2-valve
- a motorcycle engine with two total valves in each cylinder, 1
intake valve, 1 exhaust valve.
4-valve - a motorcycle engine with four total valves
in each cylinder, 2 intake valves, 2 exhaust valves. Generally an
engine with a higher number of valves in each cylinder will generate
more power, because it can flow more fuel/air and exhaust per cycle
due to greater valve area.
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ABS
Brakes - (Anti-lock Braking System) an innovation pioneered
in cars that is now (2003) slowly making its way into the motorcycle
world starting with touring and sport touring bikes. A system that
quickly activates and releases the calipers on disc brakes during
intense braking. This helps the brake avoid lockup, and reduces
the chances of a skid.
ABS Plastic - (Acrylonitrile-Butyl-Styrene Plastic)
impact- and abrasion-resistant hard plastic. Can be molded and melted
quite readily. Used for helmets, armor, fairings and other parts
of bikes.
Adventure-Touring - a motorcycle that is meant
for touring and light off-road duty. Examples include: Triumph Tiger,
Suzuki V-Strom.
Aftermarket - a part not supplied by the original
equipment manufacturer. Not stock. These parts can add functionality,
improve upon stock, or change appearances, among other things.
Air Box - A plastic or fiberglass "tub" which contains
the air filters on a motorcycle. On many bikes the sole purpose
of the airbox to provide a place to mount these filters. On many
sportbikes, the air box is used as part of a ram-air system or other
performance enhancing intake system.
Air Shifter - A device used in drag racing which
activates the gear shifter pneumatically. Air shifters enable faster
and more consistent shifts.
Air Tubes - There are two types of air tubes on
a motorcycle. One kind of air tube is a duct that travels from the
air box on a motorcycle to the front of the bike, usually as part
of a ram-air system. It's purpose is to conduct air into the air
filter and thereby into the engine. The other type of air tube is
a small vent hose connected to the fuel bowls in a carburetor, designed
to equalize air pressure inside the carb.
Air Vest - new class of protective riding wear.
A vest and collar that inflate super-rapidly (around 30 milliseconds)
when they sense that the rider has been thrown from the bike. Sort
of the motorcycling equivalent of the airbag. Because of the collar,
they protect the neck from some injuries.
AMA - The American Motorcyclist Association. An
advocacy group and sports sanctioning body. Can be found online
at: http://www.ama-cycle.org
Ape Hangers - slang for very tall handlebars, usually
found on cruisers. If tall enough, they make the rider look like
an ape, hanging from a bar.
Armco Barrier - A roadside crash barrier consisting
of an extruded, lengthwise corrugated metal strip, attached at 3-5
foot intervals to vertical wooden posts (that look like telephone
pole stumps, 2-3 feet tall) set into the ground. Often known for
cutting off body parts if hit wrong. Also just called an Armco.
Armor - Plastic or composite plates that are added to leathers
and other specialized riding wear in order to provide extra protection
in a crash. Armor is usually located in key locations that are most
likely to need it, such as the elbows, knees, shoulders, and spinal
area.
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Bash Plate - A metal plate that is securely fastened
to the frame on dirt bikes, designed to protect the engine from
damage in the event of a crash or hitting an obstacle.
Before Top Dead Center - Crankshaft position at
the minimum compression of the fuel-air mixture, and the maximum
size of the cylinder cavity. The position of the crankshaft at the
end of the intake stroke and before the compression stroke. Measured
at the number one cylinder.
Belt Drive - A type of motorycle in which the engine
is connected to the rear wheel by means of a belt instead of a chain.
Belt drive systems are comparable to chain systems. A belt drive
takes up more space than a chain, but requires less frequent adjustment.
They are generally used on cruisers.
Big Bore - Describes an engine with a larger than
standard bore (cylinder diameter). See Bore for more information.
Billet - A "billet" is a solid lump of metal. It
usually refers to motorcycle parts that are machined from a large
bar of metal rather than being forged or cast. Billet parts are
usually of very high quality becasue they do not suffer from casting
imperfections.
Binder - slang for a brake
Biposto - Italian for two seat. If an Italian bike
is labeled biposto, it is the two-seat version of a model. Also
means traveling with a rider. One could say that "we were going
biposto on that particular rally. " The word biposto is used in
the same way as both "pillion" and "two-up".
Bleeding - The process of removing all trapped
air from a hydraulic line, such as a brake line or clutch line.
Body Bag - Slang for leathers or other protective
clothing.
Bore - The diameter of the pistons in a bike's
engine. Bore * stroke * number of cylinders = engine displacement
Boxer - A horizontally-opposed flat engine.
Braided Steel Lines - A type of pressure resistant
fluid transport or hydraulic pressure tubing. Made of thin steel
wiring braided together, surrounding a liner.
Brain Bucket - slang for helmet.
Bumpstick - Slang for camshaft. It refers to the
cam lobes.
Buns - Slang for tires.
Burnout - The process of spinning the rear tire
on a motorcycle by hitting the throttle hard while stopped. Some
people do this to show off.
In drag racing, drivers always perform a burnout prior to racing
becasue the heat generated by the burnout softens the tire, improving
traction during the race.
Butterfly Valve - A type of valve consisting of
a circle of material mounted mounted on a pivot. This circle normally
blocks the tube, but when rotated, opens an increasing amount of
the tube to passage of gas or fluids.
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Cager - Biker jargon for a person who drives a
car or truck.
Calipers - Part of the braking system on a motorcycle.
A caliper is a hydraulic clamp which is used to "grab" onto the
brake rotors (brake discs) in order to slow and eventually stop
the spinning of that wheel.
Cam Chain - A drive chain which connects the crankshaft
to the camshaft in most 4-stroke motorcycle engines.
Cam Chain Tensioner - A device which maintains
proper tension in a cam chain. Tension is required becasue a loose
chain could cause timing irregularities which would make the engine
run very rough, if at all. On many high-powered drag race bikes,
this part is upgraded to a heavy duty version.
Cam Lobe - The part of the camshaft extending away
from the shaft. They push on rockers, that in turn, open the exhaust
or intake valves on the cylinder.
Cans - Slang for exhaust pipes.
Carburetor - A mechanical device which controls
the amount of fuel and air entering an engine. Its primary purpose
is to meter the amount of gasoline and air such that there is the
correct ratio between the two.
Case Cover - A metal cover which covers one side
of an engine. On most bikes there are two, one on the left side
and one on the right side.
Usually, the left side cover conceals the starter, flywheel, and
ignition components while the right side cover conceals the clutch.
Cassette Gearbox - A gearbox that is easily removable,
enabling the owner, or a mechanic, to change transmission gears
easily, for reasons of breakage, customization, etc.
Cat's Eye - European term for a safety reflector.
These are sometimes mounted on motorcycles to increase visibility.
Centerstand - A device that is used to hold a bike
upright for parking purposes. A centerstand is a hinged stand located
under the bike's engine. It has two pads that contact the ground.
Unlike a kickstand, a center stand does not hold the bike in a leaning
position.
Chassis - Another word for the frame of a motorcycle.
The chassis is the structural backbone of the bike. The other parts--such
as wheels, suspension, engine, etc. are all mounted to the chassis.
Chain Guard - A part of a bike which surrounds
the drive chain. Its job is to prevent objects from contacting the
chain and to help contain the chain in the event of a chain breakage.
It can also help keep excess chain lubricant and road grime from
being thrown off the chain onto the bike.
Chain Lubrication - Routine maintenance that increases
the reliability and performance of the chain. Involves oiling or
waving the chain-link connections. Devices are available to perform
this task automatically. However, you still must check the chain
regularly, as in every time you stop for fuel.
Chain Snatch - A varying of the tension in the
drive chain that results in it whipping up. Can be caused by a lugging
engine.
Choke - A device attached to the air intake on
carbureted bikes.
It helps the engine start and warm up more quickly when cold by
making the fuel-air mixture richer.
Chopped - A motorcycle that has been converted
into a chopper.
Chopper - A motorcycle, usually a cruiser, that
has unique styling features including a very long, forward-angled,
front fork. Many choppers also have ape hangers, and a smaller than
normal front wheel.
Chugging - see Lugging.
Click - Slang for Kilometer. Also, refers to the
audiable "click" made by various adjustment knobs or screws on a
motorcycle. Someone might say "My rebound is set twelve clicks out".
This means that the rebound adjustment knob was turned all the way
in until it stopped, and was then unscrewed enough to click twelve
times.
Clip-ons - A special type of handlebar, usually
found on sport bikes.
Rather than one continous handlebar, clip-ons consist of a left
and right handgrip which mount directly to the front forks. They
are usually lower down and shorter than normal handlebars.
Close-ratio - A transmission in which the different
gear ratios are numerically similar to one another. In a close-ratio
transmission, there is not much difference between adjacent gears.
Clutch Basket - The outer portion of the clutch
in a motorcycle which contains the other clutch components.
Compression Damping - The damping provided by a
shock absorber or suspension fork as it compresses, such as hitting
a bump in the road.
Compression Ratio - The ratio between the cylinder
volume at its maximum (the end of the intake stroke) and its minimum
(the end of the compression stroke. ) Or, more technically, the
ratio between a given engine's cylinder volume at Before Dead Center
and its volume at Top Dead Center.
Contact Patch - The part of the tire in contact
with the road at any one time. The greater the area of the contact
patch, the greater the grip, or traction. This is why dragbikes
have very wide rear tires.
Cop House - Slang for a police station. Also, more
derogatorily, a donut or coffee shop.
Cornering Clearance - The degree to which a bike
can be leaned over to complete a turn. Determines cornering ability.
Sportbikes have thin, wedge-shaped lower frames, so have great cornering
clearance. Cruisers have wide, blocky lower frames, so have poor
cornering clearance. This doesn't mean that any bike is a poor cornering
machine, as most are at least on a par with racing automobiles.
Countersteering - When steering a motorcycle at
speed, the rider does not turn the handlebars in the direction of
the turn as he or she would when driving a car. Rather the handlebars
are turned slighly in the opposite direction of the intended turn,
and the rider leans the motorcycle into the turn.
Cow - Slang term for a very large cruiser, especially
one that is equipped with lots of accessories.
Crankcase - The lower portion of a motorcycle engine.
The crankcase contains the engine oil. Is sometimes used as a load
bearing frame member, and can be prestressed.
Crankshaft - Part of a motorcycle engine. The crankshaft
is a metal shaft with one or more offset sections (journals). The
connecting rods, and in turn, pistons, are connected to journals.
This allows the vertical motion of the pistons to be converted to
rotational motion. The crankshaft transfers power from the engine
to the outside world, usually through a transmission.
Crank Throw - The distance that the connecting
rod journals on a crankshaft are offset from the main bearing journals.
It is equal to one-half of the stroke of a given engine.
Crotch Rocket - Slang term for a sport bike, especially
a very fast one.
Cruiser - A type of motorcycle with a laid-back,
feet forward, seating position. A Harley-Davidson is the classic
example of a cruiser. Cruisers are generally large, heavy, bikes
with low seats. They are usually decorated with chrome. Examples:
Harley-Davidson, Indian, Kawasaki Vulcan, Honda Shadow.
Cubic Centimeters - Also called CCs. This is the
most common measure of engine displacement or "engine size" used
in motorcycling.
Cubic Inches - Measure of engine displacement (engine
size) that is used by some aftermarket Harley manufacturers instead
of CCs (cubic centimeters). Cubic inches are larger than cubic centimeters,
and are thus used mostly to describe engines of larger displacement.
A cubic inch is equal to 16.393 cubic centimeters.
Return to Top.
Damper - Commonly used term to describe a steering
damper, also can be used to describe a shock absorber.
Damping - The function of a shock absorber is called
damping. Damping is the removal of energy from the suspension system.
Desmo - Slang for a desmodromic engine.
Desmodromic - A type of engine which is unique
to Ducati. Rather than using a camshaft to open the engine valves
and springs to close them, a Desmodromic engine has no springs.
It has two sets of cams: one to open the valves and one to close
them. A desmodromic system has an advantage in that it does not
suffer from valve float and is mechanically more efficient than
a traditional system. However, it has a disadvantage in that it
requires more maintenance.
Desmodue - A two-valve desmodromic engine.
Desmoquattro - A four-valve desmodromic engine.
De-tune - The process of modifying a motorcycle
or engine so that it is slower than it might otherwise be. This
is done to customize a given motorcycle to certain track conditions,
to meet emissions or noise requirements, or to prep an otherwise
dangerous bike for a beginning rider.
Disc Lock - A lock that can be attached to the
brake disk on a bike as an anti-theft device. With the disk lock
in place, it is impossible to ride the bike becasue the front wheel
cannot rotate. However, it is still possible to lift up the bike
and place it in a truck, etc.
DOT-legal - refers to tires and helmets tested
and approved by the federal government for public road use. Also,
DOT-approved.
Drag - Short for "drag racing". In drag racing,
drivers complete to race a short, straight, track (usually 1/4 mile)
in the shortest possible time.
Drop a Bike - To have a low speed, single vehicle,
noncollision accident on a bike. A rider can literally drop the
bike by letting go of the handles while walking the bike. Can also
happen if the rider loses balance at slow speed.
Dropping the Clutch - The process of releasing
the clutch very quickly, usually while revving the engine. While
usually an accident, this is sometimes done on purpose when performing
a burnout or stunt, such as a wheelie.
Dry Sump - A type of engine in which oil is pumped
away from engine components as quickly as possible. It is an expensive
system that is generally used on racing engines only.
Dry Clutch - A motorcycle clutch that is NOT encased
within the engine and is NOT immersed in oil. They are generally
only used on racing motorcycles. Dry clutches have somewhat better
mechanical characteristics than the more common wet clutch, but
they are also noisy and more prone to rusting.
Dry Weight - Weight of a motorcycle without fuel,
oil, radiator coolant (in liquid cooled bikes) or rider. This is
the most consistent measure of weight of a particular model of motorcycle,
because it leaves out variable weights. This is the weight most
generally quoted in motorcycle advertisements and reviews. This
is the weight of a bike that has just come off of the assembly line.
Dual-purpose - A class of motorcycle that is intended
for both street riding and off-road. Like a dirt bike, dual-purpose
bikes have soft suspensions and large, knobby tires. Dual-purpose
bikes also have lights, turn signals, and other equipment required
for use on the road.
Duc - Slang term for a Ducati motorcycle.
Dynamometer - Also called a dyno. A large,
expensive, computerized device used for performance testing. Measures
the torque and horsepower at the wheel. To use the dyno, the drive
wheel is set in the valley between two calibrated rollers, and the
driver "accelerates" at the bike's maximum performance.
Return to Top.
ECU Chip - The computer chip that controls the
fuel injection system.
Only found on fuel-injected bikes. Short for Electronic Control
Unit, or Engine Control Unit. Aftermarket ECUs are available to
change the fuel mapping of many bikes.
Engine Braking - The process of downshifting into
a lower gear and lowering the throttle in order to use the natural
drag of the engine to slow down.
Exhaust Pipes - see Pipes.
Return to Top.
Face Shield - The clear part of the helmet.
Fairing - A fairing is a decorative and aerodynamic
"shell" that is usually found on sport bikes. Fairings are ususally
made of plastic or fiberglass. Also called Bodywork.
FIM - Federation Intermationale de Motorcyclisme.
A prominent motorcycle-sports sanctioning and safety body, headquartered
in Switzerland. on the web, in English, at http://www.fim.ch/en/
Fishtail Pipes - A type of exhaust pipe found on
some cruisers in which the end of the pipe has been shaped to resemble
a fish's fin.
Floorboards - The flat plate connecting the seat
and rear suspension and the front suspension of a scooter. Also
where the rider rests their feet.
Flyscreen - A steep, smaller than normal windscreen.
Flywheel - A metal disc attached to the crankshaft
in an engine.
It's purpose is to store energy (inertia) to keep the engine running
in between the firing of the individual cylinders. On many engines,
the flywheel doubles as a gear wheel for an electric starter motor.
Footpegs - see Pegs.
Foot-pound - A measure of torque equivalent to
one pound of
force applied tangentially at a radius of one foot away from an
axle.
Fork - The front end of a motorcycle. The fork
starts near the handlebars.
It is usually a pair of shock absorbers which go on either side
of the front wheel. The front brakes, etc, are secured to the forks.
Fork Cartridge - The portion of the fork that carries
the damper.
Fork Tubes - An individual part of the Fork. Two
fork tubes make up the fork.
Four-stroke - Type of motorcycle engine that runs
on normal gasoline, like a car engine. Four stroke engines are used
in most motorcycles, except dirt bikes.
Frame - The main "chassis" of the bike. All the
other parts of the bike such as the engine, seat, suspension, etc.
are mounted to the frame.
Frame Spar - One of the long members of the frame,
in between the frame joins.
Fuel Injection - Fuel injection systems are replacing
carbueretors on modern motorcycles. Also called EFI (electronic
fuel injection) systems, this is a computerized device that sprays
a finely atomized, precisely measured amount of fuel directly into
the cylinder intake ports in the engine. They are more reliable,
more predictable, and capable of higher performance than carburetors.
Fuel Mapping - Determines the richness of the fuel-air
mixture at different RPMs. This is what the ECU does in electronic
fuel injection.
Fuel Rail - A straight metal pipe which is directly
mounted to the fuel injectors on some fuel injected engines.
Furred - A bike that has been covered with fake
fur. This was started by a group of stunt riders in California.
In addition to being eye-catching, the fur conceals minor scrapes
and dings that develop on stunt bikes. Most riders consider this
an eyesore. Also called a fur job.
Return to Top.
Get-off
- To leave a bike deliberately in an emergency. Done so that the
rider can avoid a violent collision, and allows the leathers to
absorb the heat and abrasion of a slide. The leathers are meant
to absorb this damage. A get-off is much preferable to many types
of impact crashes.
This also lets the rider get free of the bike so that the risk of
crushing injuries is reduced. A get-off is also sometimes more controllable
than an impact.
Gravity Feed - A pump system that relies on the
action of gravity to feed materials to their destination. There
is no mechanical pumping needed with a gravity feed. Funnel, siphon,
and hopper systems are gravity-feed systems. Must be mounted vertically,
and must be designed to handle acceleration.
Gixxer - Slang term for a Suzuki GSX motorcycle.
GP Shifter - A shifter setup on a motorcycle that
is opposite the normal shift pattern. With a GP shifter, the rider
presses down to go up a gear and pulls up to go down a gear.
Return to Top.
Handlebar Risers - A part which is used to raise
the handlebars on a motorcycle higher up. This is done to change
the seating position or to change the look of the bike. Becasue
handlebar risers can upset the carefully designed steering geometry
on sport bikes, they are usually used on cruisers, where steering
geometry precision is less critical.
Hard Bags - Motorcycle luggage that is made of
plastic, fiberglass, or metal. Hard bags (Hard luggage) are more
durable than soft luggage. They are usually installed on Touring
bikes.
Hayabusa - Brand name for the Suzuki GSX-1300 motorcycle.
With a 1300-CC inline four cylinder engine, the Hayabusa is the
world's fastest standard production motorcycle, in a straight line
speed contest. (as of Feb. 2003)
Headshake - A violent side-to-side wobbling of
the handlebars and front end of a motorcycle. Also called a tank-slapper.
Heel/Toe Shifter - A device fitted on some cruisers
and touring bikes that uses the entire foot to shift gears rather
than just the toe.
Helmet - Protective headgear worn by motorcyclists
to protect the head during a crash. Helmets are available in three
types: Full helmets--which cover the entire head, Half helmets--which
cover the top of the head, but leave the face exposed, and 3/4 helmets,
which cover the head but have a visor which covers the face.
Helmet Roar - Noise heard inside some helmets at
freeway speeds. Caused by turbulence around the face shield and
other external edges. Can signal an ill-fitting helmet.
Highside - Type of motorcycle crash in which the
rider is flipped over the motorcycle. The highside is generally
regarded as one of the more dangerous types of crashes.
Highway Bars - A secondary set of foot pegs installed
on crusiers. Highway bars fit further forward, and sometimes higher
on the bike. When the rider gets up to speed on a long drive, he
can transfer his feet to the highway bars for a more comfortable
ride. Highway bars sometimes do not have controls (gear shift, brake)
on them, so the rider has to switch his feet back to the regular
pegs for slowing down. Also called Highway pegs, Freeway pegs, and
Freeway Bars.
Hill Climb - A type of motorcycle competition in
which the goal is to climb a very steep hirt hill as quickly and
as highly as possible. Drivers use modified dirt bikes to compete.
Hog - Slang term for a cruiser, especially a Harley-Davidson.
HOG - Harley Owners Group. An organization with
many local chapters which is both a fan club and riding group.
Homologation - The process of registering a product
or model of bike with a race sanctioning authority. This process
normally involves proving that the manufacturer offers the product
for sale to the public.
Horsepower - A measure of engine power. Originally
meant the amount of work done by a horse in one hour. 1 horsepower
equals 746 watts, in classical physics terms. Some small sportbikes
and standards may produce 40-50 horsepower. A modern superbike may
produce 150 horsepower if tuned properly, which is 1 horsepower
for every 2-3 pounds of dry bike weight! Horsepower must be measured
with respect to a certain RPM, and sometimes manufacturers will
advertise that their bikes produce, say, 120 HP at 7900 RPM. The
RPM in these measurements is usually the RPM at which the engine
produces the greatest HP. Horsepower can also be calculated directly
from torque, if you know the RPM, with this formula: HP = (Torque
* RPM)/5252
Hugger - This is a plastic, metal, or composite
fender that fits very closely around a tire on a motorcycle. It's
purpose is to prevent road debris from being thrown onto the bike
or the rider. Also called a mudguard.
Return to Top.
Ice Tires - Motorcycle tires designed for riding
on ice. They are modified dirt bike tires that have hundreds of
sharp metal studs set into the tread. Homemade ice tires may have
screws driven through the tire carcass and sealed into place.
Inverted Fork - Fork that has the damper in the
top section of the fork, as opposed to the classic fork, where the
damper cartridge is in the lower section.
Return to Top.
Jersey Barrier - A standard, 6-foot long, 3 foot
high crash barrier made of concrete. It is wedge-shaped and thicker
at the bottom, and has a rectangular top section. They are pre-cast
with forklift/rain drains in the bottom. Much friendlier than Armcos
to the biker, unless they have attachments embedded in the tops.
Jockey Shifter - see Suicide Shifter.
Jugs - Slang term for cylinders in an engine, especially
in a cruiser context.
Return to Top.
Kick Stand - A swing-out "leg" which is used to
stand up the motorcycle while parking. It is retracted for riding.
Kick Start - A means of starting the engine on
some older motorcycles. A kick starter is a lever, usually on the
right side of the bike, which the rider must swiftly "kick" downwards
in order to start the engine. When not in use, the kick start lever
folds up out of the way.
Knee Sliders - External plastic armor on racing
pant knees, facing the side of the knee opposite the bike. Used
as replaceable abrasion armor for "resting" knee on road during
tight turns. When in a tight turn, sportbikes can be leaned over
so much that the outside of the knee is used to steady the bike.
Knobbies - Slang term for the tires used on dirt
bikes and trail bikes.
The tires have large knobs that make up the tread, hence the term
knobbies.
Knocking - Detonation of the fuel-air mixture before
the spark plug fires.
Caused by overheating engines or low octane gas. Not healthy for
your engine. Also called pinging.
Knock Sensor - A knock sensor is a little microphone
that is fitted into the engine block. It literally "hears" knocking
and pinging. Upon this happening, the ECU will retard the igntion
timing in order to prevent knock.
Return to Top.
Lacing
- Process of installing spokes on a spoked wheel or rebuilding a
spoked wheel. Most common in a dirt bike context.
Lap Counter - Device installed on racing motorcycles
that tells the driver how many laps have been completed since the
counter was last reset (usually at the beginning of a race).
Leadwing - Derogatory slang for a Honda Goldwing,
especially one that has been heavily customized with luggage or
other heavy, bulky accessories.
Lean Mixture - An air/fuel mixture that has relatively
little fuel in it.
Leathers - Protective leather clothing worn by
motorcyclists, especially racers. Leathers are available in pants,
jackets, or 1-piece suits that cover the entire body.
Linked Braking - Braking systems that activate
both front and rear brakes, in preset ratios, with the pull of one
brake lever.
Liter-class Bike - A racing bike that has an engine
displacement of 1000cc.
Low-end - The first third or so of the rev range
of a bike. This is where acceleration and torque are important factors.
Lowside - A type of motorcycle crash in which the
rider falls down, off the side of the bike closest to the ground.
Lowsides are among the less severe crashes.
Lugging - When the transmission is in a higher
gear than needed and the engine doesn't have enough power to drive
smoothly, it "chugs" or "lugs" along. May occur for three reasons:
not giving the engine enough gas or letting the clutch out in a
non-smooth manner when starting out from a stop, or driving in too
high of a gear.
Lung - Slang term for cylinders in an engine. A
single cylinder engine is commonly called a "1-lung motor".
Return to Top.
Master
Cylinder - The small hydraulic cylinder that is sqeezed
by the rider's hand in a hydraulic brake or clutch system. The master
cylinder generates the pressure which activates the brakes or clutch.
Master Link - A link in a motorcycle chain that
is removeable.
Removing the master link allows the chain to be easily removed for
cleaning or adjustment.
Midrange - The middle third or so of the rev range
of a bike. This rev range is important for freeway cruising, and
other normal on-road travel.
Mill - Slang for the engine.
Monoposto - Italian for "single seat."
Motocross - A type of motorcycle racing that simulates
off-road conditions. Motocross tracks are made of dirt and have
hills, jumps, and tight turns. A motocross bike is a dirt bike intended
for motocross competition. They are not street legal and have extremely
long-travel suspension for taking large jumps.
MSF - Motorcycle Safety Foundation. The premier
organization dedicated to making motorcycling safer. Brings you
the Motorcycle Safety Course. We absolutely recommend taking the
MSF safety course before buying a bike or getting your license.
We wholeheartedly recommend taking this course, even if you didn't
get a discount on your insurance, which will pay for the course,
anyway. After you have experience, we recommend that you take the
Advanced Course, too.
On the web at: http://www.msf-usa.org/
Return to Top.
Naked Bike - A motorcycle in which the frame and
internal parts are openly visible. Examples include the Yamaha FZR,
Ducati Monster, and Honda 919. Many naked bikes are simply sport
bikes with the fairings removed, or abbreviated. While many cruisers
are technically "naked bikes", the term usually refers to sport
bikes.
Nitro - Slang for "nitromethane". Nitromethane
is a highly potent fuel used in drag racing applications.
Nitrous Oxide - A chemical, N20, which is injected
into the air intake of an engine to give a momentary boost in power.
Nitrous oxide contains more oxygen per unit volume than does normal
air, which allows an engine to burn more gasoline than it normally
could, producing more power. Nitrous oxide systems are sometimes
installed on drag race motorcycles.
NOS - Slang term for Nitrous Oxide. Also, the brand
name of a major company that sells nitrous oxide related hardware.
Return to Top.
Official Interview - Slang for being pulled over
by a police officer.
Oil-pickup Cavitation - Cavitation is turbulence
in fluid flow. Oil pickup cavitation occurs when, due to geometric
factors, the oil flow into the oil pump in an engine is disrupted
due to turbulence.
On the Bottle - Slang for actually using a nitrous
oxide system. Nitrous oxide is stored in pressure bottles, hence
the slang.
Open-class - The class of motorcycle racing with
the least restrictions on the motorcycle features, performance,
and sometimes, engine size. Also used to describe the motorcycle
itself.
Original Equipment Manufacturer - A part made by
the manufacturer that supplies the part to the motorcycle manufacturer.
Often, a part made to these exact specifications.
Oversquare - An engine that has a bore diameter
longer than the stroke. These engines tend to produce lots of horsepower
at the top end at the expense of low end torque.
Oxygen Sensor - An exhaust part that measures the
proportion of oxygen in the exhaust gases. Used to determine if
the fuel/air mixture is too lean or too rich. Communicates this
information to the ECU, which changes the mixture accordingly. Also
called a lambda sensor.
Only found on fuel injected engines.
Return to Top.
Paddle Tires - Type of tire that is smooth except
for several large, cup-shaped rubber paddles that are affixed to
the tire. It is useless for any purpose except riding on sand or
loose dirt. Paddle tires are only used for riding on sand dunes
or hill climbing competitions.
Panniers - A type of luggage that consists of two
bags, one mounted on each side of the rear end of the bike. Also
called saddlebags.
Parallel Twin - A two cylinder motor where both
cylinders share the same angle with respect to vertical. They are
in line with each other.
Pegs - Objects on which the rider of a motorcycle
puts his feet. The passenger generally has their own set of pegs.
The pegs protect the feet and place them close to the controls.
Performance Award - Slang for a speeding ticket.
Petcock - A valve which controls the flow of gasoline
in older carbureted bikes. It is mounted at the bottom of the gas
tank. The petcock must be turned to "run" in order for fuel to be
delivered to the engine. Petcocks also have an "off" position which
is used when the bike is parked.
Pig - Derogatory slang for a police officer. Also:
Bacon.
Piggyback Shock - A type of shock absorber that
has a seperate reservoir of oil or gas which is mounted to the shock
itself. Piggyback shocks are higher performance shocks compared
to standard shocks.
Pillion - The rear (passenger) seat on a motorcycle.
Pipes - Exhaust pipes are often customized in order
to change the appearance, sound, and performance of a motorcycle.
Typically when someone is talking about "Exhaust pipes" in a motorcycle
context, what they are acutally talking about is the mufflers.
Points - A type of igniton system found in carbureted
engines. Points are electrical contacts (similar to switches) which
are activated by the camshaft. These contacts fire the spark plugs
at the correct time to make the engine run properly.
Poppets - British slang for valves
Power Valve - Marketing term for a variable-size
exhaust port installed in two stroke engines, usually found on dirt
bikes. By changing the size of the exhaust port, more power can
be extracted from the engine.
Pots - Slang term for a piston in a brake caliper.
One might say "I've got four-pot calipers up front".
Preload - A suspension term that indicates the
amount of load a suspension spring is under with no rider on the
motorcycle. It ususally applies to the spring on the rear shock
absorber. Increasing preload has the effect of making the suspension
"harder" and can increase ride height slightly. Decreasing preload
has the opposite effect. On most bikes preload is adjustable.
Prestressed Member - Engineering term that refers
to how a portion of the bike's frame is designed. A prestressed
memeber is something that is normally under a load in the opposite
direction that it might experience during use. Thus, any loads incurred
during riding actually LOWER the forces on the prestressed part.
Many times, the engine casing is an integral part of the bike's
frame, and may be a prestressed member.
Privateer Racing Team - A racing team not sponsored
by a major manufacturer. Sometimes means a team not receiving the
majority of its sponsorship money from any one company. Not a specific
racing team, but a type of racing team.
Progressive Suspension - A suspension system, ususally
on the rear of a motorcycle, in which the spring rate changes as
the suspension compresses.
Pullback Bars - Standard handlebars used on cruiser-type
motorcycles. Designed to be accessible from a laid-back seated position,
but not too extreme.
Pyrometer - Fancy name for a thermometer that is
set up to measure the the temperature of the exhaust gas leaving
an engine. It is usually an electronic thermometer (thermocouple).
Return to Top.
Quarter-fairing - A section of a fairing on a sportbike.
A smaller-than-normal fairing on a sportbike.
Return to Top.
Rainbow Titanium - A type of metal finish that
can be applied to titanium, which gives it a rainbow-colored appearance.
Rake - The angle of the fork with respect to vertical.
Ram-air - To use a ram-air system is to use the
natural pressure increase at the front of the bike due to forward
motion to push more air per stroke into the cylinder head.
Rat Bike - A motorcycle bought and maintained as
cheaply as possible; generally looks the part.
Rearset - On a sportbike, the rearset consists
of the foot pegs, gear-shift and rear brake levers, and the associated
brackets which hold them to the frame. Also describes the position
of the pegs on a sportbike, as in "rearset pegs."
Rebound Damping - The damping provided by a shock
absorber as it extends or "rebounds", such as encountering a dip
or pothole, or recovering from compression.
Redline - Fastest recommended RPM for an engine.
Denoted by the start of the red area on the tachometer. Also, the
optimum point to shift gears, in performance driving.
Reed Valve - One-way valve installed in the air
intake on a two-stroke engine. It's purpose is to increase efficency
by reducing the tendency of the engine to blow fuel-air mixture
back out the intake.
Reserve Tank - Some motorcycles have fuel tanks
that are partitioned, with the smaller portion available to the
engine only by turning a valve. The smaller portion is the reserve
tank.
Rev - Slang for revolution. Also, to increase power
to the engine without using it. Can be done to warm-up the engine
(not healthy for the engine to be warmed up this way), or to show
off.
Rev Limiter - An electronic or mechanical device
that limits an engine to a certain range of RPMs. Used to limit
the speed of the engine to avoid damage, or to meet legal and environmental
restrictions.
Rev Range - This is the range of RPM over which
an engine is useful. >From idle to redline.
Rice Burner - Slang term for any Japanese motorcycle,
especially Japanese sport bikes.
Rice Rocket - see Rice Burner
Rich Mixture - An air/fuel mixture that has a relatively
large amount of fuel in it.
Ride Height - see Seat Height.
Riding Position - Refers to the shape of your body
when properly driving a motorcycle. There are upright, laid back,
and racer-type positions. Usually depends on type of bike. Standards,
touring, and cruisers have either an upright position, where you
are sitting as at a desk, or laid back position, where you are sitting
as in a recliner. Sportbikes generally have a racer-type or tuck-type
position with knees close to the chest, and the gas tank helps to
support the chest.
Road Rash - Slang for the injuries resulting from
sliding down the road in an accident. Scrapes, abrasions, and other
sliding damage as the result of an accident. Can be severe or deadly.
Rocker Arm - A bridge connection set on a pivot,
that connects the camshaft to the intake and exhaust valves. Opens
the valves when pushed on by the cam lobe. Also called rockers.
Rolling Chassis - Those parts of a bike making
up the suspension system, wheels, and frame.
Rotors - A rotor is the disc part of disc brakes.
It is a wheel-mounted metal disc. During braking, the brake calipers
clamp onto this disc, slowing and stopping the spinning of the wheel.
Return to Top.
Saddle
- Another word for a motorcycle seat. Since the body of the bike
is normally between the legs, sitting on a motorcycle is more like
sitting on a horse than on a seat.
Seat Cover - The material that protects the seat
from wear.
What you sit on. Can be leather or any other durable material.
Seat Height - Measurement of the distance between
the ground and the lowest point of the seat on a motorcycle. Cruisers
generally have very low seat heights, followed by standards and
touring bikes. Sport bikes tend to have taller seat heights. Dirt
bikes have very tall seat heights, due to their need for extreme
suspension travel.
Seat Pan - The base of a motorcycle seat, on which
foam or other cushioning material rests. The seatcover is usually
attached to the edge of the pan.
Shaft Drive - A type of motorcycle drive system
in which the engine is connected to the rear wheel by means of a
drive shaft as opposed to a chain. Shaft drive systems require less
maintenance than do chain driven motorcycles. However, shaft drive
is less efficent. Shaft drive systems are generally used on cruisers
and touring bikes, where reliability is prized above absolute efficiency.
Shark Guard - Metal bracket used to protect the
chain and sprocket on dirt bikes. It is called a "shark guard" becasue
they are usually shaped like a sterotypical shark's fin.
Shower-type Injector - Type of fuel injector that
sits as far out in the intake tract as possible. It releases a gentle
"shower" of gasoline into the engine. This is different from the
standard fuel injector which sprays a fine jet of gasoline into
the cylinder directly.
Silencer - Another term for the muffler. See Pipes.
Single Pin Crank - Type of crankshaft that has
only one offset journal.
All single-cylidner engines have single pin cranks. Some twin cylinder
engines have single-pin cranks--meaning that both connecting rods
(and therefore both pistons) connect to the same point on the crankshaft.
This is what is responsible for giving Harley-Davidson motorcycles
their unique sound--though it is also very common among other V-twin
engines as well.
Sissy Bar - A kind of backrest installed on cruisers.
Sled - Slang term for motorcycle.
Sleeved Engine - Most motorcycle engine blocks
are made from Aluminum. Aluminum, though light and strong, does
not have sufficent wear resistance to make good cylinders. Therefore,
a sleeve (tube) made of cast iron or other wear resistant metal
is inserted into each cylinder. The actual cylinder bores, therefore,
are the interior of these sleeves.
Slicks - Racing tires that are smooth and without
tread. Slicks offer superior traction on the smooth, clean, concrete
of a race track.
Sliders - A pair of plastic pegs that are mounted
to the sides of a sportbike. Their purpose is to protect the bike
from damage if it is crashed during a race. The slider will strike
the ground first, preventing damage to the rest of the bike.
Slip-fit - An engineering term for a type of coupling
that holds two or more parts together. A slip-fit joint is one in
which one piece slides inside the other and is then secured. In
motorcycling, slip-fit joints are often used for exhaust components.
Slip-ons - Slang for aftermarket mufflers.
Slipper Clutch - Type of clutch that is primarily
used on high-performance motorcycles and in road racing applications.
A slipper clutch works like a normal clutch, except that if the
rear wheel is attempting to overspin the engine (such as when downshifting
or "engine braking"), the clutch will partially disengage ("slip")
and the bike can coast to a large extent, without having to release
the clutch manually. This allows for faster downshifting in competition.
It can also be a safety device becasue it can prevent the rider
from loosing control during a sudden or improperly executed downshift.
A slipper clutch makes it impossible for the rear wheel to lock
up if the engine stalls or siezes.
Slugs - Slang for pistons.
Side Car - A device that can be attached to some
motorcycles in order to carry luggage or a passenger. It mounts
to one side of the bike (usually the right side) and contains a
seat for the passenger. There is a wheel on the far side of the
sidecar which rolls along the road, making a sidecar-equipped bike
a three-wheeled vehicle.
Snell - Short for the Snell Memorial Foundation,
an organization which conducts safety tests on helmets. Snell Certification
requriements are more stringent than DOT requirements for helmets.
Therefore, it can be said that Snell-certified helmets are better
than non-Snell-certified helmets.
Soft Luggage - Motorcycle luggage such as tank
bags or saddlebags (panniers) that is made out of a flexible material
such as leather.
Spaghetti System - A type of high performance exhaust
system made with long, equal length headers. In order to maintain
the equal header length, the header tubes are folded back on each
other before meeting at the silencer(s). The long, winding tubes
look like spaghetti, hence the term. Spaghetti headers are very
high performing, but are generally very expensive.
Spark Plugs - Spark plugs are part of the ignition
system on a motorcycle engine. They screw into the cylinder heads,
and there is usually one per cylinder, sometimes two. The spark
plug is used to generate an electrical spark which ignites the gasoline
in the engine, producing power.
Sport Bike - A type, or class, of motorcycle designed
for high performance riding. Sport bikes generally have powerful
engines, excellent handling, and a "racing", or "tuck" style seating
position. Examples: Kawasaki Ninja, Honda CBR, Suzuki GSX.
Sport-Touring - A cross between a sport bike and
a touring bike.
They are generally based on the sport bike frame, but have additional
comfort features such as a large windscreen, luggage, and a less
extreme seating position.
Sprockets - A sprocket is basically a gear wheel
which is designed to mesh with a chain instead of another gear.
Sprockets are used in chain drive motorcycles. There is one sprocket
mounted to the rear wheel and another on the engine.
Sprung Weight - The weight of the motorcycle supported
by the springs or shocks.
Squid - Biker jargon for an irresponsible, dangerous,
rider. It comes from "SQUirrely kID".
Standard - The "original" type of motorcycle. Standards
have upright seating positions. They are generally smaller than
the average cruiser, and are much less "extreme" than sportbikes.
Example: Honda Nighthawk
Steering Damper - A mechanical device, similar
to a shock absorber, which is mounted between the front fork and
the frame on a bike. It's purpose is to cushion vibration in the
front end and to prevent sudden movements or headshake which could
casue the rider to lose control. On dirt bikes, steering dampers
are used to prevent loss of control if the front wheel of the bike
strikes a rock, depression, or other abnormality on the track.
Steering Head - The part of the frame that connects
to the fork and front suspension. Looks quite like a hinge. Also
just called the "Head."
Steering Head Bearing - The part of the steering
head that holds the triple tree, and facilitates turning of the
fork.
Steering Head Race - The part of the steering head
in which the Steering head bearing is seated.
Steering Lock - A device that immobilizes the steering
head, either in situ or at a pre-determined angle, when the ignition
and electrical systems are turned off. An anti-theft device.
Steering Stops - Part of the steering head that
limits the rotation of the fork and steering assembly.
Stock - Unmodified from factory condition.
Stoppie - A kind of stunt in which the rider brakes
very hard on the front wheel only, while leaning forward so that
the rear wheel of the bike comes off the ground as the bike slows.
Stroke - The distance that the pistons travel up
and down inside a motorcycle's engine.
Bore * stroke * number of cylinders = engine displacement
Stroked - see Stroker Stroker - An engine that has been
modified so that it has a longer than normal stroke. This is a means
of boosting the displacement and torque output of the engine.
Sub-frame - A frame structure on a motorcycle that
is made as a separate part that bolts onto the main frame. Generally,
this applies only to sport bikes. The seat assembly is the sub-frame
which mounts to the main frame.
Suicide Shifter - A type of shifter which is actuated
by hand rather than with the foot. It requires the rider to take
his hand off the handlebars in order to shift.
Sump - The lower part of the crankcase in an engine.
The sump is basically a tray or tub that collects the oil as it
circulates around the engine.
Superbike - A type of world-class racing competition.
Also a slang (and marketing) term for a top-of-the-line sportbike.
Example: Ducati 998
Supercharger - A type of air compressor that is
driven off the crankshaft of an engine by means of a belt, chain,
or gears. It's function is to raise the air intake pressure of an
engine, allowing it to produce more power. Superchargers are more
complicated than turbochargers, but do not suffer from "turbo lag".
Supermotard - A race combining street-style racing
with off-roading.
Requires a bike at home in both places.
Superslab - Slang for the interstate highways.
Swingarm - A major part of the rear suspension
on most motorcycles.
The swing arm is hinged to the frame near the engine. The other
end of the swingarm has the wheel mounted to it and moves up and
down a few inches. This movement is dampened by a shock absorber.
Swingarm Pivot - The part of the frame to which
the swingarm connects and rotates on.
Return to Top.
Tall Gearing - Refers to a final drive ratio (chain
or shaft gear ratio) which is numerically low. This results in a
bike which is slower to accelerate but will have a higher top speed
and lower cruising RPM. Tall gearing is good for gas mileage, top-end
speed, and decreased emissions (both noise and gaseous). Tall gearing
is poor for acceleration and can also make starting out from a stop
more difficult.
Tank Bag - A piece of motorcycle luggage. A tank
bag is usually made of tough cloth or leather, and straps to the
bike's gas tank. Sometimes used on sportbikes as a cushion for the
rider's chest.
Tank Bra - A pad, usually made of leather, plastic,
or rubber, that is placed on the back of a motorcycle's gas tank.
It's purpose is to prevent the rider's clothing (pants buttons,
belt buckle, etc. ) from scratching the paint on the tank. It can
also provide some additional comfort in extreme weather becasue
it insulates the rider's crotch from the gas tank.
Tank Skin - Slang for tank bra.
Tank Slapper - see Headshake.
Testastretta - Italian for "narrow head". It refers
to the latest generation Ducati motorcycle engine.
The Motor Company - Shorthand slang for The Harley
Davidson Motor Company. Harley is famous for their motors, especially
the sound of their motors.
Throttle - The throttle controls the speed and
power of the engine.
It is analagous to the gas pedal in a car.
Throttle Body - A throttle body is an air intake
valve (something like a carburetor) used with a fuel injection system.
Throttle Body Barrel - The cylindrical "tube" portion
of a throttle body.
It contains the throttle plate.
Throttle Lock - A device that can be used to lock
the throttle at a chosen setting while the bike is in motion. It
is designed to reduce hand fatigue on long trips. They are controversial
becasue in a critical sitation, they can make it more difficult
for the rider to slow the bike or more dangerous to swerve. They
are sort of a non-variable cruise control for bikes.
Throttle Plate - Part of a carburetor or throttle
body. This is a device that regulates the airflow into the engine,
and therefore the power output of the engine. It is a disc-shaped
plate that is mounted inside a tube.
By rotating the plate, more or less of the tube is open for air
to flow through.
Throttle Rocker - A device that attaches to the
twist grip of a motorcycle that allows the rider to use the palm/heel
of his hand to actuate the throttle. It is designed to be less fatiguing
than a standard twistgrip for long rides.
Tire Squirm - Instability in tires resulting from
the bending of the tall portion of the treads under torque. The
more tread lines a tire has, and the closer they are, the more tire
squirm you will get. A racing slick, which has no treads, has the
least amount of tire squirm.
Top Dead Center - The position of the crankshaft
at the maximum compression of the fuel-air mixture, and minimum
size of the cylinder cavity. The position of the crankshaft at the
end of the compression stroke and the beginning of the power stroke.
Usually measured from the number one cylinder.
Top-end - The last (highest) third or so of the
rev range of the bike, before the redline. This rev range is important
for getting the highest speed possible, as in drag racing.
Torque - The amount of rotational force generated
by the engine. Usually measured at the crankshaft, because the transmission,
sprocket size, and tire size change this value. This force is applied
through the transmission, chain, and rear wheel in order to move
the bike forward. Torque is measured in foot-pounds. Torque can
be calculated from horsepower with this formula: Torque = (HP*5252)/RPM
Torquey - Refers to a motorcycle that has lots
of low-end torque.
Touring - A motorcycle designed for long-distance
riding. Touring motorcycles are large motorcycles with many comfort
features, such as large padded seats, large windscreens, even radios.
Example: Honda Gold Wing.
Trail - The angle between the front end of the
bike, which rotates to allow steering, and the frame.
Trail Bike - A type of motorcycle designed for
recreational off-road riding. See Dirt Bike. Trail bikes have soft
suspension and knobby tires.
Transverse Mounted Engine - An engine mounted in
the bike so that the crankshaft is parallel to an imaginary line
running from the front to back wheel. The cylinders in a transversely
mounted v-type engine stick out from the frame a little. The arms
of the "V" are sideways to the direction of forward motion.
Triple Clamp - The triple clamp is part of a bike's
front end. It is a somewhat triangular shaped metal plate with three
large holes in it.
There are always a pair of these. One attaches at the top of the
fork, one attaches some ways down the fork. Two of the holes secure
the front forks. The third hole attaches the fork to the steering
pivot. When you turn a bike's handlebars, the triple tree is the
main part of the "hinge" you are turning. Also called Triple Tree.
Triple Tree - see Triple Clamp.
Truss Frame - A frame that uses many diagonal connecting
members to connect the frame spars, creating triangular sections
between the frame spars, which increases strength. Looks somewhat
like a bridge or a roof truss. Based on the engineering principle
that a triangle is a very strong shape that resists deformation
stresses.
Tuned Pipe - Type of exhaust pipe, installed on
two-stroke bikes, that has a specifically tuned volume and shape
to help maximize power from the engine. They are usually shaped
something like a "fat banana".
Turbo - Slang term for a turbocharger. Also, a
bike that is equipped with a turbocharger.
Turbocharger - A type of air compressor which is
driven by a turbine mounted on the exhaust of an engine. It raises
the pressure of the air intake, allowing an engine to make more
power. A turbocharger is somewhat similar to a supercharger. Turbochargers
are more efficent and less mechanically complex, but they suffer
from "lag", which is a time delay between when the throttle is hit
and when the extra power from the turbo is produced.
Turning Circle - The circle made by the front wheel
of a bike while turning in a complete circle.
Twistgrip - The most common type of throttle on
a motorcycle. A twistgrip throttle is controlled by rotating the
grip while holding onto it.
Two-stroke - Type of motorcycle engine that runs
on a mixture of oil and gasoline. Two stroke engines are usually
more powerful than four-stroke engines of the same size. Two-strokes
are commonly found only in dirt bikes. They are characterized by
their high pitched sound.
Two-up - A slang term that means riding with a
passenger.
Return to Top.
Unsprung Weight - The weight of a motorcycle not
supported by springs or shocks, i.e. the wheels, brakes, tires,
and most of the suspension.
Return to Top.
V-twin - A two-cylinder engine in which the cylinders
are arranged opposite each other, at an angle from, usually, 45
to 90 degrees.
This makes the cylinder block look somewhat like a V.
Valve Float - In a traditional engine, the valves
are closed by strong springs. When an engine is run at very high
RPMs, sometimes these springs cannot close the valves completely
or fast enough. This causes degraded performance at these high RPMs.
Return to Top.
Wet
Clutch - The most common type of motorcycle clutch. A wet
clutch is immersed in engine oil.
Wheelbase - There are three important distances
between the wheels and tires. The distance between the axle of the
front wheel and the axle of the rear wheel, the distance between
the front contact patch and the rear contact patch, and the minimum
distance between the tire edges. The distance between the front
contact patch and the rear contact patch is the wheelbase. The wheelbase
affects the diameter of the turning circle.
Wheelie - A kind of stunt in which the rider accelerates
very hard while pulling back on the handlebars so that the front
wheel comes off the ground.
Windblast - The buffeting and noise felt at high
speeds due to the wind.
It can usually be controlled with a windscreen or taller fairing,
or a more tucked riding position.
Return to Top.
