MAIN MOTORCYCLE COMPONENTS – Motorcycles, like cars and other power planes, need the power to move, fight air resistance, tire friction, and other obstacles. To enable a motorbike that we drive to move and go on the highway, the wheel of the motorcycle must have the power to move, and to drive it requires an engine.

A motorcycle that runs on a runway (lap) Engine is a device to generate power, it is referred to as the prime mover. So the engine here functions to change the heat energy from the combustion chamber into mechanical energy in the form of rotating power.

Power or power to drive the vehicle is obtained from the heat of combustion of fuel. So the heat that arises due to combustion is what is used to drive the vehicle, in other words, the pressure of the burning gas will cause rotation in the crank axis of the engine.


The main components of a motorcycle engine are:
1. Cylinder head

2. Cylinder block

3. Crankcase

So, the 3 main parts are the backbone for two-wheeled motor vehicles.

Today discuss: CYLINDER HEAD, CYLINDER BLOCK and PISTON (with full understanding)

1. Cylinder Head (Cylinder

The cylinder head rests on the top of the cylinder block. The fulcrum is sealed off with a gasket (gasket) to prevent compression leakage, besides that the metal surface of the cylinder head and the top surface of the cylinder block are not damaged. The cylinder head is usually made of aluminum alloy so that the rust-resistant is also resistant to high temperatures and light. Usually, the outside of the cylinder head construction is finned, this is to help release heat to the air-cooled engine.

2. Engine Cylinder Block

Cylinder liner and cylinder block are two parts that are attached to each other. The power of a motor is usually expressed by the size of the cylinder contents of a motor. The cylinder liner is firmly attached to the block, and the material is not the same. The cylinder liner is made of a material that is resistant to friction and heat, while the block is made of cast ironEach damage must be known to determine the repair steps. How to measure cylinder wear:
1. Remove the cylinder block

2. Remove the piston
3. Measure the diameter of the cylinder bore with the “dial indicator” part measured the top, middle, and bottom of the cylinder bore. Measurements were made twice in the crossed position.

Calculate the magnitude of ovality and gradient. Compare with the provisions in the service manual. If the magnitude of vileness and gradient exceeds the allowable limits, the cylinder bore must be oversized. Stages of oversize are 0.25 mm, 0.50 mm, 0.75 mm, and 1.00 mm. The first oversize should be 0.25 mm with wear below 0.25 mm and so on. If the cylinder is not possible to be oversized, the solution is to replace the cylinder lining.

Damages that occur in a two-step piston ring can result:
1. The inner cylinder wall wears out quickly

2. The engine is not stationary
3. The engine limps
4. The engine power is lowThe piston sizes for motorcycle use include:
5. + STD = Piston which is still original / new
6. Size + 0.25 mm = Piston oversize 25
7. Size 0.25 mm – Size 0.50 mm
8. Size 0.75 mm – Size 1.0 mm

The installation of the piston into the cylinder must pay attention to the signs that are there. The sign is usually in the form of arrows. The arrow must face the exhaust pipe (exhaust), if the piston installation is reversed then the result is very fatal, namely the wear that occurs between the cylinder wall with the piston side becomes very large. Another sign that must be considered is if we want to replace the piston, if the surface of the piston head is written a certain number, the number indicates that the cylinder diameter of the motorcycle has oversized. The replacement piston must be the same size as the cylinder or the piston being replaced.

In maintenance, the piston needs to be serviced, the treatment stages are:
1. The piston is released from the seat.

2. Soak the piston in cleaning fluid together with the piston rod, then dry. Clean the charcoal dirt in the piston ring groove.
3. Observe possible piston ring grooves. The greatest wear usually occurs in the compression ring groove.
4. Check the freedom of the piston ring groove with the feeler gauge. The piston ring groove can be improved by cutting a larger groove installing a steel ring on the top side.
5. Check for cracks in the piston. The smallest piston crack must be replaced.
6. Remove the piston pin. Before the piston pen is removed give a mark so that it is easily reassembled as before.
7. If the piston pin is a float type, remove the locking ring so that the pen is easily removed. Be careful when removing the ring, do not get damaged. Generally
the engine currently uses a pen that can move in the piston and is pressed on the piston rod.
8. After checking the piston pen, finish it again as before. Because the freedom of the pen against the piston is very small, ie between 0.005 to 0.0127 mm for pistons from aluminum, it is necessary to be installed carefully. Freedom on the piston rod that uses a slightly large width bearing which is around 0.0127 mm

Piston Step Movement To ensure that the engine continues to operate, the piston must always move continuously, the piston movement will stop at TDC (Top Dead Point) or in TMB (Bottom Dead Point). These two points are called dead centers. When the piston moves up, from TMB to TMA, or moves down from TMA to TMB, one single move from the piston is called “step”, the distance of movement of this piston is measured in mm.


Please enter your comment!
Please enter your name here