Nuts and Bolts: A Beginner's Guide to Motorcycle Parts

Motorcycle ownership has many facets involved, from the point of purchasing your ride, to keeping up with the regular service required to keep it in top shape. To maintain your ride, it's essential to understand the intricacies of the machine. This comprehensive guide is designed to help you become more familiar with the major components of your motorcycle, in hopes to help you to understand its structure and functionality. If you're not mechanically inclined, however, we do always recommend having your ride checked out by a certified motorcycle mechanic near you rather than tackling issues yourself. Let's dive in!

a motorcycle mechanic works on a v-twin engine

Heart of the Beast: The Engine

The engine of a motorcycle is its lifeblood, controlling the transmission and vital processes to ensure the smooth operation of the bike. Its heart - the valve - permits air and fuel circulation, vital for combustion. Depending on the model, most commercial motorcycles run on conventional gasoline internal combustion engines, although electric and diesel engines also exist.

Motorcycle engines typically feature one to six cylinders, with the most prevalent configurations being single and twin, V-twin, opposite twin (or boxer), and in-line triple and in-line four. The number of cylinders impacts the ease of riding and maintenance: engines with more cylinders offer a smoother ride but are more complex and heavier, while engines with fewer cylinders have less power but are typically cheaper, lighter, and easier to maintain.

There are different types of cooling mechanisms employed by motorcycle engines:

  1. Liquid-cooled engines utilize a radiator to dissipate heat. Coolant circulates between the radiator and the cylinder to maintain temperature, giving these engines longer operating life and the ability to generate greater power.
  2. Air-cooled engines rely on air blowing over rear fins on the engine case to dissipitate heat. These engines are less mechanically complex, lighter, and cheaper, but have shorter operating lives due to expanding and contracting along a wide temperature range.

Motorcycles mainly feature either two-stroke or four-stroke engines:

  1. Two-stroke engines are lighter and simpler, producing more power when operating optimally. Modern two-strokes are usually single-cylinder, liquid-cooled, and under 600 cc.
  2. Four-stroke engines are cleaner and more reliable, providing power over a wider range of engine speeds.

Choking Up

A choke feature, exclusive to carbureted motorcycles, helps to adjust the amount of air entering the carburetor. This is essential during cold starts when the engine requires a richer air to fuel mixture.

Shifting Gears

A gear shifter is a control that adjusts the gears of the transmission up or down. Not all motorcycles, such as scooters and automatic models, have this feature. Gear shifting is sequential, meaning you need to go through each gear without skipping any. Always remember to leave your bike in neutral when stopping.

First person motorcycle view

The Frame: The Skeleton of the Motorcycle

The motorcycle frame serves as the vehicle's skeleton. It provides support to the engine and creates space for the steering and rear suspension while also supporting the rider, passengers, and baggage. Typically made of welded aluminum or alloy steel struts, more expensive motorcycle frames may feature carbon fiber, titanium, and magnesium.

Power Control: The Clutch Lever and Transmission

Most motorcycles utilize a sequential manual transmission, operated by a foot lever. This system requires rider input to change gears, but the clutch system is controlled and operated automatically. These systems are mostly found on small dirt bikes, many older mopeds and scooters, and various other motorcycles.

The clutch lever, located on the left handlebar, controls the power from the engine to the rear wheel. Pulling the clutch lever towards the grip causes the pressure plate to retract, allowing the friction and steel plates to spin freely. This disconnects the engine from the transmission, halting power to the rear wheel, and allowing gears to be changed.

Throttle: Your Ride's Accelerator

The throttle, or the right handlebar grip, is your motorcycle's accelerator. Twisting the throttle controls fuel and air flowing into the engine, adjusting power output. Accelerating is achieved by twisting the throttle towards you, while rolling it away slows you down.

Motorcycle racer turning around a bend

Brakes: Stopping Power at Your Fingertips and Toes

Motorcycles feature two independent brakes – one for the front wheel, controlled by a lever on the right side of the handlebar, and one for the rear wheel, operated by a foot pedal. The front brake is operated by pulling a lever that actuates the brake through either a cable pull or hydraulic fluid compression. The rear brake pedal allows riders to maintain full throttle control, useful for slow starts and stops.

Brakes work by transferring force from levers through an incompressible fluid to caliper pistons, pressing brake pads against discs. To transfer this force effectively, brake lines must not expand, leak, or compress the fluid. The types of brakes used include disc brakes, common on larger motorcycles due to their higher braking power, and drum brakes, found on smaller motorcycles or as rear brakes where less braking power is needed.

Exhaust: Where It All Ends

Motorcycle exhaust systems route hot, noxious exhaust gases from the engine away from the rider and into the open air. They also play a key role in optimizing engine performance by properly managing exhaust flow and backpressure.

Some motorcyclists choose to upgrade their exhaust systems for better performance, fuel efficiency, or sound enhancement. However, modifications must conform to local laws and regulations, particularly those concerning noise and emissions.

Suspension: Your Bike’s Shock Absorbers

The suspension system on a motorcycle includes components that connect the wheels to the frame. The main tasks of the suspension are to ensure good road holding and to cushion the rider and luggage from bumps. The system typically consists of a combination of springs and dampers, which work together to cushion the effects of the road surface, providing a smoother ride.

Front suspension is often in the form of telescopic forks, while the rear suspension, or the swingarm, varies more widely. Most motorcycles use either dual-shock or monoshock absorbers at the rear.

Tires: Your Contact with the Ground

Motorcycle tires provide the only contact with the ground and are therefore critical for speed, safety, and performance. They have to handle more weight compared to car tires, as they are responsible for transferring all the forces from the engine, braking system, and steering.

Motorcycle tires fall into three main categories: cruiser, street, and off-road. They also vary in profile, construction (radial or bias-ply), and tread pattern depending on their intended use.

A closeup of a motorcycle tire and exhaust

Other Vital Components

Several other components work in unison to make your ride safe and enjoyable. These include the horn, which works by activating an electromagnet that stretches a diaphragm; pegs, which are essential for resting and protecting your feet while riding; engine guards that shield your engine in case of an accident; and signal lights, headlights, and mirrors, which ensure visibility and safety.

There are several other minor components and accessories on a motorcycle, including the seats, luggage compartments, and additional electronic systems such as ABS, traction control, and riding modes. However, the ones mentioned above are the major components that define how a motorcycle operates. Remember, understanding your motorcycle is the first step to becoming a better, safer rider. So get to know your bike, treat it well, and it will give you many miles of thrilling adventures!