Fuel is then fed through tiny passages called "jets," which control how much gas flows into the combustion chamber-most carbs feature two jets, with the main jet controlling the fuel mixture at mid to high RPMs and the pilot jet controlling from idle to the middle of the rev range. While carburetors are elementary in function, tuning them properly is a long and arduous job that only veteran mechanics have perfected.
"Once you have a two-stroke 95 percent of the way there, that last 5 percent is really what's difficult to get down," says Joe Adragna, an amateur motocross racer who rode two-strokes throughout his childhood.
While a carburetor allows you to adjust the air-fuel ratio, it's more of a set-it-and-forget-it type of device. Fuel injection (or throttle-body injection in the case of KTM's two-strokes) is continuously variable. The process is now controlled automatically via an onboard engine management system that ensures a near-perfect air-fuel ratio all of the time. With more usable power and higher fuel efficiency, these engines feel much closer to a four-stroke when twisting the throttle open.
"We saw the benefits on the four-stroke side when we made the switch from carb to EFI more than 14 years ago," says Bretterebner. "Some of these benefits apply even more on a two-stroke engine, which is more sensitive in terms of air-fuel ratio."
Esta historia es de la edición March - April 2023 de Popular Mechanics US.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor ? Conectar
Esta historia es de la edición March - April 2023 de Popular Mechanics US.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor? Conectar
ONE OF THE 'GREATEST THREATS' TO THE PACIFIC NORTHWEST ISN'T WHAT YOU THINK.
EXPERTS ARE PREPARING THE REGION AGAINST THE THREAT OF DANGEROUS VOLCANIC MUDFLOWS, KNOWN AS LAHARS, WHICH COULD INUNDATE THE COMMUNITIES SURROUNDING MT. RAINIER IN AS LITTLE AS 30 MINUTES.
THE WORLD'S TOUGHEST ROW
They rowed 3,000 miles across the Atlantic, battling unpredictable weather, chaotic seas, and finicky equipment. But what they discovered gave them profound new insights into the power of the ocean.
HOW TO DIY OFF-GRID SOLAR
SPEND THE TIME UP FRONT AND PLAN IT CAREFULLY TO AVOID DISAPPOINTMENT
Are We on the Verge of an ARMS RACE in SPACE?
RUMORS OF A RUSSIAN SPACE NUKE, ALONG WITH OTHER SATELLITE-TARGETING WEAPONS, HAVE MADE GEOPOLITICAL TENSIONS EXTEND INTO ORBIT.
Fresh Fingerprints on an Ancient Statue
A CLAY FIGURINE HAS SPENT MILLENNIA incomplete, waiting at the bottom of a lake for its long-dead craftsman to finish the Iron Age-era statuette.
Quantum Entanglement in Our Brains
IT HAS LONG BEEN ARGUED THAT THE human brain is similar to a computer. But in reality, that's selling the brain pretty short.
The Tools of Copernicus
WAY BACK IN 1508, WITH ONLY LIMited tools at his disposal, Nicolaus Copernicus developed a celestial model of a heliocentric planetary system, which he described in hist landmark work De revolutionibus orbium coelestium. It was a complete overhaul of our conception of the universe-one that, unfortunately, earned him the ire of the Catholic church for decades after his death-and forever changed the way we look at the stars.
Building a Sixth-Generation Bomber Raptor
THE GLOBAL COMBAT AIR Programme (GCAP)-a project by the U.K., Italy, and Japan to develop a sixth-generation stealth fighter-has been busy at the drawing board reshaping its vision of the future of air warfare. And judging by the new concept model unveiled at this year's Farnborough air show, that future has big triangular wings.
The Electroweak Force of the Early Universe
TODAY, THE UNIVERSE AS WE KNOW IT IS governed by four fundamental forces: the strong nuclear force, the weak nuclear force, electromagnetism, and gravity.
This Ancient Fossil With a Brain and Guts
WE KNOW WHAT FOSSILS LOOK like. For example, typical dinosaur fossils are bones turned to stone and preserved from the passage of time, located, if we're particularly lucky, in large collections that can be reassembled to represent the beast they used to prop up in their entirety.