Acceleration: The rate of change of velocity or speed. Velocity is steady and is measured in distance per time (e.g., feet per second, miles per hour, kilometers per hour). Acceleration keeps increasing and is measured in velocity per time (e.g., feet per second per second or feet per second squared)

After Market: Any bike part that isn't factory built. (Doesn't come on factory bike.)

Air box: The plastic box that contains the air filter, protecting it from the elements. Located underneath the seat.

Air filter: Foam piece that removes dirt and water from the air before it reaches the carburetor.

Amateur: Any rider not on the professional level. i.e. beginner, novice, intermediate, expert

Arm pump: Forearm fatigue caused from the strain of riding for an extended period of time.

Attack Position: The body position a rider has when he is accelerating or air bourne.

Axle: Shaft that holds the wheel on the bike. Attached to the front suspension on the front of the bike and the swing arm on the rear.

Backflip: A freestyle trick in which the rider loops out 360 degrees and lands it.

Backward Falling Gate: Starting gate that falls towards the riders.

Bail: A bundle of hay. Also, a rider that purposely ditches the bike to avoid injury.

Banging Bars: Is when you and an opponent are having an intense battle for position and there may be contact involved.

Bar Hop: A freestyle trick in which the rider puts both feet over the handlebars between his arms and then replaces them for the landing.

Bark busters:For riding in dense tree areas, metal pieces on handlebars that protect hands from trees.

Bar Mount: Metal clamp that connects the handlebars to the triple clamp.

Bar Pad: The protection device made of foam found on the crossbar of the handlebars.

Bars: Handlebars.

Base Gasket: The gasket directly below the cylinder and between the cylinder and crankcase.

Basket case: An old bike which probably does not run. Often many engine and transmission parts have been removed and are either missing or stored in the trunk or a "basket".

Bean oil: Premix oil made from beans. Blendzall.

Beginner: The lowest amateur skill level of racing. Beginner, Novice, Intermediate, Expert

Berm: A berm is the built up outside edge of a corner on the track.

Big bike open: A racing class. Any skill level rider that rides a bike 125cc and above can enter.

Big bikes: Any dirtbike that is 125cc or larger.

Big Wheel: Any motocross bike that is bigger than an 80, but smaller than a 125. This term usually refers to the Kawasaki 85cc big wheel and the newer 100cc bigwheel.

The Bike Died: Any time the bike's engine stops running unintentionally.

Bike stand: A metal device used to hold up a dirtbike when it is stationary. Also called a stand.

Black Flag: The disqualification flag. If you see this flag, you are automatically scored in last place.

Bleed the brakes: Removing air from brake lines by irrigating brake fluid.

Blip the Throttle: When a rider gives the bike a quick, short burst of throttle. Can be used to control bike in drastic situations.

Block pass: Racing term. Used when one rider passes by aggressively cutting in front of another. In some cases, physical contact is made.

Blown Fork Seal: Fork seal that is visibly leaking fork oil.

Blue flag, Yellow stripe: Shown to a rider who must move over as he is being lapped by a faster rider.

Blue Groove: When the dirt on the track is very dry and hardpacked and it appears blue or black from the rubber worn off of tires.

Bobble: When a rider falls or makes a mistake while riding.

Bogging: Term referring to the low pitch sound of a  bike engine that is not getting full power.

Bogging down: When you are trying to accelerate and your bike is not in the power band.

Bottom Dead Center: (BDC) The lowest point of the piston and connecting rod travel in a cylinder.

Bottomed Out: When a bike's shocks are completely compressed due to a hard landing.

Brain Fade: Occurs when a rider has not trained properly, causing him to lose mental stamina while racing. Riders with brain fade lose energy and feel worn out, not wanting to ride 100% for the entire race.

Brake check: Racing term. Front rider quickly applies brakes, causing back rider to slow down or possibly rear end the front rider.

Brake pads:  The friction material or lining which is secured to metal plates. They press against the brake disc or rotor to enable the wheel to stop.

Brake Pin: Metal piece on the brake caliper that holds the brake pads in place.

Brake Slide: When you enter a corner and the back tire slides out due to locking up the back brake.

Braking Bumps: Places on track just before corners where riders have continually used brakes, creating small bumps.

Cable Luber: Device used to lubricate the clutch cable.

Caliper: 1. The apparatus on disc brakes which hold the disc pads and straddles the disc. When actuated the pads press against the disc to stop or slow the vehicle. 2. An adjustable measuring tool that is placed around (outside caliper) or within (inside caliper) an object and adjusted until it just contacts. It is then withdrawn and the distance measured between the contacting points.

Can-can: A freestyle trick in which a rider puts one foot over the seat in front of the other and replaces it for the landing.

Candy Bar: A freestyle trick in which a rider puts one foot over the bars and replaces it for the landing.

Came in Hot: Racing term. When rider carries a high amount of momentum into a corner.

Came Up Short: When a rider fails to completely clear an obstacle.

Camelback: A jump built into the track. One bigger ramp in the center of two smaller ramps.

Carburetor:  A device that vaporizes fuel and mixes it with air in proper quantities and proportions to suit the varying needs of the engine. A filter screens the air which is drawn into the carburetor. Here the gasoline mixes with the air and this fuel vapor enters the combustion chamber through the intake valve where it is compressed and burned.

The Card: A rectangular board, usually a pit board, used by the starter to countdown to the start of the race. When the starter turns the board sideways, the riders know that the gate will drop within five seconds.

Case: 1. The bike transmission. 2. When the rider misjudges the distance of a jump and the bottom of the bike hits the ground.

Case Cover: A metal piece on the side of the transmission that covers the clutch components.

Case plate: Metal plate underneath bike which protects the transmission.

Catapult: A steep jump that allows rider to gain a lot of height.

CC: Stands for cubic centimeters. A metric form of measurement used to measure the volume of the amount of oil in the gear box and the amount of space in the cylinder. This determines the size of the motorcycle. ie: 125cc

Chain: A piece of linked metal that runs from the front sprocket to the back sprocket. Makes the rear wheel turn.

Chain Adjuster: Bolt found on the rear of the swingarm which is loosened or tightened to change the slack on the chain. When adjusted, the rear wheel moves forward and backward.

Chain Lube: Liquid used to protect the chain from dirt, rust, and wear.

Chain Roller: Keeps the chain from hitting the frame and the swing arm.

Chain Slider: A rubber piece that protects the swingarm from the chain.

Charging a Corner: When a rider approaches a corner very quickly and aggressively.

Chassis: Generally, chassis refers to the frame, engine, front and rear axles, springs, steering system, and fuel tank. In short, everything but the body or cab and fenders.

Checkered flag: Waved by track official to signal the end of the race.

Choke: A butterfly valve or plate located near the top of the carburetor that limits or restricts the amount of air allowed to enter the carburetor, thus enriching the fuel-air mixture and enabling the bike to start and run more easily when cold.

Chop the throttle: Suddenly letting off of the throttle while accelerating.

Circlip: Small circular metal piece that holds the wrist pin in place inside the piston.

Class: Division of skill levels between riders.

Clicker: A stylish trick a rider does while airborne. He lays the motorcycle flat while bringing the back of the bike around.

Clutch: A device that disconnects the engine from the transmission, to allow the vehicle to change gears, and then allows the engine and transmission to resume contact and turn together at a new speed. The clutch consists of a series of parts: clutch lever, clutch cable, clutch perch, clutch adjuster, pressure plate, springs, basket, fiber and metal plates.

Clutch Adjuster: A system that tightens or loosens the the clutch lever. It is located on the clutch cable and on the clutch perch.

Clutch Basket: Metal piece in the transmission that holds the clutch plates.

Clutch Cable: Line running between the clutch lever and the transmission. Allows the clutch to engage and disengage.

Clutch Cover Gasket: Rubber piece that forms a seal between the clutch cover and the transmission, keeping oil in and maintaining pressure.

Clutch Lever: A metal piece attached to the left side of the handlebars. Engages and disengages the clutch.

Clutch Perch: The metal piece that holds the clutch lever onto the handlebar and connects the clutch cable to the clutch lever.

Clutch plate: Discs that remove the force of the motor from the transmission. Made of metal or fiber.

Clutch Spring: Metal device used to keep pressure between the clutch basket, clutch plates, and the pressure plates. Located in the transmission.

Coffin: A freestyle trick where a rider lays back on the bike and sticks his feet forward while holding on to the handlebars.

Coil:A pulse-type transformer for increasing the voltage to fire the spark plugs.

Compress: Technical style of ramp jumping in which the rider utilizes the suspension to jump higher. (detailed description in school)

Compression: One of the essential factors in internal combustion engine (fuel, air, proper proportion of mixture, compression, timing, spark). It is the squeezing of the fuel-air mixture in the cylinder of a spark-ignition engine. Compression makes the process of combustion more effective and increases engine efficiency.

Compression Stroke: The second stroke of the four-stroke cycle, in which the piston moves upward from bottom dead center to top dead center, compressing the fuel-air mixture.

Concrete Start: Starting pad that is made of concrete.

Conditions: The state that the track is in--muddy, tacky, or hardpacked.

Conventional Forks: A form of suspension more commonly used in the past, female component holds the axle, male component is held by the triple clamp.

Coolant: Liquid in the cooling system. Usually a mixture of water and antifreeze (ethylene glycol). This mixture lowers the freezing point of the water in the cooling system, prevents rust and corrosion, lubricates the water pump, and picks up heat from the engine and transfers it to the air passing through the radiator.

Cordova: A freestyle trick in which the rider puts his feet up to the bars and does a backbend, then replaces his feet back onto the pegs for the landing.

Crossbar: A part of the handlebar that gives it added support.

Cubic centimeter: See CC.

Cylinder: Metal piece that sits on top of transmission, allows the piston and rings to operate along with the spark plug to make the engine fire.

Cylinder bored: Widening the cylinder to give more space for a larger piston and ring.

Cylinder Head: The detachable metal (aluminum or iron) section that is bolted to the top of the cylinder block. It is used to cover the tops of the cylinders, in many cases the cylinder head contains the valves, it also forms part of the combustion chamber. It has water and oil passages for cooling and lubrication.

Cylinder Sleeve: Innermost part of the cylinder which comes in contact with the piston ring.

Dash for Cash: A race held during intermission at some events where riders pay to enter and the first place finisher wins all of the entry fees.

Dead Sailor: When a rider jumps over a freestyle jump and does not attempt a trick.

Decompress: Technical style of ramp jumping where the rider tries to stay as low as possible over the jump so that he can get back on the ground as soon as  possible.

Disc brake: A type of brake that has two basic components: a flat rotor (disc) that turns with the wheel and a caliper that is stationary. When the brake pedal is depressed, linkage (mechanical or hydraulic) causes the caliper to force its heat-resistant brake pads against both sides of the rotating disc thus slowing or stopping the wheel.

Ditch the Bike: When a rider for any reason jumps off his bike.

DNF: Scorekeeping term, stands for "did not finish".

DNS: Scorekeeping term, stands for "did not start". As in the rider did not start the race.

Docked a Lap: When for any reason a rider is penalized by losing a lap on the field. Could be caused by double jumping on a yellow flag.

Double jump: Jump made of two ramps. Rider should clear both ramps and land on the downside of the second.

Down hill: The downward sloping area of a track.

Drop the clutch: When a rider quickly lets out the clutch.

Dust Bowl: When the track is very dusty and causes limited vision for riders.

Dyno: A machine used to measure the horsepower and torque of an engine.

Endo: When rider pitches forward at an angle on bike. Could lead to a face plant.

Exhaust Port: Part of the cylinder where the exhaust fumes leave the cylinder and enter the exhaust pipe.

Expansion Chamber: The widest part of an exhaust pipe.

Expert: The highest skill level of amateur racing. Beginner, Novice, Intermediate, Expert

Face Mask: Plastic piece connected to the helmet that protects the face from dirt and debris. Old school.

Face plant: When rider crashes and lands on his face.

Fade: When a rider gets worn out and drops back in the field.

Fender grab: A freestyle trick in which the rider grabs one of the fenders.

Filter Oil: Product put on the air filter to help keep dust and debris from entering the engine.

Finesse: When the rider lets the bike work for him to be as smooth as possible in his technique.

First turn: The first corner in the track following the drop of the gate. Also the point where the holeshot is determined.

Flag Mount: Metal piece that holds a flag onto the bike's swingarm when riding in the dunes.

Flagger: Track workers that are placed on the side of the track and look for hazards on course such as crashes or animals. When a hazard is spotted they wave a yellow flag.

Float: 1. A small hollow tank which is more buoyant than the liquid in which it is immersed. In a carburetor it operates the valve (needle and seat) which controls the amount of fuel entering the carburetor. In the fuel tank, it indicates the amount of fuel. Also see valve float. Older floats were hollow and made of metal, but newer ones were made of a solid synthetic material. 2. The action of the breaker arm when it is pushed out as the cam strikes the rubbing block; and before the arm can return after the cam has passed, the next cam strikes the block and re-opens it. In other words, the breaker arm never has the time to fully close before being opened again.

Float Bowl:That part of a carburetor that acts as a reservoir for gasoline and in which the float is placed. The float controls the amount of fuel moving through the fuel valve.

Flooded: When too much fuel enters the cylinder and drowns out the spark plug, causing the bike not to start.

Fly wheel: A relatively large and heavy wheel that is attached to the back of the crankshaft to smooth out the firing impulses. It provides inertia to keep the crankshaft turning smoothly during the periods when no power is being applied. It also forms a base for the starter ring gear and, in manual transmission, for the clutch assembly. Also called "engine flywheel."

Foot peg: Metal piece connected to the frame that the rider stands on.

Fork guards: Plastic cover for the male section of the front suspension, protects it from dirt and debris.

Fork Oil: Product used for pressure and lubrication in the front suspension of a motorcycle.

Fork Seal: Rubber piece on front suspension which keeps fork oil from leaking out and creates an air tight seal within the suspension system.

Fork Spring: A spring found in each tube of the front suspension. Used to absorb impact and rebound the suspension.

Fork Tube: Hollow metal part of the front suspension which holds the spring and allows the male section to operate.

Forward Falling Gate: Starting gate that falls away from the riders.

Four stroke: An engine requiring two complete revolutions of the crankshaft to fire each piston once. The first stroke down (intake stroke) pulls fuel and air into the combustion chamber. The second stroke up (compression stroke) compresses the mixture. The third stroke down (power stroke) comes about through the rapid burning of the compressed fuel mixture. The fourth stroke up (exhaust stroke) expels the exhaust gases from the cylinder. It is also called the "Otto cycle."

Frame Guard:A metal or plastic piece that attaches to the frame above the foot pegs. It protects the frame from wear and tear.

Free Sag: A term used when setting race sag. Also none as Static Sag. This is the measurement of how much the suspension droops without the rider and is one way of measuring whether the spring is too light or too stiff for the rider.

Freestyle: Style of riding in which riders perform tricks over jumps.

Freestyle Ramps: A jump that is specifically designed to perform tricks.

Freestyle Track: A track with jumps that are specifically designed to perform freestyle tricks on.

Front Brake Cable:Line running between the front brake reservoir and the front brake master cylinder. Transfers pressure produced by the brake lever through the line to the master cylinder.

Front Brake Master Cylinder: The part of the hydraulic brake system which stores the brake fluid. As the brake pedal is applied pressure is forced against a small movable piston in the master cylinder to push hydraulic fluid through the lines to the wheel cylinders and force the brake linings against the drum (in the case of drum brakes) or force the brake pads against the disc (in the case of disc brakes).

Front Brake Reservoir: Small container found on the subframe which holds the excess brake fluid.

Front end washes out: When the front end of the bike slides sideways due to loss of traction while in motion. Can cause a crash.

Front Number Plate: Plastic piece on the front of the bike used to block debris and display racing number.

Front Suspension: Two metal pieces that connect from the triple clamp to the axle, that absorb the impact of the track terrain.

Full waffle grips: Grips which are fully textured.

Gas Cap: The lid on the gas tank which is removed to check level of fuel or in order to add fuel.

Gas Tank: The container for holding or storing fuel, located between the seat and the radiator shroud.

Gasket: A material made of asbestos, cardboard, cork, paper, rubber, or soft metal placed between two metal parts to insure proper sealing.

Gear: Wheel-like part with teeth cut into the rim. When one gear meshes with another gear, it causes the second gear to drive the other and in this way transmits power. When the gears are different sizes (different number of teeth on each gear) the mechanical average is changed. Can also refer to riding apparel.

Gear Bag: Bag used to carry any gear or items used when riding.

Gear box: The device in the drivetrain consisting of an input shaft, a system of gears, and an output shaft that multiplies engine torque. A manual transmission consists of a clutch assembly plus a gearbox; and automatic transmission generally consists of a torque converter plus gearbox.

Gear Ratio: The relationship between the number of turns made by a driving gear to complete one full turn of the driven gear. If the driving gear turns four times to turn the driven gear once, the gear ratio would be 4 to 1. In most instances, the gear ratio is not even like 4:1 because the same teeth would be meshing with each other. Thus a ratio of 4.11:1, for instance, means that a particular tooth on one gear may eventually mesh with every one of the teeth on the other gear. Changing the tire size will change the effective gear ratio.

The Gate: Refers to the starting gate or the gate which encloses the entire track grounds.

The Gate Opens: The designated time that the track grounds are open to the public.

Goggle Lens: (Lens) Transparent plastic part of goggles that shield eyes from debris. Come in several types: orange, gradient, clear, yellow, mirror, gray, smoke, hologram, fog resistant, double pane.

Goggles: Eye protection used by motocross racers.

Going Big: When a rider jumps especially high on a ramp.

Goon: An outdated, inappropriate, dangerous, or squarely rider. AKA: Spode, Nerd, Dork, Squirrel

Grab holes:Holes found under the seat which freestyle riders use to hold on to the bike when doing certain tricks.

Graphics: Stickers on the plastic of the bike used for looks and advertisement.

Green flag: Held by a track worker on the finish line to indicate to riders that the first lap of the race has been completed.

Grips: Rubber pieces which cover the ends of the handlebars. Provide traction and impact absorption.

Half Waffle Grips: Grips which are half smooth and half textured.

Hand guards: Plastic covers connected to the front of handlebars which protect rider's hands from dirt and debris.

Handlebars: The part of the bike that you hold on to. Found under the grips.

Hardpack: Track condition in which the ground is dry and firm.

Head:A part of the engine which covers the piston and creates the combustion chamber. The proper name is cylinder head.

Head Gasket: The gasket at the top of the cylinder and sits between the cylinder and the head. It keeps the coolant out of the cylinders and retains compression in the cylinder.

Head milled: To remove metal from the bottom of the head of the engine through the use of a rotating toothed cutter. Decreases air space in the engine and increases compression.

High RPM: When the engine is running in mid to full throttle. RPM stands for rotations for minute. 1 rpm is when the crankshaft makes 1 full rotation.

High side:When a rider loses balance on a turn and tips towards the outside of the turn, causing him to crash.

Holeshot: The rider in the lead around the first turn at the start of the race.

Hub: The center of a wheel consisting of a shell to which spokes attach and contains an axle along with two sets of bearings.

Idle: The engine speed when the vehicle is not moving. The engine's slowest practical speed.

Idle Screw: On a motocross bike it is normally the choke. If you turn it you can adjust the idle of your bike.

Indian air: A freestyle trick in which the rider puts his legs behind the bike and crosses them, then replaces them for the landing.

Indoor: Any event held inside a stadium or covered arena, out of the elements.

Inside line: Part of the track that is on the inner curve of a turn.

Intake Boot: Plastic piece that channels the air from the air box to the carburetor.

Intake valve: The valve that opens to permit the fuel mixture into the cylinder. It closes during the compression and combustion strokes. Some engines have more than one intake valve to each cylinder. Also called the "inlet valve."

Intermediate: The amateur skill level of racing just below expert. Beginner, Novice, Intermediate, Expert

Inverted Forks: Commonly called "upside down forks". Male component holds the axle and female component is held by the triple clamp.

Intake Port: Opening in the cylinder where fuel enters.

Jet: A fuel tube or pipe in the carburetor, into which air is admitted through one or more holes to compensate for a tendency of the main nozzle to deliver too rich a mixture as the air velocity through the carburetor increases. Also called "air bleed."

Jetting: When you adjust the size of components in your carburetor to get the proper mixture of gas and air.

Johnny: A portable track restroom.

Jump-off Contest: Any type of jumping competition.

Jump the Gate: When a rider takes off before the starting gate drops and possibly becomes caught.

Kick it Over: When you attempt to kick start a bike.

Kick Starter: Metal lever on the right hand side of the bike that is used to start the engine.

Kicker: A short jump that has a sharp angle to the ground on the launch. Kicker jumps are notorious for bucking riders over the bars.

Kidney Belt: A protective wrap worn around the waist the guards the kidneys from injury.

Kill Switch: A button located on the left side of the handlebars. When pushed turns off bike.

Kill the bike: Any situation where the engine mistakenly stops.

Knee Brace: Device used to give the knee support when riding. Made of metal, hard plastic, and fabric.

Knee Pads: Protective pads used to guard the knee from injury when riding.

Knobby: A tire.

Knobs:

Lap: One full run around a track that ends at the finish line.

Lapper: A rider that gets a full lap behind in a race.

Last Chance Qualifier:(LCQ) In the main event style racing format this is the last opportunity for the racer to advance to the main event.

Lever: A simple machine comprising an arm and a pivot. Can be found on the handlebars (clutch lever, brake lever).

Lifter: A lifter that uses hydraulic oil pressure to maintain no clearance between metal parts so that valve noise is reduced. Also it reduces wear on the valves and eliminates periodic valve adjustments.

Line: This describes the path of the motorcycle as a rider goes through a section of track or around a turn. Riders think hard about the best lines to take, lines that can be used for passing, and lines to be used later in a race when the track surface has changed.

Linkage: A series of rods, yokes, levers, bars or links used to transmit motion from one unit to another. Connected from the swingarm to the rear shock.

Look back: When a rider glances behind him to assess where the other racers are in relation to him. Also can be a freestyle trick done by a goon.

Loopout: When a rider is in the air and the front end goes too high. Can cause panic rev or a crash. Can be corrected by tapping the back brake.

Low End: Lower section of the powerband. Also can refer to the lower part of the engine. Connecting rod and crankshaft.

Low RPM: When the engine is running at mid to low throttle. RPM stands for rotations per minute. 1 rpm is when the crankshaft does one full rotation.

Magneto: An electrical device which generates electrical current when it is rotated by an outside source of power. It needs no outside source of power such as a battery. It may produce either low or high tension current.

The Main: (Main Event)

Main Jet: Metal piece located inside the carburetor used to mix air and fuel.

Marbley: Track condition. When the track consists of small clots of dirt that are dry and hard.

Master cylinder: The primary component for pressurizing fluid in a hydraulic system. Used in the braking system, it supports a reservoir for holding brake fluid and is activated each time the driver depresses the brake pedal.

Master link: A special link on a chain that can be opened by flexing a plate, removing a screw, or some other means besides driving out a rivet. The retaining spring clip is shaped like a fish with a round head and twin tails.

Match the cases: Engine modification where both parts of the transmission are aligned perfectly to increase engine performance.

Midrange: Middle section of the powerband.

Mini: Another name for an 80cc dirt bike or an 80cc racing class.

Modified: Any bike that has after market parts on it or has had work done on the engine or suspension. This is also a racing class where only modified bikes may enter.

Mud Flap: A plastic cover connected to the airbox. Protects the shock from debris.

Mulisha Air: (Superman seat-grab) A freestyle trick.

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