four-stroke engine, a special universal switch will be the best option on the market.

Results

The 139QMB engine is one of the most popular and demanded power units for motor vehicles. The listed manipulations with the motor are one of the least costly and effective tuning options. It is the most appropriate and budgetary, since replacing engine parts with better ones will cost more than purchasing another model of a scooter with an improvedengine.