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)
Market: Any bike part that isn't factory built. (Doesn't come on
plastic box that contains the air filter, protecting it from the
elements. Located underneath the seat.
piece that removes dirt and water from the air before it reaches the carburetor.
rider not on the professional level. i.e. beginner, novice,
fatigue caused from the strain of riding for an extended period of time.
Position: The body position a rider has when he is accelerating
or air bourne.
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.
A freestyle trick in which the rider loops out 360 degrees and lands it.
Falling Gate: Starting
gate that falls towards the riders.
A bundle of hay. Also, a rider that purposely ditches the bike to
Bars: Is when you and an opponent are having an intense battle
for position and there may be contact involved.
freestyle trick in which the rider puts both feet over the
handlebars between his arms and then replaces them for the landing.
riding in dense tree areas, metal pieces on handlebars that protect
hands from trees.
Mount: Metal clamp that connects the handlebars to the triple clamp.
protection device made of foam found on the crossbar of the handlebars.
Gasket: The gasket directly below the cylinder and between the
cylinder and crankcase.
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".
oil made from beans. Blendzall.
The lowest amateur skill level of racing. Beginner, Novice,
berm is the built up outside edge of a corner on the track.
open: A racing class. Any skill level rider that rides a bike 125cc
and above can enter.
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.
Bike Died: Any time the bike's engine stops running unintentionally.
stand: A metal device used to hold up a dirtbike when it is
stationary. Also called a stand.
Flag: The disqualification flag. If you see this flag, you are
automatically scored in last place.
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.
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.
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.
When a rider falls or makes a mistake while riding.
referring to the low pitch sound of a bike engine that is not
getting full power.
down: When you are trying to accelerate and your bike is not in the
Dead Center: (BDC) The lowest point of the
piston and connecting rod travel in a cylinder.
Out: When a bike's shocks are completely compressed due to a hard landing.
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.
friction material or lining which is secured to metal plates. They
press against the brake disc or rotor to enable the wheel to stop.
Pin: Metal piece on the brake caliper that holds the brake pads
When you enter a corner and the back tire slides out due to locking
up the back brake.
Bumps: Places on track just before corners where riders have
continually used brakes, creating small bumps.
Luber: Device used to lubricate the clutch cable.
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.
A freestyle trick in which a rider puts one foot over the seat
in front of the other and replaces it for the landing.
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.
Short: When a rider fails to completely clear an obstacle.
jump built into the track. One bigger ramp in the center of two
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.
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
The bike transmission. 2. When the rider misjudges the distance of a
jump and the bottom of the bike hits the ground.
Cover: A metal piece on the side of the
transmission that covers the clutch components.
plate underneath bike which protects the transmission.
steep jump that allows rider to gain a lot of height.
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.
piece of linked metal that runs from the front sprocket to the back
sprocket. Makes the rear wheel turn.
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.
Lube: Liquid used to protect the chain from dirt, rust, and wear.
the chain from hitting the frame and the swing arm.
Slider: A rubber piece that protects the
swingarm from the chain.
Charging a Corner: When a rider
approaches a corner very quickly and aggressively.
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.
flag: Waved by track official to signal
the end of the race.
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.
throttle: Suddenly letting off of the throttle while accelerating.
Small circular metal piece that holds the wrist pin in place inside
Division of skill levels between riders.
A stylish trick a rider does while airborne. He lays the motorcycle
flat while bringing the back of the bike around.
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.
Adjuster: A system that tightens or
loosens the the clutch lever. It is located on the clutch cable and
on the clutch perch.
Basket: Metal piece in the transmission that holds the clutch plates.
running between the clutch lever and the transmission. Allows the
clutch to engage and disengage.
Cover Gasket: Rubber piece that forms a seal
between the clutch cover and the transmission, keeping oil in and
Lever: A metal piece attached to the left
side of the handlebars. Engages and disengages the clutch.
metal piece that holds the clutch lever onto the handlebar and
connects the clutch cable to the clutch lever.
that remove the force of the motor from the transmission. Made of
metal or fiber.
Spring: Metal device used to keep pressure between the clutch
basket, clutch plates, and the pressure plates. Located in the transmission.
A freestyle trick where a rider lays back on the bike and sticks
his feet forward while holding on to the handlebars.
pulse-type transformer for increasing the voltage to fire the spark plugs.
Technical style of ramp jumping in which the rider utilizes the
suspension to jump higher. (detailed
description in school)
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.
second stroke of the four-stroke cycle, in which the piston moves
upward from bottom dead center to top dead center, compressing the
Start: Starting pad that is made of concrete.
The state that the track is in--muddy, tacky, or hardpacked.
A form of suspension more commonly used in the past, female component
holds the axle, male component is held by the triple clamp.
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.
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.
A part of the handlebar that gives it added support.
centimeter: See CC.
piece that sits on top of transmission, allows the piston and rings
to operate along with the spark plug to make the engine fire.
bored: Widening the cylinder to give more space for a larger piston
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.
Sleeve: Innermost part of the cylinder which
comes in contact with the piston ring.
for Cash: A race held during intermission at some events where
riders pay to enter and the first place finisher wins all of the
Sailor: When a rider jumps over a freestyle jump and does
not attempt a trick.
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.
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.
the Bike: When a rider for any reason
jumps off his bike.
Scorekeeping term, stands for "did not finish".
Scorekeeping term, stands for "did not start". As in the
rider did not start the race.
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.
jump: Jump made of two ramps. Rider should clear both ramps and
land on the downside of the second.
hill: The downward sloping area of a track.
the clutch: When a rider quickly lets out the clutch.
Bowl: When the track is very dusty and causes limited vision for riders.
A machine used to measure the horsepower and torque of an engine.
When rider pitches forward at an angle on bike. Could lead to a face plant.
Port: Part of the cylinder where the exhaust fumes leave the
cylinder and enter the exhaust pipe.
Chamber: The widest part of an exhaust pipe.
The highest skill level of amateur racing. Beginner, Novice,
Mask: Plastic piece connected to the helmet that protects the
face from dirt and debris. Old school.
plant: When rider crashes and lands on his face.
When a rider gets worn out and drops back in the field.
grab: A freestyle trick in which the rider
grabs one of the fenders.
Oil: Product put on the air filter to help keep dust and debris
from entering the engine.
the rider lets the bike work for him to be as smooth as possible in
turn: The first corner in the track following the drop of the
gate. Also the point where the holeshot is determined.
Mount: Metal piece that holds a flag onto the bike's swingarm
when riding in the dunes.
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.
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.
When too much fuel enters the cylinder and drowns out the spark
plug, causing the bike not to start.
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
piece connected to the frame that the rider stands on.
cover for the male section of the front suspension, protects it from
dirt and debris.
Product used for pressure and lubrication in the front suspension of
Seal: Rubber piece on front suspension which keeps fork oil from
leaking out and creates an air tight seal within the suspension system.
Spring: A spring found in each tube of the
front suspension. Used to absorb impact and rebound the suspension.
Tube: Hollow metal part of the front suspension which holds the
spring and allows the male section to operate.
Falling Gate: Starting gate that falls away from the riders.
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
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.
Style of riding in which riders perform tricks over jumps.
Ramps: A jump that is specifically
designed to perform tricks.
Track: A track with jumps that are
specifically designed to perform freestyle tricks on.
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).
Brake Reservoir: Small
container found on the subframe which holds the excess brake fluid.
end washes out: When
the front end of the bike slides sideways due to loss of traction
while in motion. Can cause a crash.
Number Plate: Plastic piece on the front of the bike used to
block debris and display racing number.
metal pieces that connect from the triple clamp to the axle, that
absorb the impact of the track terrain.
waffle grips: Grips
which are fully textured.
lid on the gas tank which is removed to check level of fuel or in
order to add fuel.
container for holding or storing fuel, located between the seat and
the radiator shroud.
material made of asbestos, cardboard, cork, paper, rubber, or soft
metal placed between two metal parts to insure proper sealing.
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.
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.
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.
to the starting gate or the gate which encloses the entire track grounds.
Opens: The designated time that the track grounds are open to the public.
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.
Eye protection used by motocross racers.
Big: When a rider jumps especially high on a ramp.
An outdated, inappropriate, dangerous, or squarely rider. AKA:
Spode, Nerd, Dork, Squirrel
holes:Holes found under the seat which freestyle riders use to
hold on to the bike when doing certain tricks.
on the plastic of the bike used for looks and advertisement.
by a track worker on the finish line to indicate to riders that the
first lap of the race has been completed.
pieces which cover the ends of the handlebars. Provide traction and
Waffle Grips: Grips
which are half smooth and half textured.
covers connected to the front of handlebars which protect rider's
hands from dirt and debris.
The part of the bike that you hold on to. Found under the grips.
Track condition in which the ground is dry and firm.
part of the engine which covers the piston and creates the
combustion chamber. The proper name is cylinder 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.
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.
side:When a rider loses balance on a turn and tips towards the
outside of the turn, causing him to crash.
rider in the lead around the first turn at the start of the race.
center of a wheel consisting of a shell to which spokes attach and contains
an axle along with two sets of bearings.
engine speed when the vehicle is not moving. The engine's slowest
Screw: On a motocross bike it is normally the choke. If you turn
it you can adjust the idle of your bike.
freestyle trick in which the rider puts his legs behind the bike and
crosses them, then replaces them for the landing.
event held inside a stadium or covered arena, out of the elements.
of the track that is on the inner curve of a turn.
Boot: Plastic piece that channels the air
from the air box to the carburetor.
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
The amateur skill level of racing just below expert. Beginner,
Novice, Intermediate, Expert
Forks: Commonly called "upside down
forks". Male component holds the axle and female component is
held by the triple clamp.
Port: Opening in the cylinder where fuel enters.
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."
When you adjust the size of components in your carburetor to get the
proper mixture of gas and air.
portable track restroom.
Contest: Any type of jumping competition.
the Gate: When a rider takes off before the starting gate drops
and possibly becomes caught.
it Over: When you attempt to kick start a bike.
Starter: Metal lever on the right hand side of the bike that is
used to start the engine.
short jump that has a sharp angle to the ground on the launch.
Kicker jumps are notorious for bucking riders over the bars.
Belt: A protective wrap worn around the waist the guards the
kidneys from injury.
Switch: A button located on the left side
of the handlebars. When pushed turns off bike.
the bike: Any situation where the engine mistakenly stops.
Brace: Device used to give the knee support when riding. Made of
metal, hard plastic, and fabric.
Pads: Protective pads used to guard the knee from injury when riding.
One full run around a track that ends at the finish line.
rider that gets a full lap behind in a race.
Chance Qualifier:(LCQ) In the main event style racing format
this is the last opportunity for the racer to advance to the main event.
simple machine comprising an arm and a pivot. Can be found on the
handlebars (clutch lever, brake lever).
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.
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.
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.
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.
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
Main: (Main Event)
Jet: Metal piece located inside the carburetor used to mix air
Track condition. When the track consists of small clots of dirt that
are dry and hard.
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.
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
Match the cases: Engine
modification where both parts of the transmission are aligned
perfectly to increase engine performance.
section of the powerband.
Another name for an 80cc dirt bike or an 80cc racing class.
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.
Flap: A plastic cover connected to the
airbox. Protects the shock from debris.
Air: (Superman seat-grab) A freestyle trick.