Top 120 Non-vulgar Motorcycle Terms

’48 H-D Panhead:  First year H-D Panhead for sale by the road.
’48 H-D Panhead: First year H-D Panhead for sale by the road.

As with many highly specialized art forms, motorcycling has a language all its own. Perhaps most bewildering to non-riders, new riders or riders like me who just don’t get around too much, are some of the technical and slang terms in use.

You may be familiar with many of these terms, but there may be a few you’ve heard but aren’t sure about or have not heard at all. We hope you will find this brief glossary of terms helpful when you hear some of them thrown about among motorcyclists when they gather.

Not included are those four-letter and hyphenated terms that often are uttered when mechanical failures and other such maladies occur; besides, you know those already.

Top 120 Non-Vulgar Motorcycle Terms:

Aftermarket: Motorcycle parts manufactured to replace original equipment parts.

Amal: A brand of carburetor typically seen on vintage European bikes.

Ape hangers: Handlebars which put the rider’s hands in the “reach for the sky” position.

Bagger: A bike set up with saddlebags and usually with other touring accessories.

Balancer: a chain or gear-driven shaft with an off-set counterweight that cancels vibration generated by the action of the engine. Also called a counterbalancer.

Barn find: The term used to describe finding a classic or true rare collector bike literally in a barn, shed or at a farm/estate auction.

BDC: Bottom dead center; the point where the piston is at the bottom of its stroke.

Belt: Typically a cogged Gilmer drive belt for timing, primary or final drive. Or that thing helping those suspenders keep your jeans from falling down.

Beeza BSA advertising
“Beeza” : BSA’s own 1969 advertising slang for its brand name. Some readers may not have noticed there’s also a motorcycle in this full page ad.

Beeza: Sixties marketing slang for “BSA.” (See image—they don’t make motorcycle advertising like this 1969 full-pager anymore…)

Beezumph: A hybrid made with a BSA and a Triumph.

Bing: No, not the crooner half of Hope and Crosby; it’s a brand of carburetor.

Blockhead: Nickname for the Harley-Davidson Evolution engine design introduced in late 1983. So named because, well, you know; just take a look. Also applicable to riders (of any brand) who think public roads are race tracks and drag strips.

Blower/blown: Supercharger equipped as in the recent Kawasaki H2/H2R.

Bobber: A custom with cut-down or “bobbed” fenders and other modifications, though not as radical as a chopper.

Bore: The diameter of the engine cylinder. (See also: stroke). Also, yokels who insist on telling you five times about the Rapido they had in high school.

Café: Some think this is a place to eat. Actually, it is a bike typically fitted with clip-on or clubman handlebars, long, racer-styled fuel tank, single saddle and rear-set footpegs and controls, minimal or no fenders, all to imitate the look if not the performance of classic road racing machines.

Cages: Non-motorcycle vehicles with which we must share the road.

CDI: capacitive discharge ignition; an electronic ignition system.

CE: Stands for Certification Europe. These sets of standards apply to a wide range of things, including protective motorcycle riding gear such as impact protectors, boots, gloves and helmets. Look for “ECE” (Economic Community Europe) 22.05 certification on helmets that have met that standard.

Choke: a mechanism or plate used to limit air intake to the fuel system to “enrichen” or increase fuel in the mixture sent into the engine by the carburetor during starting and warm-up. Also, what motorcyclists want to do to the guy who invented carburetors when trying to start their bike on a cold morning.

Chopper: A radically styled custom with long, kicked-out forks up front, wild handlebars, low seat, one-off paint and minimal safety gear. Considered an art form by some; a waste of an otherwise good motorcycle by others.

Clip-ons: Handlebars typically used on café-racers and racing bikes that attach to the fork legs.

Clocks: British motorcycle slang for the motorcycle’s instruments.

CV: stands for “constant velocity” a later version of carburetor design and also may refer to a type mechanical joint in a drive system.

Damper: A device that can be used to control steering motion (steering damper) or the rebound action of a compressed spring.

Desmo or desmodromic: a gear driven valve actuation system pioneered by Ducati. Desmo is also the name of a cool helmet by France’s Roof Co. For more, visit Ducati Desmo.

DOT helmet certification emblem required on helmets for on-road use in the U.S.
DOT helmet certification emblem required on helmets for on-road use in the U.S.

DOT: U.S. Department of Transportation federal helmet safety performance standard (formally FMVSS 218) for road-going helmets. Read more on helmet safety standards.

Dresser: Slang for “full dress” or fully equipped touring bike.

Duc: Slang for Ducati. Not to be confused with Duke five cylinder axial engines. For more, visit Duke engines.

ECE: Economic Community Europe. The ECE prefix applies to standards used for testing helmets sold in European markets. Also the root for CE armor used in riding jackets. ECE 22.05 refers to the CE standard that applies to motorcycle helmets. For more on helmet safety standards, see DOT above.

ECM: Engine control module. Also ECU or engine control unit.

EFI: Electronic fuel injection. Not to be mistaken for “IFFY” which is the term frequently applied to the Lucas electrics on vintage Brit bikes.

Evo: Slang for the Evolution engine Harley-Davidson introduced in 1983.

Electrode: The tips between which the spark occurs in a spark plug.

Expansion chamber: An exhaust system for a two-stroke engine that can, when properly designed, increase engine performance. When not properly designed, it actually cuts performance but still makes a lot of noise.

Fairing: Bodywork made out of fiberglass, plastic, carbon fiber or other light material intended to improve aerodynamic performance and/or provide some weather protection for the rider.

Featherbed: A patented chassis design on certain Norton motorcycle models, starting in 1952. The design is still prized by vintage Norton fans to this day. The last models with the Featherbed frame were produced in 1970.

FIM: Federation Internationale de Motorcyclisme. The European equivalent of the AMA. See: www.fim-live.com/en/

Flathead: an engine design where the head over the cylinder does not include intake or exhaust valves.

Float: A device in some types of carburetor that literally floats in a bowl of fuel inside the carburetor. The float controls a valve that regulates fuel in-flow. Usually the only time you’re aware your carburetor has a float is when it doesn’t.

Four-stroke: (also referred to as four cycle) a type of engine that has a four-part power cycle; intake on a down stroke, compression on the ensuing upstroke, power on the down stroke and exhaust on the ensuing upstroke.

Gaiter: A rubber or neoprene cover over the tube of a telescopic fork to prevent dirt from getting on the slider surface.

Gap: No, not a store for fashionistas—this is the space between electrodes of a spark plug or the contact surfaces of breaker points.

Girder fork: Front suspension unit designed with a frame supporting the front wheel and the entire frame either rigid (no springing) or using a pivot with coil or leaf springs to provide some suspension. Most common on machines built up to and shortly after World War II.

Gixxer: Slang for Suzuki GSX-R models.

Gyroscopic precession: Gyroscopic force that causes a spinning wheel to allow countersteering and to be self-centering.

Helical gears: Gears that typically mate in such a way as to change the direction of a drive train by 90 degrees and the gear teeth are cut in a spiral pattern. Often found in the rear drive unit of shaft drive motorcycles.

High-side: Not to be confused with “up side” this is a form of motorcycle get-off where the bike tosses the rider in retribution for letting the rear wheel slide sideways only to regain traction. It is the evil twin of the “low-side” where in the tires lose contact with the tarmac during extreme cornering and the bike goes full-horizontal.

Hydraulic: A system of transferring force using an incompressible liquid; typically in disc brake systems and the clutch activation system in some models. Also, the use of fluid to provide damping in suspension or steering systems.

Isolastic: The trademark name given to the suspension system used on the Norton Commando models starting in 1967. The engine and rear swingarm had rubber mounting points to isolate the rest of the frame from engine vibration. For more, visit Norton Commando history.

Jam nut (also lock nut or stop nut): A second nut tightened down over a fastening nut to help keep the first nut from vibrating loose.

Jampot: Slang for the large diameter shock absorbers on some Brit bikes in the 1950s.

Jet: A small hole in the body of a carburetor that, with the addition of a jet needle helps to control the precise metering of fuel into the engine.

Kadency effect: The use of pressure wave behavior to enhance fuel filling and exhaust gas scavenging in the engine cylinder head.

1936 Knucklehead at WTT:  A sweet example of a Harley-Davidson knucklehead on display at Wheels Through Time museum.
1936 Knucklehead at WTT: A sweet example of a Harley-Davidson knucklehead on display at Wheels Through Time museum.

Knucklehead: Nickname for the head design introduced by Harley-Davidson in late 1936, so named because the rocker covers resemble big knuckles of a clenched fist. Also popular nomenclature for riders who think they know how to ride fast in a crowd—but don’t. For more, visit Harley Knucklehead.

LCD: Liquid crystal display—system for digital instruments.

Leading link: A type of front suspension system similar in operation to the swing arm and shock absorber arrangement common to the rear suspension of most motorcycles.

Leading shoe: In older internal expanding shoe drum-style brake systems, this refers to the actuating cam being on the leading edge of the brake shoe. There can be single or double leading shoe drum brake configurations.

Magneto: A device using copper wire windings and magnets that generates electrical current when it rotates.

Map: Code used by the ECU to make the magic happen. Also a quaint paper item that never gets folded the same way twice with roads printed on it now being replaced by a gizmo called “GPS.”

Non-unit construction: (Also referred to as “pre-unit”) where the transmission and engine are not assembled as a unit and do not share a common case; the transmission is entirely separate from the engine. This distinction is often heard in reference to early Triumph motorcycles—those being built before 1963 as “pre-unit” when Triumph used separate engine and transmission, and “unit construction” after 1963 when the engine and transmission were built as one.

Normally aspirated: An engine fed by a fuel system using atmospheric pressure without the pressure boost of a turbocharger or supercharger.

Norvin: Name given to a hybrid Norton and Vincent.

Octane: The rating of antiknock properties of fuel based on a comparison of fuels comprising iso-octane with a rating of 100 and heptane, with a rating of zero. The volumetric percentage of iso-octane is taken as the octane rating of the fuel.

OHC: Overhead cam (shaft)—engine configuration with the camshaft(s) located on top of the cylinder heads. Can be single overhead cam (SOHC) or double overhead cam (DOHC).

OHV: Overhead valve—engine configuration with valves located over the cylinder heads, but the camshafts located down in the crankcase with valves operated with solid or hydraulic lifters.

Oil cooler: A small radiator through which the engine oil flows to help cool the engine by taking heat out of the motor oil.

O-ring chain: A final drive chain design that includes O-rings to seal lubricant within the chain rollers and pins.

Over-square: A term that refers to the ratio of the bore to stroke when the bore diameter is greater than the length of the piston stroke. An engine is “undersquare” when the bore diameter is less than the length of the piston stroke.

Panhead: Nickname for the Harley-Davidson V-twin engine design in use from 1948 to 1966 when the design gave way to the Shovelhead. Panhead comes from the appearance of the rocker covers resemblance to a cooking pan.

Pannier: Typically refers to saddlebags or storage boxes on either side of a fairing on a motorcycle.

Pillion: Passenger seat, or the person on it. Also the “buddy seat.”

Pilot jet: The jet in a carburetor that regulates fuel flow at low speed.

Plain bearing: A bearing with no rollers or needles but with load-bearing surfaces consisting simply of flat, smooth surfaces that rely on a film of lubricant between the surfaces to bear the load.

Top 120 Non-Vulgar Motorcycle Terms | Technical & Slang
Contact breaker points: Archaic ignition system, but effective when properly set.

Points: Contact breaker points; a mechanical device in early ignition systems to trigger the spark at spark plugs by opening and closing the ignition circuit. Or, in deer hunting parlance, the number of antlers in a buck’s rack.

Polarity: The designation of charge in a battery or circuit; positive (+) or negative (-).

Power band: The upper and lower range of engine speed (RPM) where the greatest amount of usable power is produced by the engine.

Pre-unit: A term most often applied to Triumph 650 cc bikes built before the transmission and engine were combined into a single “unit” in 1963. Certain BSA models became “unit” construction in 1962.

Primary drive: The system that transfers engine power from the crankshaft to the transmission; it usually will be belt or duplex or triplex chain.

Pudding bucket: Early style of half-helmet.

Rake: The angle of the front fork from vertical in degrees. See also: trail.

Rectifier: A device in an electrical system that converts alternating current (AC) to direct current (DC).

Red line: The maximum number of revolutions per minute (RPM) the engine is designed to be able to reach safely, which is then expressed as a red line or zone of red color on the face of the tachometer. (See also: rev limiter).

Regulator: A device in an electrical system that maintains voltage.

Riser: A device used to increase the height of the mounting point of the handle bar above the top triple clamp.

RPM: Revolutions per minute, or an expression of engine speed.

Rev limiter: This is a system that steps in to prevent engine damage from exceeding the safe limit on engine speed when the rider chooses to ignore the red line. It acts to keep engine RPM at or below the red line by cutting ignition to one or more cylinders when the red line is exceeded, thereby limiting the revolutions per minute. Older bikes not so equipped when taken beyond the red line may fall into an alternate engine category: “shrapnel.”

Rocker arm: A lever that transfers force from a pushrod or camshaft to open and close intake and exhaust valves. The “rocker box” is the casing atop the engine that contains the rockers.

Roller bearing: A bearing where the rollers are cylindrical in shape. Tapered roller bearings have one end of the cylindrical shape smaller than the other.

Shock absorber: A rear suspension unit typically consisting of a coil spring with a hydraulic damping system. Some systems have mechanisms to increase spring tension (preload), damping action and some may be air-adjustable. “Shock” is the slang form, but may also refer to the potential buyer’s reaction to the price of some bikes.

Shovelhead Sporty:  H-D Shovelhead
Shovelhead Sporty: H-D Shovelhead, in Sportster form.

Shovelhead: Nickname for the cylinder head configuration (image) used on Harley-Davidson V-twins from 1966 to late 1983 when the Evolution or “Blockhead” motor was phased in. So named because the rocker covers resembled a shovel—if only at a glance.

Slider: The lower, moving portion of telescopic forks. In older fork designs, the slider typically slides up over the top part of the fork leg; in “inverted fork” designs, the larger diameter is on top and the smaller diameter portion of the fork leg slides up into it. May also refer to blocks of plastic Valentino Rossi wannabes have velcroed to the knees of their leathers.

Snell Memorial Foundation: An organization devoted to safety that tests helmets against a set of objective standards for performance. Snell certification is voluntary on the part of the helmet manufacturer. For more on Snell, see: www.smf.org/

Sprung hub: An older rear suspension design with the spring located in the rear wheel hub.

Steering head: The part of a motorcycle frame where the forks mount to the frame at their pivot point.

Stroke: The distance the piston travels inside the cylinder of the engine. (See also: Bore).

Sump: The reservoir for engine oil. In engines where the bottom of the crankcase forms the sump, the engine is said to be a “wet sump” design; where the oil is carried in a separate tank, the design is said to be a “dry sump.”

Swingarm: The rear suspension component that carries the rear wheel, pivots at the frame and moves with the shock absorber. It may be a double-side or single-side unit.

Tachometer: The instrument that indicates engine speed in revolutions per minute, making it more convenient to know when you might grenade your engine.

Tank-slapper: A steering anomaly that usually occurs at high speed with the forks oscillating rapidly lock to lock, often resulting in loss of control.

Setting tappet clearance:  Setting tappet clearance on an old Honda.
Setting tappet clearance: Setting tappet clearance on an old Honda.

Tappet: Also referred to as a cam follower, it rolls along the cam face, converting cam lift to linear motion to open and close intake and exhaust valves. Setting the clearances correctly (image) is the key to quiet valve train operation.

TDC: Top dead center, or the uppermost extent of the distance traveled by the piston.

Timing: Sequencing of valve opening and closing and synchronization of delivery of the ignition voltage to the spark plugs. When either is off, all bets are off.

Torque: The rotational force produced by the engine, often expressed in foot-pounds; multiplied by RPM, it defines the horsepower output.

Trail: The horizontal distance from the front wheel centerline and point the steering head axis projected to the ground.

Triple clamp: The pair of y-shaped brackets into which the fork legs are mounted with the steering head pivot point in the middle.

Triplex chain: A roller chain design with three rows of rollers used for primary drive.

Twin cam or twin camshaft: An engine with two camshafts for a bank of cylinders. Twin cam or “TC” may also refer to a V-twin engine design introduced in 1999 by Harley-Davidson. Twin cam “B” or counter-balanced engines followed in 2000.

Twin leading shoe brake: A drum brake with two shoes that act simultaneously.

Two stroke: An engine design where intake, compression, ignition (power) and exhaust all occur on every revolution of the engine.

Under-square: Engine piston stroke dimension is longer than the diameter of the cylinder bore.

Unit construction: Engine and transmission are a single unit.

Viscosity: The rating of a fluid’s ability to flow or thickness—as for motor oil.

Water Buffalo Suzuki
Suzuki Water Buffalo

Water Buffalo: Affectionate nickname for the Suzuki GT750 liquid-cooled two-stroke three cylinder.

Wheelbase: The horizontal distance between the axle of the front and rear wheels.

Widowmaker: Nickname for the Kawasaki Mach IV—and applied to the Mach III by some.

Wire wheel: The wheel design where the outer rim and hub are joined by metal spokes; also simply referred to as a spoked wheel. This design usually requires tube-type tires.

Wrist pin: the rod or tube running through a piston that also runs through the top of the connecting rod. Gudgeon pin in Brit bike parlance.

Zed: Slang term for the Kawasaki Z1. For more –  Z1 literature.

Zener diode: A voltage regulator that drains off excess voltage to allow it to be dissipated from an air-cooled finned heat sink.