How A Motorcycle Works – The Basics

Motorcycles of today are the true marvels of engineering a basic model of inner parts of a typical motorcycle is shown here in this article we will explain the basic function of each of these parts in a motorcycle let’s begin from.

How a motorcycle engine starts

All motorcycles have either a Kick-starter or a self-starter or both a Kick-starter mechanism is simple yet interesting as the Kick-starter lever is descended a helical spline force. The gear to slide and engage with a freewheeling gear on the main shaft as the lever is descended further

The gear spins on its axis and transfers the power to the clutch hub. Then the clutch hub transfers the power to the crankshaft and eventually to the engine in a self-starter system.

A battery-powered motor provides initial spin to the engine once the engine is started. The starter motor has to be disengaged from the crankshaft to prevent damage due to excessive speed and this is achieved by using a one-way clutch.

The one-way clutch has an outer race and an inner race with small rollers as the starter motor spins the outer race in one direction. The rollers get trapped between the surfaces and the power is transferred to the inner race and thus to the crankshaft.

Once the inner race starts spinning faster than the outer race, the rollers get released causing the inner race to spin freely like every four-stroke gasoline engine. Motorcycle engines require a source of ignition to ignite the air fuel mixture.

For power strokes a spark plug is used for this purpose the spark plug requires voltage in excess of 20,000 volts to fire properly. In this particular model the voltage is obtained from the stator of the motorcycle although a 12-volt battery may be used for the same purpose.

The stator is a stationary coil of wires and the flywheel of the motorcycle has a set of permanent magnets which revolves around the stator and produces alternating current in the coils. Each output from the stator has different purposes.

Output for the ignition purpose is received from the exciter coil this coil has a denser winding of thinner wire than the other coils to produce higher voltage for the ignition this voltage is supplied to an electrical component known as the capacitive discharge ignition or CDI unit.

The primary function of the CDI unit is to store electric charge and dump the stored charge when required. A capacitor inside the CDI unit stores the electric charge another component known as a pickup coil tells the CDI unit when to dump this charge.

The pickup coil has small magnet with a coil of wire around it the flywheel has a small extrusion on its outer surface as this extrusion approaches and passes the pickup coil a small voltage is developed in the coil.

This voltage is supplied to the CDI unit which closes an electronic switch known as a silicon controlled rectifier or SCR this will dump all the charge from the capacitor through the output of the CDI unit to increase the voltage further an ignition coil is used the ignition coil is a step-up transformer which increases voltage up to 200 times the input voltage which is sufficient to fire the spark plug.

Several other factors contribute to the continuous operation of the engine. The exhaust valves are controlled by using a timing chain as shown here as long as the engine is running, the crankshaft rotates and transfers power to the other components for proper operation.

Single cylinder engines generally use a counterbalance to reduce the vibration caused by unbalanced forces the clutch helps in smooth transfer of power from the crankshaft to the transmission system helps in altering the speed and torque as per our requirement


This is the basis of all that you need to know about how a motorcycle works. We do hope that the information given will help you understand better on how a motorcycle works.


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