You will need
- - the engine "Minsk" M-105, M-106 or M-125;
- - mechanical workshop;
- - rings and seals crank chamber;
- - carburetor K-36И;
- - magnetos M-24G;
- - spark plug PAL-14-8 or BOSH-260-280
If you choose the base engine, prefer M-125. Compared with previous models M-105 and M-106, it has better cooling, which increases its force for sporting purposes. If for model M-105 and M-106 the power of 9 HP is almost the limit, for the model M-125 can be achieved 10,3-10,8 HP in the average machine shop. The engine should be well run and have serviceable parts and mechanisms.
Completely disassemble the engine. In both halves of the crankcase, insert and secure the rings which will reduce the diameter of the crank camera to 121 mm. Change the oil seals of the crank camera on a specially designed sports model. They must withstand a pressure of at least 0.8 kg/sq cm Change timing: phase of the release must be equal to 164 degrees, the phase of the purge – 108 degrees, the phase of issue – 128 degrees.
Instead of the standard, set the carb-TO-36И with a cone diameter 27 mm. Its main fuel jet needs to have a capacity of not less than 0.25 l/min inlet ports in the piston sawed to 25 mm so that they coincide with the vent Windows on the cylinder of the motor.
The intake manifold will extend to 300 mm. the length of the intake tube from the bore to the carb must be 100 mm, the inner diameter of the intake manifold needs to be 40 mm, the length of the manifold from the carb to the air filter – 150 mm. the ignition system set magneto M-24G. The ignition timing set at the level of 2.2-2.5 mm before TDC. Screw candle type PAL-14-8 or BOSH-260-280.
Bronze separator-connecting rod crankshaft replace the duralumin type D-16T or-95. Also suitable homemade cieniowane steel or steel of grade 45 without heat treatment with the obligatory silver of the surface.
Conduct additional polishing of the channels of the barrel, check and adjust, if necessary, the cross section of these channels, as well as the angles of the exit purge. Factory level processing of these surfaces is not sufficient for sporting purposes.
Air filter replace larger, with a tank capacity of not less than 3 years and paper filter elements. After running forced so motor install the carb with a 28mm diffuser, the length of the tube from the bore to the center of the spray increase up to 135 mm, the length of the manifold from the carb to the air filter, increase up to 170 mm.
Forced in this way the engine use gasoline grades B-95, B-100 or A-98. Motor oil MS-20 in a ratio of 1:20. To further enhance the power you will need to install the sports of the crankshaft, piston and piston rings, the transition to a higher timing, and application racing muffler and carb.