The slow air jet, not to be confused with the slow fuel jet (pilot jet), works in tandem with the carburetor pilot jet to control the volume of air delivered to the pilot circuit. It is located on the intake side of most carburetors and may be adjustable or of a fixed size.
Supersport bikes are advanced-level, high-performance oriented motorcycles designed for street use. Cost of ownership is typically slightly higher than that of less exotic sportbike motorcycles.
Sportbikes are entry-level, performance oriented motorcycles designed for street use. They are typically economical to own and operate.
The Society of Automotive Engineers (SAE) International has produced a simple, consistent and economical sound test standard that can be used to determine whether a streetbike (on-highway motorcycle) exhaust system emits excessive sound, the American Motorcyclist Association (AMA) reports.
The J2825 “Measurement of Exhaust Sound Pressure Levels of Stationary On-Highway Motorcycles,” issued by the SAE in May, establishes instrumentation, test site, test conditions, procedures, measurements and sound level limits. According to the SAE, the J2825 standard is based on a comprehensive study of a wide variety of on-highway motorcycles.
“The motorcycling community and law enforcement have long sought a practical field test for measuring street motorcycle exhaust sound,” said Ed Moreland, AMA vice president for government relations. “Thanks to the hard work of the Motorcycle Industry Council, and the SAE engineers involved in the project, for the first time a simple field test is now available.
“The AMA maintains that few factors contribute more to misunderstanding and prejudice against street riders than excessively noisy motorcycles,” Moreland continued. “With the new SAE J2825 standard, street motorcyclists can now determine how quiet, or loud, their bikes really are.”
Moreland added that the new standard follows a template established years ago with the SAE J1287 off-highway motorcycle sound test, a standard recommended by the AMA wherever off-highway motorcycles are operated.
The SAE J2825 on-highway motorcycle sound test procedure is similar to the one used for the SAE J1287 off-highway motorcycle test. The streetbike measurement requires holding a calibrated sound meter at a 45-degree angle 20 inches from the exhaust pipe of a running engine. The procedure spells out how to do the test with the bike at idle, at a predetermined engine speed (“Set RPM Test”), or by slowly increasing the engine speed of the bike, known as the “Swept RPM Test.”
The SAE J2825 standard, prepared by the SAE Motorcycle Technical Steering Committee, recommends a decibel limit of 92 dBA at idle for all machines or — using the Set RPM or Swept RPM Test — 100 dBA for three- or four-cylinder machines, and 96 dBA for bikes with fewer than three or more than four cylinders.
The creation of a new street motorcycle sound measurement procedure was a top recommendation of the 2003 National Summit on Motorcycle Sound, expressed by its Motorcycle Sound Working Group. The AMA organized the National Summit on Motorcycle Sound to pull together riders and user organizations, representatives of the motorcycle manufacturers, the aftermarket industry, racing promoters, government agencies, and others to develop proposals regarding the increasingly controversial issue of excessive motorcycle sound.
“The J2825 test allows jurisdictions around the nation, struggling with complaints about excessive motorcycle sound, to set reasonable limits in accordance with the SAE standard,” said Moreland. “While the AMA supports the establishment of the SAE J2825 standard in America’s cities, towns and communities, we will continue to fight efforts that single out motorcycles while still permitting excessive sound from other sources, such as loud cars and trucks, booming car stereos, poorly maintained generators, whining leaf blowers, and the like.”
The SAE J2825 standard can be downloaded on the SAE website for a fee at http://www.sae.org/technical/standards/J2825_200905.
A screw or bolt extractor is a device used to remove broken bolts, screws and fasteners. They are available from most motorcycle and automotive stores.
An electrical failure in which the current flow bypasses (takes a shortcut before) the resistance of the load and goes directly to ground. Short circuits can result in blown fuses, melted wires and damaged components.
Refers to the relative weight of a fluid as compared to an equal volume of distilled water. It is common to check the specific gravity of engine coolant and battery electrolyte to determine if they are within specification using a tool called a hydrometer. There’s even a type of hydrometer that tells you when your homemade beer is ready to be bottled!
When the piston in a motorcycle engine moves from TDC (Top Dead Center) to BDC (Bottom Dead Center) or from BDC to TDC – the distance traveled is referred to as the stroke. The stroke takes one half of a revolution of the crankshaft.
A device which uses mechanical or hydraulic friction to reduce motorcycle steering oscillation at high speeds.