In detail: do-it-yourself Java 350 repair from a real master for the site my.housecope.com.
The legendary Java 350 motorcycle is the dream of every motorcyclist of the late 20th century. No Soviet motorcycle could match Java's workmanship and ride quality. The particular popularity of Czechoslovak technology is still relevant today. Naturally, every owner wants to improve the characteristics of the model, and the topic of today's article is Java tuning. In it, we will look at what tuning Java 638 is, how to achieve the best return from the engine and create a modern appearance with our own hands. We will find out how the Java 634 tuning differs from the 638 model and which one is better.
The power system is very important for a two-stroke motorcycle. The filling of the cylinders and the power depend on the quality of mixing fuel with air. And also the petal valves play a huge role in this system. It allows the fuel mixture to be admitted when the piston is sucked in, and does not allow the mixture to be pushed back, thereby improving the operation of the engine. The petal valves can be picked up from any other two-stroke motorcycle of similar cubic capacity. A photo example is given below:
The efficiency of tuning Java 638 can be significantly increased by dividing the intake ports into two separate ones for your carburetor for each cylinder.
One regular carburetor is not able to fully cope with its task and significantly chokes the engine in terms of speed. Fitting a Mikuni or Keihin crossover carburetor with a 28mm diffuser will drastically change the behavior of the motor. And how to tune the Java carburetor, you can read here.
Another big thing about tuning the Java 350 is the exhaust system. Unlike a 4-stroke engine, a 2-stroke cylinder is filled by blowing out the cylinder. With a properly assembled resonator, a fresh mixture of fuel effectively fills the cylinder, due to the taper 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 with a thickness of 0.6-0.8 mm, while argon or semi-automatic welding is recommended. The outlet pipe of the resonator can be made by shortening the standard by increasing the cone according to the drawing:
Video (click to play).
According to the figure, the engine will have a sharp pickup and a power increase in the region of 5000 rpm. At the same time, the muffler is optional and performs only 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 a large inertia, which is made for smooth engine operation. By lightening it, you can achieve a sharp reaction to the gas, and improve the acceleration dynamics. Keep in mind that with this modification of the engine, it is extremely reluctant to work at idle and low speeds. And of course, do not forget about replacing the ignition from the contact system with an electronic microprocessor one.
Think about safety first. Standard rims, and even more so drum brakes, are not able to cope with the increased power. It is recommended to install a good disc brake together with replacing spoked rims with alloy discs. This will not only give your bike a modern look, but it will also dramatically improve trail stability. Accordingly, the improved rims from another motorcycle are designed for more braking force and have a normal mount under the brake disc. Good road tires are also a must.
Replacing the headlight and the rest of the outdated lighting equipment will be to everyone's taste. And the dashboard is easy to transform by installing LED strip lighting.
The standard steering wheel can be easily replaced with clip-ons, or a straight-shaped steering wheel, which will slightly improve the driver's aerodynamics due to an inclined landing. Installing visors is no longer in vogue, as in Soviet times, they create too much air resistance in front of them. Much preferable is a sports body kit, which, depending on the financial investment, can be picked up from any other motorcycle, but if you want to make it yourself from fiberglass and epoxy resin. Tuning of the Java motorcycle in the photo:
And finally, we want to say that a boosted engine requires good 2-stroke oil and timely maintenance. Java tuning is a fun activity that requires imagination and straight arms. Subject to the tuning technology, the result will not leave you indifferent
JAWA motorcycles are long-established bikes. Their reliability and efficiency still attracts the attention of motorists. The unpretentiousness of climatic conditions and excellent cross-country ability on any road surface makes JAVU an excellent alternative to a car to this day.
The power of the JAWA 350 engine is 27 horsepower, accelerating the bike to 125 km / h. At the same time, gasoline consumption is very low: only 4-5 liters per 100 kilometers.
A feature of the motorcycle is the ability to transport two people at the same time due to the wide saddle. The JAWA has a very solid construction and balance that makes the dynamics very enjoyable for both urban and rural driving.
The volume of the JAWA 350 engine is only 343 cm3. Moreover, it has 2 cylinders and two strokes. For such a small volume, the bike delivers good performance. This makes it an excellent transport for both young people and avid motorists.
Considering that JAWA was assembled in Soviet times at a plant in Prague, it is very hardy and rarely creates problems... However, problems do occur. So, for example, during long-term operation, there is a high probability of a problem with the ignition system. It would be best to change it to contactless, from Japanese manufacturers.
Oil leaks often occur, so the motor will have to be overhauled to seal the cracks. Dismantling the JAWA 350 engine is not much different from Soviet-made motorcycles. Everything is quite simple and straightforward, it is easy to do it yourself at home. Even the order of assembly will not take much of your time and effort.
