Displacement – Triumph Rocket III 2294cc In-Line Triple Engine
Dammits – Those devices on the back of your pins that you will almost always drop. Can be used synonymously with Jesus-clips
Dampen – The act of eliminating, or device used to eliminate (damp), unwanted oscillations (vibrations) and unwanted energy.
Damper – Device for controlling unwanted movement or absorbing unwanted energy. Weighted bar ends, bar snake, buckshot, gel handgrips are items used to dampen handlebars.
Day-Long – A custom motorcycle seat made by Bill Russell.
DBM – Double-breasted Mattress Thrasher – when you’re out ‘bird’ watching.
DC – Direct Current.
Death Grip -Usually how a first time rider grabs the handle bars.
Decreasing Radius Corner – A turn where the arc gets sharper as you progress through the curve.
Deflector Piston – Piston designed for two stroke engines to channel fresh fuel up to the head forcing burnt fuel out the exhaust posts.
Delta-V – A change in velocity, acceleration or direction.
Denier – a unit of measurement used to describe the strength of a material like nylon. Simply – the bigger the number the bigger the thread.
Desmodronic – Ducati designed valve opening and closing system that does not rely on springs. Design offers better high RPM valve control. Desmodromic valves are closed by a cam and rocker arm rather than a valve spring. Advantages include less friction, higher valve acceleration and deceleration without the risk of valve float and higher engine speeds for a given valve size. Disadvantages include greater complexity of the valve train and the need for more frequent adjustment intervals. All Ducati motorcycles still use desmodromic valves today.
Detailing – In-depth cleaning, polishing, waxing and other maintenance to make a motorcycle look great.
Detonation – See Pre-Ignition.
Diamond Frame – Tubular frame design derived from the bicycle layout. The engine cases often form part of the structure. In profile it resembles a diamond shape.
Dicing – 1. Taking the risk of racing one or more riders, usually on public roads. 2. Riding a motorcycle in dense traffic.
Dieseling – Ignition in a gasoline engine of the fuel vapor by means other than spark plug. Also called per-ignition or run-on.
DILLIGAF – Do I Look Like I Give A F_ _ K
Ding – A nick or scratch in the paint.
Dip stick – (1) The long slender piece of plastic or metal that goes into the oil reservoir of an engine or sump and is used to manually check the oil level. (2) An alternate derrogatory name for a person who is acting or has acted like an idiot.
Dirt Bike – Bikes intended for off-road use that are not legal to ride on public roads. Sometiemes the term “pure dirt” is used to distinguish a dirtbike from a dual sport motorcycle.
Discs – These are the metal rotors the caliper presses the pads against to brake.
Disc Brake – Brake that utilizes friction pads held in a caliper on either side of a rotation disc.
Displacement – 1. The size of an engine, in cubic centimeters (cc) or cubic inches (ci). 2. The volume through which the piston travels during a single stroke of an engine. This term is sometimes also used for the total volume displaced by all engine pistons. The displacement is measured in cubic centimeters (ccm).
Distributor – An electrical circuit breaker often consisting of points, timing advance device, condenser and cam used to direct high tension current to spark plugs at the proper timing. Often replace with electronic ignition.
Dive – 1. Tendency of the front suspension to compress during hard braking. 2. To quickly change direction such as suddenly leaning the bike into a tight turn.
DOHC – Dual OverHead Cam. Two camshafts found in the head or top of the engine that open and close the valves. Two cams allow more precise control than one.
DOHV – Double OverHead Valves.
Dope – Highly combustible alcohol/methanol-based fuel mixture.
Doubles / Triples – Doubles and triples are large multiple jumps that allow riders to fly through the air rather than traversing each jump one at a time. Triple jumps are the signature obstacle of Supercross, requiring cool nerves and precise throttle control.
Doughnut – Rider who performs a burn out and carefully moves the motorcycle to encompass a 360-degree circle thus leaving a circular mark of rubber on the road surface.
Donor Cycle – Firefighter Term for Sportbikes because their drivers tend to kill themselves.
Do-Rag – Cloth coverings that are used to cover the rider’s hair and forehead in an effort to keep sweat from dripping into the eyes and to avoid ‘helmet hair. Also can be used as a fasion statement.
Dos Equis – Honda CBR1100XX Blackbird
DOT – Department of Transportation. Each country has its own separate DOT. It’s a government agency that regulates all phases of transportation, including all types of vehicles, as well as roads and highways. A DOT rating on a motorcycle helmet indicates that it’s passed DOT testing and a DOT sticker can be found inside the helmet.
Dual plugging – Adding a second spark plug to the head of a motorcycle engine. Increases fuel efficiency and horsepower.
Double Cradle Frame – A bike frame with two steel tubes circling the engine from the front and “cradling” it.
DQ’ed – Disqualified (as in a race).
Drag – The resistance of the air to forward motion. A flat disc moving broadside along its axis has a nominal rating of 1.00
Drag Bars – A straight styled handlebar that does not sweep up from the risers. Low, flat, straight handlebars.
Drag Pipes – 1. These were short exhaust pipes that ran low along the frame. 2. Straight exhaust pipes with no baffles.
Dresser – A motorcycle set up for long distance touring.
Drum Brake – Brake design with brake shoes forced out against a rotation drum.
Dry race – A race in which climatic conditions affecting the track surface are considered to be dry, opposed to wet.
Dry Sump – Lubrication system in four-stoke engines in which the oil is carried in a separate container. Oil drains into the sump and is pumped into the separate container, keeping the sump “dry.”
DSA – Driving Standards Agency. The UK government body which, among other things, controls the content of the British bike test.
DTGO – Dyin’ To Get Off – Refers to either the rookie female passenger or the seasoned one, depending on how you look at it.
Dual plugging – Adding a second spark plug to the head of a motorcycle engine.
Dual Purpose Motorcycle/Bike – Designed for most types of terrain, the name describes a bike that has off-road capabilities with street legal accessories. BMW F650, Honda XR650L, Suzuki V-strom, Kawasaki KLR650, Yamaha XT225, Buell Ulysses are examples of a dual purpose bike.
Dual Sport – 1. A dual purpose motorcycle, made for both on and off the road travel. See Dual Purpose Bike. 2. Street legal motorcycles with varying degrees of off-road capabilities. Also called Dual Purpose Motorcycle/Bike.
Duals – 2 separate Exhaust pipes, ie one each for front and rear cylinder.
Duc(s) – A Ducati motorcycle.
Duck – Slang for a Ducati motorcycle.
Duck Walking – When you sitting on the bike and pushing it with your legs and feet. Paddling the bike along to make it move.
Duke – A Ducati motorcycle or a KTM Super-Duke.
Dump the cltuch (Drop the clutch) – A rider quickly releases the clutch while the revs are high.
Dumping the Bike/Dumped the Bike – A zero speed spill. A bike is dumped when the rider applies brakes while in a very slow turn, or is trying to get his bike up onto (or off of) its center-stand, or is walking the bike and it gets away from him, or forgets to put the side-stand down and tries to get off the bike, or any of dozens of other ‘dumb’ things that lead to losing control of the bike and its laying over onto the ground.
DuPont Coolmax® – DuPont Coolmax® consist of hollow fibres which transport humidity to the outside very quickly by means of capillary action making the material dry 50% faster than cotton.
Dynafil – A highly tear-resistant polyamide yarn that is even more robust than Cordura® 500/700 and is even more resistant to high temperatures.
Dynamite – Slang for instantly applying a system to full force. (eg. I dynamited by brakes.)
Dynamo – Electric generator that produces alternating current.
Dynatec – Fabric made of Dynafil. Highly tear-resistant and extremely robust. Its melting point is 290 °C.
Dynamometer – Often called a “dyno”, it is a device for measuring force, torque or power.