Many people want to become motor sportsmen, but not all beginners have enough money to purchase a ready-made sports bike. There is only one way out in this situation - to independently prepare a standard car. The Minsk engine is considered to be one of the simplest in design and can be easily boosted. It should be borne in mind that in this case, the resource of the motor decreases in proportion to the increase in power.
It is necessary
- - engine "Minsk" M-105, M-106 or M-125;
- - mechanical workshop;
- - rings and oil seals of the crank chamber;
- - carburetor K-36I;
- - magneto M-24G;
- - spark plug PAL-14-8 or BOSH-260-280
Instructions
Step 1
If you choose the base engine, give preference to the M-125. Compared with the previous models M-105 and M-106, it has improved cooling, which increases the possibility of forcing it for sports purposes. If for the M-105 and M-106 models the power is 9 hp. is almost the limit, then for the M-125 model you can achieve 10, 3-10, 8 hp. in an average mechanical workshop. The engine must be well run in and have serviceable parts and mechanisms.
Step 2
Disassemble the engine completely. Insert and securely fasten rings in both halves of the crankcase, which will reduce the diameter of the crank chamber to 121 mm. Change the crankcase oil seals to specially designed sport models. They must necessarily withstand a pressure of at least 0.8 kg / sq. Cm. Change the valve timing: the exhaust phase should be 164 degrees, the purge phase should be 108 degrees, the exhaust phase should be 128 degrees.
Step 3
Instead of the standard one, install a K-36I carburetor with a 27 mm diffuser diameter. Its main fuel jet must have a flow capacity of at least 0.25 l / min. Cut the blow-out holes in the piston up to 25 mm so that they coincide with the blow-out holes on the motor cylinder.
Step 4
Extend the intake manifold up to 300 mm. In this case, the length of the intake pipe from the cylinder mirror to the carburetor should be 100 mm, the inner 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 magneto M-24G in the ignition system. Set the ignition timing to a level of 2, 2-2, 5 mm to TDC. Screw in a PAL-14-8 or BOSH-260-280 plug.
Step 5
Replace the bronze separator of the lower head of the crankshaft connecting rod with a duralumin type D-16T or B-95. Also homemade from cyanide steel or steel grade 45 without heat treatment with the obligatory silvering of the surface is also suitable.
Step 6
Carry out additional polishing of the cylinder bores, 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.
Step 7
Replace the air filter with a larger one with a tank volume of at least 3 liters and paper filter elements. After running the engine boosted in this way, install a carburetor with a 28 mm diffuser, increase the length of the branch pipe from the cylinder mirror to the center of the atomizer to 135 mm, and increase the length of the manifold from the carburetor to the air filter to 170 mm.
Step 8
In an engine boosted in this way, use gasoline of the B-95, B-100 or A-98 brands. Engine oil - MC-20 in a ratio of 1:20. Further increase in power will require the installation of a sports crankshaft, piston and piston rings, a transition to higher valve timing, as well as the use of a racing muffler and carburetor.
