Simulate your riding position on any motorcycle.

Battery Information

How to do Stoppies

How to do wheelies

Motorcycle Chain Maintenance

What kind of biker are you?

Motorcycle Jokes

Tire Pressure

Water Injection System


Acronyms, Terms & Definitions

ABS Anti-lock Braking System
APRC Aprilia Performance Ride Control
ASC Automatic Stability Control
Auto Blipper  

Bore and Stroke

Relationship between the diameter of a cylinder and the length the piston travels

Brake Calipers Fixed and Floating Calipers
Camshaft Single or Double Overhead Camshaft (SOHC or DOHC), Pushrod
Carburetor Blends air and fuel for an internal combustion engine.
Catalytic Converter Converts harmful emissions to harmless compounds
Cellasto Microcellular polyurethane elastomers that enhance driving comfort
Clutch Multi-plate, wet, dry
Compression Ratio Ratio of the volume of a combustion chamber from its largest capacity to its smallest capacity
Counter Steering "Steer left to turn right"
Crankshaft Transforms the energy from the pistons (lineary) into a rotary motion
CVT Continuous Variable Transmission
CDI Capacitor discharge ignition
Desmodromic Valve A reciprocating engine valve that is positively closed by a cam and leverage system
Disc Brakes Difference between fixed and floating disc brakes
DOHC Double Overhead Camshaft
Drum brakes Single or twin leading shoe
DSS Ducati Skyhook System
ECU Electronic Control Unit
EFI Electronic Fuel Injection
ESA Electronic Suspension Adjustment
EXUP Exhaust Ultimate Power Valve
Floating Sprocket To help keep the sprocket properly aligned
Four Stroke Engine Most popular modern motorcycle engines
Gear Ratios Explaining the relationship between various components and how it impacts on power delivery
GVWR Gross Vehicle Weight Ratio
High Side Losing control as a result of extraordinary power added to the rear wheel
Hub-center steering An alternative front-end steering/suspension system
Knucklehead Engine Harley-Davidson motorcycle engine
Leading shoe Drum brake - single or twin leading shoe
Multi-plate clutch The most common motorcycle clutch
Paralever Eliminating "jacking" in a shaft driven bike
PCM Powertrain Control Module
Power and Torque Both are needed to get your bike moving.  But what is it?
Pre-unit just & Unit construction is Pre-unit just means that the engine crankcase and gearbox are two separate units bolted into the same frame, whereas unit construction means the gearbox and crankcase share the same casing.

Early motorcycles were largely pre-unit as it was simpler to cast gearbox and engine casings separately at the foundry, and manufacturers could buy in engines and/or gearboxes and pair them up without any major issues.

Unit construction is used for essentially all modern motorcycles, it results in a lower total weight, much better rigidity, fewer places to leak oil, and improved simplicity.

Pushrod Camshaft located inside the engine rather than in the head and driven by pushrods
Quick shifter  
Radial Brakes Radial or Axial Brake Calipers
Rake The angle between the neck a bike and a vertical line
Ram Air Increasing engine power through the use of airflow
Reed Valve A valve opening under vacuum to allow fuel/air mixture to enter the crank of a 2-stroke
RFVC The RFVC indication on the head off the engine means: Radial Four Valve Combustion. RVFC or Radial Four Valve Combustion was a proprietary valve arrangement created by Honda to make a four valve head flow more like a hemi head. The splayed valves arrangement allows quicker flame propagation across the combustion chamber, allowing the engine to produce more power at a given RPM.
Ride by Wire The use of electrical or electro-mechanical systems for performing vehicle functions traditionally achieved by mechanical linkages/acruatiors
Seamless Gearbox Also referred to as seamless shifting, seamless transmission or Zeroshift transmission
Shock Absorbers Single tube, double tube, front, rear
Slipper clutch  
SOHC Single Overhead Camshaft
Steering Damper Inhibits undesirable movement of the steering mechanism.
Supercharging How these forced air induction systems work and why they are the way of the future.
Sump Wet and dry sump
Suspension adjustment Also covering both front and rear suspension rebound and compression settings
Swingarm The main component of the rear suspension to hold the rear axle firmly, pivot vertically, allowing the suspension to do its work.
Tank Slapper An unwanted, quick and scary oscillation of the front wheel
Telelever A BMW patented front suspension system
Torque Refers to force - read power and torque
Traction Control Designed to prevent loss of traction of road driven wheels
Trail The distance between tyre surface contact and a vertical line from the axis to the surface
Triple Tree Central to the steering mechanism of a bike
Turbocharger Boosting an engine without significantly increasing weight
Two Stroke Engine Mainly used on smaller bikes, such as 50 cc.  Reducing in popularity due to pollution
VTEC Variable Valve Timing and Lift Electronic Control
Weight Dry vs Wet/Curb Dry weight is what the bike weighs without fluids - without gas, oil, coolant, final drive fluid, or sometimes even the brake fluid and battery.  Motorcycles are typically shipped dry for ease of handling and safety.

Wet weight/curb weight  is a term used to refer to the weight of a motorcycle when it has been loaded with all the fluids it needs to operate, along with the battery.  Generally only a half tank of gas, ready to ride.

But these terms are not standardized across the industry.

Wheels A discussion on spoke and alloy wheels
YPVS Yamaha Power Valve System


Tech Videos



1  2  |  3  |  4  |  5  |  Next