Kick start is a method of starting an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

(usually that of a

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

) by pushing a

ratchet Ratchet may refer to: Devices * Ratchet (device), a mechanical device that allows movement in only one direction * Ratchet, metonomic name for a socket wrench incorporating a ratcheting device * Ratchet (instrument), a music instrument and a ...

ing lever with one's foot. Kick start mechanisms were almost universally a part of motorcycle engines before the mid-1970s, and were phased out of production over the next twenty years or so as

electric starter A starter (also self-starter, cranking motor, or starter motor) is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. T ...

s became standard equipment. There are still some motorcycles produced that have both kick and electric starters. Many

moped A moped ( ) is a type of small motorcycle, generally having a less stringent licensing requirement than full motorcycles or automobiles. The term used to mean a similar vehicle except with both bicycle pedals and a motorcycle engine. Mopeds typ ...

s and scooters also carry both a kick start and an electric start, the former being useful in case the latter fails, as scooter and moped batteries tend to be smaller and, as a result, run down much faster than other forms of automotive batteries. Also, it is usually not possible to

push start Push starting, also known as bump starting, roll starting, clutch starting, popping the clutch or crash starting, is a method of starting a motor vehicle with an internal combustion engine and with a manual transmission and with a mechanical fuel ...

a moped or scooter with

automatic transmission An automatic transmission (sometimes abbreviated to auto or AT) is a multi-speed transmission used in internal combustion engine-based motor vehicles that does not require any input from the driver to change forward gears under normal driving ...

. Larger motorcycles featured a manual

compression release A compression release mechanism works to ease the starting of internal combustion engines by allowing them to spin up to starting speed without having to work against the pumping action of the pistons. It does this through a release valve that is i ...

mechanism that made starting easier while modern units did this automatically through a cable attached to the kick start lever. Today, dedicated off-road motorcycles and many ATVs use kick start systems, to avoid the weight of electric starters. The majority of the inexpensive two-wheelers and sometimes three-wheelers in developing countries, also use kick start systems.

Operation

Before starting, kickstart levers are generally unfolded from the side of the motorcycle so that the rider can clear the side of the engine as it rotates. As the lever begins to descend under the riders foot, the rachet engages a gear linked to the crankshaft causing it to spin past

top dead center In a reciprocating engine, the dead centre is the position of a piston in which it is either farthest from, or nearest to, the crankshaft. The former is known as Top Dead Centre (TDC) while the latter is known as Bottom Dead Centre (BDC). ...

so that an ignition spark can ignite the compressed fuel mixture. Upon starting, the rachet disengages and the rider folds the lever back. On some large displacement twins or singles, 'kickback' can occur if the fuel ignites before the piston reaches top dead center. This causes the crank to spin backwards and can be painful for the rider as the lever kicks back on their foot. The first kick start motorcycle was a British Scott Motorcycle two-stroke twin manufactured in 1910. Some scooters have kick starters with a tendency not to always work, if not performed correctly. Some manufacturers have also included kick starters in their models, only for a purpose of introducing apparent convenience for ignition, as opposed to offering a reliable alternative for an electric starter.

References

{{DEFAULTSORT:Kick Start Motorcycle engines Starting systems

Operation

See also

References