The famous Java 250 motorcycle first appeared in 1972, and then all of Europe was able to see the skill of Russian specialists. In general, the production of 250 cc models from the plant in Czechoslovakia has always been successful, and the Java 250 is proof of this.
Today you are unlikely to see this motorcycle; it was produced for a short time - from 1972 to 1975. But if you were lucky enough to see this unit, consider yourself lucky, because back then it was a real symbol of the motorcycle industry. But any symbol has its own disadvantages and advantages.
Pros:
- reliable engine;
- low fuel consumption;
- stylish appearance.
Minuses:
- lack of details;
- it will be difficult for the buyer to find the motorcycle.
Technical characteristics of Java 250
In general, the Czechoslovak plant began producing 250 cc Java motorcycles back in 1935, so there is another unofficial name for the motorcycle - Java 250 old lady. Today they produce completely different equipment, but the previous serial Javas were made conscientiously and therefore residents of the CIS can still ride such a motorcycle. Let's look at the main characteristics of the serially produced Java 250.
The motorcycle is positioned as a two-seater, and to ensure good performance, an excellent engine with a capacity of 12 to 17 horsepower was installed, depending on the year of manufacture. Accordingly, the curb weight had an excellent indicator - up to 150 kg, and the maximum speed did not exceed 115 km/h. Thus, any owner of this model could easily move both along the highway at high speed and transport heavy loads in rural areas. And with the help of a 15-liter gas tank, the owner could go on a short trip.
The excellent safety of the motorcycle is also considered a big plus; it is equipped with wheels of a standard diameter of 18 inches, which in turn have reliable drum brakes. If you drive at high speed or for a long time, the air cooling system will protect the engine from overheating. An interesting and one of the best characteristics for Java 250 is the “Port control” distribution system.
Bright, stylish, but still Dnepr
Looking at this motorcycle, different emotions immediately appear in me. On the one hand, the author of the project had a hand and spent a lot of time creating this “horse”, but on the other hand, I don’t see much point in them. It is unlikely that this homemade seat will be more comfortable than the standard one.
Exhaust
- the highlight of the whole design. As for me, the “cans” are too massive for the pipes that go directly to the cylinders. I think if they were made thicker in cross-section, this modification would look somewhat more impressive.
The colors here are extremely bright and dull
, but this is
a matter of taste
. And, according to the classics of the genre, we are witnessing the abandonment of the steering wheel and the fact that the author of the project gave preference to clip-ons, completely cutting down the ability to move around on this motorcycle.
Motorcycle review
In appearance you can see an excellent motorcycle with a simple but at the same time thoughtful design. The design of the motorcycle is made with special smooth transitions, and the red color adds charm.
If we return to the technical characteristics of the motorcycle, we can note a number of other positive details. For example, the engine had an excellent compression ratio at that time, which was 9.3. To accelerate as smoothly and comfortably as possible, engineers installed a manual gearbox at 4 speeds.
The first modification immediately received positive reviews; the Java 250 design and strong components made it possible to use the initial production technology in subsequent modifications, so only small elements were further modified. Soon a modification appeared with a modified angle of the box and engine. Manufacturers claim that this has made the engine more powerful and reliable. Today, it is quite difficult to find spare parts for the Java 250 ; there are not as many owners of this motorcycle in Russia as we would like, so you can only buy used spare parts.
Also today in the motorcycle markets you can find a new motorcycle called “Java 250”, but now this is not the same Java at all - the new items are positioned as off-road or cross-country versions. Buying a working Java 250 in good condition will be quite problematic. If you find someone who wants to sell a motorcycle, be prepared to pay from 30 to 100 thousand rubles for it; the model now costs a lot of money. And if you find such a model, be sure to sell it or restore it; the driving pleasure will be unsurpassed even today. And the appearance will be the envy of other modern representatives of similar motorcycles.
tuning Java 250
Despite their service life of approximately 30 years, today's old ladies can compete with other motorcycles of the Soviet Union, such as the new Ural, old Minsk or Dnepr motorcycles. Often the motorcycle is liked by experienced bikers and those who have already experienced its power and excellent characteristics.
Exhaust system improvement
Another significant thing in tuning the Java 350 is the exhaust system. Unlike a 4-stroke engine, in a 2-stroke engine the cylinder is filled by purging the cylinder. With a properly assembled resonator, a fresh fuel mixture effectively fills the cylinder, and due to the conicity of the resonator, the sound wave is reflected. Thus, part of the mixture does not fly out into the pipe, but returning to the cylinder gives up to 20% more power. You can weld such a resonator with your own hands from sheet steel 0.6-0.8 mm thick, and argon or semi-automatic welding is recommended. The exhaust pipe of the resonator can be made by shortening the standard one by increasing the cone according to the drawing:
According to the figure, the engine will have a sharp pickup and increase in power around 5000 rpm. The damping nozzle is not necessary and only performs a noise-absorbing function. As with tuning the Voskhod motorcycle, this resonator can be used in the same way.
The significant mass of the crankshaft has high inertia, which is done for smooth operation of the engine. By lightening it, you can achieve a sharp response to gas and improved acceleration dynamics. Keep in mind that with this modification of the engine, it is extremely reluctant to operate at idle and low speeds. And of course, don’t forget about replacing the ignition from a contact system to an electronic microprocessor system.
Body and frame tuning
Its appearance will largely depend on how the frame base on the motorcycle is redone. At the present stage, there are several popular ways to remake the Dnepr frame.
Regardless of the modification of this bike, all models have a similar frame design.
You can extend the frame at the rear of the motorcycle. This tuning involves adding 15-20 centimeters to the frame, which increases the space for the rider’s legs. When the frame is lengthened, the driveshaft also lengthens, and the adjustment of the distance by which the frame should be lengthened depends on the height of the driver. If you lengthen the frame in the front part, you can achieve a landing similar to classic American choppers, while you do not need to change the driveshaft, but you will have to redo the pedal arrangement.
The frame is also expanded. We are talking about installing a more powerful rear wheel. To do this, an additional gearbox is installed on the cardan shaft, which will shift the cardan output to the side. It is best to install wheels with a profile of 130-150 millimeters, this way you can achieve optimal ride quality from the bike. A tire that is too wide can add certain difficulties to the driver.
When changing the angle of the front fork, experts recommend increasing the angle of inclination by no more than 35 degrees, otherwise the handling of the motorcycle will be seriously affected. In addition, an increase in the angle of inclination is accompanied by loads on the “stays” of the front fork, which leads to their rapid wear and failure.
Changing the angle of the rear shock absorbers will provide a more aesthetically pleasing appearance for the motorcycle, however, as with the front forks, too much angle can result in a loss of load-carrying capacity to the point where even single-passenger riding becomes impossible.
Java engine tuning
First of all, I would like to talk about modernizing the engine of this once legendary bike. The latter is done quite easily and quickly these days. The method of strengthening the power unit, given to us by our parents, will remain virtually unchanged. These motorcycles are quite easy to boost.
Tuning Java often involves adding another carburetor to the engine. In this case, the mounting of the basic fuel regulator is subject to change. A carburetor is installed on each cylinder only after a new mount (adapter) is installed on each “pot”. All this is mounted on pins - there is no need to invent anything new, as you can see for yourself. Each carburetor needs a separate filter. Buying a faucet for a tank with a couple of outlets is also not difficult.
Firstly, you need to adjust the purge channels for tuning the Java 350. In addition, the main goal of upgrading the Java engine is to increase the compression ratio. This way you can certainly supplement the power of the bike. All this won't cost that much. If you do not have the necessary tools and equipment for speeding up, you can turn to a turner. Even in small towns, such specialists are present, for which we must thank, first of all, the Soviet government, which relied on the engineering and mechanical potential of the labor resources of the USSR. There are many machines left on post-Soviet soil that are quite suitable for reducing the combustion chamber.
Do not forget that any changes to the combustion chamber, as well as the cylinder windows, must be carried out with the utmost care. Any mistake, in this case, can render the rather fragile duralumin “pots” unusable once and for all.
You will probably find photos of bikes after some of the above modifications here too.
What else can be improved?
Some owners improve the exhaust system of the Java motorcycle. Tuning, the photo of which is presented below, is performed by installing direct flows from the mufflers of VAZ cars. The pipe leading to the engine is cut fifty millimeters from the muffler itself, and the outer part is bent at a certain angle. To connect to the elbow, the pipe is cut and installed securely. First, body clamps are welded into the forward flow, and a kickstand is installed on the bike.
The tachometer taken from the VAZ-2106 adds additional aggressiveness and presentability to the two-wheeled unit. It is connected identically to the connection diagram in the car. To install a new starter on a Java, you will need to replace the flywheel, install an additional housing mount and a reinforced battery.
A good innovation would be to change the lighting of the motorcycle. You can choose LEDs to match the color of the unit or play with contrast. The lighting of the rims, exhaust pipe, engine and other main components of the device will look original.
In conclusion
To improve the performance of their two-wheeled “iron horse” and give it a second life, many owners use tuning. “Java 350” is a quite decent motorcycle, but in design and parameters it no longer reaches modern models. Modernization allows you to make fundamental changes to the design, resulting in a car whose owner will be the envy of everyone around you.
It is quite possible to remake the equipment yourself. Properly performed restyling will not only transform the motorcycle, but also make it a unique bike. The main thing is to stock up on the necessary materials, theoretical knowledge and patience.
Previous entry Motorcycle repair and maintenance
Features of electrical equipment
In many respects, the components and assemblies of the Czech motorcycle were similar to domestic products, but at the same time they differed:
- high quality;
- amazing wear resistance;
- maintainability and long service life.
In those years, Java motorcycles were in short supply, so they were often sold second-hand. And at the same time, the price remained quite high. New owners could immediately get behind the wheel and operate the equipment without any restrictions, because:
- wiring to Java did not require maintenance;
- the engine had a significant service life;
- shock absorbers and suspension had a fairly high safety margin;
- consumables were required no more often than provided for by the technical regulations.
Repair instructions for Java motorcycles officially supplied to the USSR
However, the manufacturer constantly modernized its motorcycle models, and each time made changes to components and assemblies. In particular, in different years the following were supplied to the territory of the USSR:
- model 559-07 was produced since 1969 under the name “JAWA 250” and was a variant with a 250 cc engine producing 12 hp. with 6V equipment;
- model 634 (01-04) was produced from 1973 under the name “JAWA 350” and represented a variant with an increase to 350 cc. cm 16 hp motor, designed to work with 6V equipment;
- model 634 (01-08) was produced since 1977 under the name “JAWA 350”, but already with 12-volt equipment and on 16-inch wheels;
- Model 638 has been produced since 1986 under the name "JAWA 350". It had only visual differences in the shape of the frame and was equipped with 18-inch wheels (see wiring diagram for Java 638);
- Model 640 was the last modification that was officially supplied to our country. It was also designed to operate 12-volt equipment and had differences in design and suspension.
Original wiring diagram for Java 12V model 638
Equipment 6W
For the first 8 years of deliveries from Czechoslovakia, JAWA motorcycles were equipped with equipment designed for a current of 6V.
Original color diagram of electrical equipment Java model 634
There are differences in the above diagram due to modification. In particular, the JAWA 634.8.00 model does not have:
- direction indicator warning lamp;
- neutral control lamp in the gearbox;
- breaker capacitors.
Subsequent motorcycles had these electrical parts installed at the factory. And domestic craftsmen independently equipped their “iron horses” using a new scheme.
Differences in voltage were not an obstacle for owners, who often independently converted the motorcycle’s power supply from 6V to 12V. This required:
- replace the generator with a new six-pole one with a self-excitation system of electric current, which made it possible to operate the motorcycle with a completely discharged battery;
- replace incandescent lamps with more powerful ones;
- install contactless electronic ignition;
- replace high voltage wires.
Equipment 12W
Later, the manufacturer recognized the promise of 12-volt equipment and began to equip its products with it. Thereby:
- electronic ignition appeared on motorcycles;
- changing the generator circuit made it possible to operate the vehicle without a battery (during the daytime);
- The luminous flux of the headlights has increased and the brightness of the side lights has increased.
Original photo of the electrical circuit of the model 640 in Czech.
Features of the 12-volt equipment include a bipolar turn relay, which has not previously been found on motorcycles. Its operation scheme is based on the principle of the difference in the current consumption of the control lamp (6W) and the direction indicator lamps (21W):
when turning on the right turn, “+” from the generator or battery enters the right turn circuit, passing through the terminals of the bipolar relay;
- in this case, current is supplied to the right front and rear right turn signal lamps;
- The indicator lamp is directly connected with one contact to the right turn circuit, and the other to the left turn circuit. When the right turn is turned on, “+” is supplied to the control lamp, and “-” appears in the left circuit of the control lamp for the other contact, coming through the filament of the left lamp of the turn circuit (see also the Java 350 wiring diagram).
Unusual yellow Java 638
Personally, I have a conflicting opinion. It is clear that the author of this project spent a lot of time on its implementation. Didn't save money, bought an exhaust with resonators
, painted the entire motorcycle in a bright and noticeable color, installed caps on the wheels. I even installed a mono shock absorber.
With all this, I have one question: why? It’s not clear why the “tail” of the motorcycle should be lifted up so much, or why install clip-ons. I think this bike will be equally “comfortable!”
both driver and passenger.
Looking at the passenger footrests, it’s difficult to imagine how two people would sit on this Java. Well, the final chord – turquoise zero
!
Of course, the author is a great fellow
, had a hand in it, but the essence of the project remains a mystery to me.
Perhaps, such Java is truly the only one in the world!
Here I can definitely say that I would like this “tuning”
did not engage in training under any circumstances. I had enough sad experiences with vinyl film, but this is still on a completely different level.
I can’t say that this solution looks beautiful, nor can I imagine what will happen to all these “carpets” after a trip in the rain.
I would put such a motorcycle at home to entertain guests, but, alas, there is no extra space. It’s strange or not that here the author of the project decided to abandon the standard steering wheel
? Who knows, maybe the motorcycle really went faster or the landing became more comfortable.
Extraordinary JAWA tuning in action!
Here, too, I simply have no words. On the one hand, most of the motorcycle is kept original - the lower part. The pipes are shiny, no oil is leaking from them, good tires are installed, the engine is clean
. Most likely, technically everything is fine with this motorcycle, but why “decorate” it like that?
I remember as a child I was perplexed when I saw motorcycles passing by, whose seats were covered with some kind of skin, carpet, fur coat or something like that. Is this really convenient?
What's wrong with standard casing? Even if it was in short supply, is it really impossible to use another, more suitable material?
Well, I’m generally silent about the fairing. The solution with lighting devices is strange, in my opinion. At the very least, very extraordinary. And yet it is not clear why he was wrapped in a rag. Probably to match the seat.
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