Many people want to become motorcyclists, but not all beginners have enough money to purchase a ready-made sports motorcycle. There is only one way out in this situation - to prepare a standard car yourself. The Minsk engine is considered one of the simplest in design and can easily be slightly boosted. It should be taken into account that in this case the engine resource decreases in proportion to the increase in power.
How to boost a Minsk go-kart engine
Many people want to become motorcyclists, but not all beginners have enough money to purchase a ready-made sports motorcycle. There is only one way out in this situation - to prepare a standard car yourself. The Minsk engine is considered one of the simplest in design and can easily be slightly boosted. It should be taken into account that in this case the engine resource decreases in proportion to the increase in power.
Exhaust system
This element must be modified if the engine has been tuned. The problem arises due to the fact that the standard muffler is not designed for increased exhaust gas pressure.
As a result, in certain operating modes, the motorcycle engine begins to choke. Optimal mufflers were installed on a motocross motorcycle, but it is now almost impossible to purchase such a part. Such versions have not been produced for more than 20 years, and therefore spare parts for them have not been produced either.
You can make a high-quality muffler yourself. To understand how to make it yourself, let's look at how it works. Using a muffler of a certain shape allows you to create reverse draft. It allows the remaining combustible mixture to be sucked into the engine. A resonator is used for this.
You can make this detail yourself. On the Internet you can find a large number of formulas by which calculations are made. It is important to remember the basic rule - the size of the resonator directly depends on the power of the motor. This kind of motorcycle tuning in Minsk allows you to achieve maximum efficiency and engine response.
Instructions
If you're choosing a base engine, go for the M-125. Compared to the previous models M-105 and M-106, it has improved cooling, which increases the possibility of boosting it for sports purposes. If for models M-105 and M-106 the power is 9 hp. is almost the maximum, then for the M-125 model you can achieve 10.3-10.8 hp. in the conditions of an average mechanical workshop. The engine must be well run-in and have serviceable parts and mechanisms.
Completely disassemble the engine. Insert and securely fasten rings into both halves of the crankcase, which will reduce the diameter of the crank chamber to 121 mm. Replace your crank chamber seals with specially designed sport models. They must withstand pressure of at least 0.8 kg/sq.cm. Change the valve timing: exhaust phase should be 164 degrees, scavenging phase should be 108 degrees, exhaust phase should be 128 degrees.
Instead of the standard one, install a K-36I carburetor with a diffuser diameter of 27 mm. Its main fuel jet must have a flow rate of at least 0.25 l/min. Cut the purge windows in the piston to 25 mm so that they coincide with the purge windows on the motor cylinder.
Extend the intake manifold to 300 mm. In this case, the length of the intake pipe from the cylinder mirror to the carburetor should be 100 mm, the internal diameter of the intake manifold should be 40 mm, the length of the manifold from the carburetor to the air filter should be 150 mm. Install an M-24G magneto in the ignition system. Set the ignition timing to 2.2-2.5 mm before TDC. Screw in a spark plug type PAL-14-8 or BOSCH-260-280.
Replace the bronze separator of the lower head of the crankshaft connecting rod with an alloy type D-16T or V-95. A homemade one made from cyanidated steel or grade 45 steel without heat treatment with mandatory silvering of the surface is also suitable.
Carry out additional polishing of the cylinder channels, check and correct, if necessary, the cross-section of these channels, as well as the angles of the purge outlet. The factory level of processing of these surfaces is insufficient for sports purposes.
Replace the air filter with a larger one, with a reservoir volume of at least 3 liters and paper filter elements. After running in the engine boosted in this way, install a carburetor with a 28 mm diffuser, increase the length of the pipe from the cylinder mirror to the center of the nozzle to 135 mm, increase the length of the manifold from the carburetor to the air filter to 170 mm.
In an engine boosted in this way, use B-95, B-100 or A-98 gasoline. Motor oil - MS-20 in a ratio of 1:20. To further increase power, you will need to install a sports crankshaft, piston and piston rings, switch to higher valve timing, as well as use a racing muffler and carburetor.
Source
Improving the quality of the air-fuel mixture
The formation of the air-fuel mixture in this vehicle occurs in the carburetor. To reduce losses, at this stage the jets and diffuser surface are polished. This kind of tuning of the Minsk motorcycle can be done with your own hands using thick, rigid thread and Goi paste. The amount of fuel mixture entering the cylinder depends on the diameter of the diffuser.
A significant increase in maximum speed can only be achieved by replacing the carburetor. In the 90s, Japanese carburetors, produced at that time in India, were installed on the Minsk. With proper adjustment, the motorcycle accelerated more dynamically and had greater traction at low speeds.
When setting up a carburetor, the parameters specified in the instructions should serve only as a starting point, but not as reference values. Any carburetor is customizable. An important detail is the tightness of the contacting planes: the carburetor and the adapter. The tightness of the connection significantly affects the life of the engine.
How to boost a Minsk go-kart engine
Every year the army of motorcyclists is replenished with newcomers. But not everyone who wants to can get into a sports car right away - there are often not enough of them in clubs. Meanwhile, there is a way out - remaking road motorcycles. Many people do this. Reconstruction of the chassis usually does not cause difficulties. It is more difficult with an engine, in which you have to make changes that require certain qualifications. To help young athletes, today we are publishing materials on boosting road engines for cars - 125 cm3. They are designed not only for motorcyclists, but also for karting drivers. It should be borne in mind that the service life of the engine after modification decreases almost in proportion to the degree of boost.
Nine horsepower!
Until recently, this power for the 125 cc Minsk M-105 engine was almost maximum, but now it is possessed by the new production M-106 engines installed on road motorcycles. Thanks to a significant increase in the number and area of fins on the cylinder and head, cooling has improved and it has become possible to further boost the engine for sports purposes.
We will tell you about the simplest forcing option. allowing to reach 10.3-10.8 liters. With. at 5700 - 6200 rpm. It is designed primarily for that rather significant group of racers who are only taking their first steps in the sport and do not have much experience in preparing cars or equipment other than what can be found in an average mechanic workshop.
How to force Minsk
The engine of the Minsk is accessible for independent boosting. At the same time, it not only increases power to 15 hp, but also becomes more economical, and if the work is done carefully, it is also more durable.
Instructions
1. Determine the condition of the motor. The perfect option would be the latest and tested one. If the initial engine is dilapidated, purchase new crankshaft, piston with rings, bearings, cuffs and get ready for careful work. First of all, completely disassemble the power apparatus into its components.
2. Make sure that the windows in the liner match the channels in the cylinder jacket by removing metal. At the same time, make sure that the thickness of the walls of the crankcase jacket and neck remains at least 3 mm. To process the canals, use a drill with a set of cutters and scrapers. Achieve symmetry and high cleanliness of the surface of the purge channels. If after treatment the surface of the canals becomes smooth in appearance and to the touch, there is no need to polish it. Be sure to keep the height of the upper bypass windows and the vertical blowing angle constant. Make the front edge of the bypass window sharp, and saw off the upper and lower edges of the upper bleeder window along a radius equal to the thickness of the sleeve.
3. Check that the cylinder skirt fits freely into the crankcase assembled without a gasket. If necessary, remove unnecessary metal from the crankcase neck. Adjust the bypass channels between the jacket and the crankcase according to a pattern that repeats the silhouette of the bypass channels of the jacket. The sleeve skirt should not block the bypass channels. If there is overlap, remove the jumper and adjust the windows in the sleeve to match the windows in the crankcase. Borrow the inlet window so that a smooth and stepless transition is formed from a round diffuser to a rectangular diffuser, with curves to the outlet window.
4. Align the exhaust channel perfectly and be sure to polish it. File the top and bottom edges of the window to give it an oval shape. Bevel the outlet and top bypass ports. Also chamfer the piston rings and coat the rings themselves with matte chrome. File the gap in the ring lock to 0.2-0.3 mm. Treat the surface of the cylinder liner by grinding, honing or lapping. Bring the gap between the piston skirt and the cylinder mirror to 0.04-0.05 mm.
5. Process the windows in the piston skirt so that they match the windows in the liner skirt. Round the edges on the piston skirt with a radius of 0.5 mm. Polish the piston skirt itself. At bottom dead center, the piston should not cover the lower edge of the upper bypass port. To do this, either remove the flats or grind the piston head along a radius of 70 mm to the required amount. Leave the piston bottom no thinner than 5 mm. Mill the ends of the connecting rod bosses so that their dimensions do not differ by more than 0.1 mm. Lighten the piston pin by cutting it under the cone, protecting its working surface from damage.
6. Check the radial clearances in the upper and lower connecting rod bearings. They must be no more than 8 microns (upper) and 12 microns (lower). If the gaps are larger than these values, replace the crankshaft with a new one. Press out the crankshaft pins separately from each cheek. Plug the standard balancing holes with aluminum, and compensate for its weight with lead plugs inserted into the lower parts of the crankshaft cheeks. Grind the cheeks themselves to a diameter of 100 mm, avoiding damage to the trunnions. Reduce the diameter of the trunnions themselves to 17 mm using fine sanding paper.
7. Achieve smooth mating of all surfaces of the connecting rod, avoiding marks on the joints. Be sure to polish the outer surface of the connecting rod. Before assembling the crankshaft, rub molybdenum disulfide on all parts of the connecting rod lower bearing. Press the crank pin without distortion. In this case, the axial clearance between the lower head of the connecting rod and the cheek should be 1.6-1.7 mm. Carefully center and balance the crankshaft.
8. Grind the surface of the crankcase chamber clean. Secure the aluminum rings with epoxy glue and 3 M5 countersunk screws. Fill all gaps in the crank chamber with epoxy resin filled with aluminum powder or with a plasticizer. After processing, assemble the crankcase using sealant without gasket. When installing the crankshaft, secure it against longitudinal displacement with two washers. Assemble all motor threaded connections using anaerobic sealant.
Modification of a standard cylinder
The best solution is tuning the Minsk 125 motorcycle with modifications to its standard cylinder. First of all, it is necessary to eliminate possible displacements of the purge and bypass windows. The purging of the fuel mixture in a two-stroke engine depends on their correct position, which directly affects the acceleration dynamics, efficiency and top speed. To do this, excess metal is removed from the liner, previously removed from the cylinder, using a mechanical or hand tool. All work involves raising the window by 2 mm, boring the radius of the curves and rounding the sharp edges. Such internal tuning of the Minsk motorcycle can increase the number of maximum revolutions by 1000.
Read also: GOST R 51778 2001
Tip 2: How to boost a motorcycle engine
Instructions
1. Before boosting any engine, remove the installed power limiter. Without this, the forcing process loses every sense. Often, instead of a power limiter, a maximum cycle limiter is installed. Remove that too. After boosting the engine, most likely, the engine will develop maximum power and torque at higher cycles.
2. Chip tuning is the reprogramming of the engine control system so that it develops higher performance. In practice, everything looks simpler: to force it, the injection control unit is changed. To do this independently does not require extensive knowledge. Buy such a block for your motorcycle at a motorcycle store that sells tuning kits. Installation instructions will be included with the product. This boost method is extremely suitable for modern foreign-made motorcycles.
Tip 3: How to boost the Minsk engine
Many people want to become motorcyclists, but not every beginner has enough money to buy a ready-made sports motorcycle. There is only one way out in such a situation - to prepare a standard car yourself. The Minsk engine is considered one of the most primitive in design and can be easily boosted. It should be considered that in this case the motor source decreases in proportion to the increase in power.
You will need
