Dugald Clerk developed the first two cycle engine in 1879. It used a separate cylinder which functioned as a pump in order to transfer the fuel mixture to the cylinder.6
In 1899 John Day simplified Clerk's design into the type of 2 cycle engine that is very widely used today.13 Day cycle engines are crankcase scavenged and port timed. The crankcase and the part of the cylinder below the exhaust port is used as a pump. The operation of the Day cycle engine begins when the crankshaft is turned so that the piston moves from BDC upward (toward the head) creating a vacuum in the crankcase/cylinder area. The carburetor then feeds the fuel mixture into the crankcase through a reed valve or a rotary disk valve (driven by the engine). There are cast in ducts from the crankcase to the port in the cylinder to provide for intake and another from the exhausst port to the exhaust pipe. The height of the port in relationship to the length of the cylinder is called the "port timing."
On the first upstroke of the engine there would be no fuel inducted into the cylinder as the crankcase was empty. On the downstroke the piston now compresses the fuel mix, which has lubricated the piston in the cylinder and the bearings due to the fuel mix having oil added to it. As the piston moves downward is first uncovers the exhaust, but on the first stroke there is no burnt fuel to exhaust. As the piston moves downward further, it uncovers the intake port which has a duct that runs to the crankcase. Since the fuel mix in the crankcase is under pressure the mix moves through the duct and into the cylinder.
Because there is no obstruction in the cylinder of the fuel to move directly out of the exhaust port prior to the piston rising far enough to close the port, early engines used a high domed piston to slow down the flow of fuel. Later the fuel was "resonated" back into the cylinder using an expansion chamber design. When the piston rose close to TDC a spark ignites the fuel. As the piston is driven downward with power it first uncovers the exhaust port where the burned fuel is expelled under high pressure and then the intake port where the process has been completed and will keep repeating.
Later engines used a type of porting devised by the Deutz company to improve performance. It was called the Schnurle Reverse Flow system. DKW licensed this design for all their motorcycles. Their DKW RT 125 was one of the first motor vehicles to achieve over 100 mpg as a result.14
Vehicles for more people
Public transport is of utmost importance. You can quickly reach the first place, above all those who do not own a car. On the other hand, using the bus or smaller buses can get rid of the problem of parking the, which is often quite confusing for drivers. The bus ride makes it not need to be focused on driving. It is not surprising that this mode of transport is still often used on Polish roads. True, much of the buses is a machine that would give longer to the museum associated with the automotive industry, but there is also a really modern, rich in many of the features of vehicles on the road. The use of the exclusive bus is a feature of organized tours and I must admit that this is undoubtedly advantage of long journeys.
Lessons for motorcyclists
At least at the beginning of steering a motorcycle can give lessons to the student serving a practical course driving a lot of problems. Of course, as in the case of practical lessons on learning to drive car, also in this case we are dealing with the introduction of the student in handling motorcycle. More problems may occur already during city driving, at a later stage of practical lessons. This is due to the fact that the instructor and student are in different vehicles, usually a motorcyclist driving instructor in the car. Issuing commands and paying attention to mistakes so it can reach out to the student with some delay and it is the source of many problems.