MXA TEAM TESTED: R&D GENIUS THROTTLE BODY

WHAT IS IT? A replacement throttle body for most modern motocross bikes.

WHAT’S IT COST? $1499.00 (throttle body kit with Vortex black box).

CONTACT? www.r1dean.com or (562) 864-8218.

WHAT STANDS OUT? Here’s a list of things that stand out with the R&D Genius throttle body.

(1) The idea. R&D’s stroke of genius was to invent a rotating gate design. Instead of a flat slide or a butterfly valve, R&D designed an elliptical barrel that rotates inside the throttle body’s venturi. The elliptical barrel rotates completely out of the way at full throttle, and because of its smooth shape, the air flows over it with less disturbance.

(2) Bad butterfly. The common throttle body uses a butterfly valve to open and close the venturi of the throttle body’s bore. Butterfly valves are cheap, but they aren’t aerodynamic. No matter whether the throttle is open or closed, the butterfly always creates turbulence that lessens fuel velocity.

(3) Maximum velocity. When you open R&D’s elliptical barrel, it rotates completely out of the way. And by full throttle, it not only disappears but becomes the smooth bottom surface of the throttle’s bore.

(4) Delay. MXA first tested R&D’s Genius throttle body two years ago, but only a handful of people ever got to use it because Dean couldn’t find a machine shop that could mass-produce the complex throttle body. Now, R&D has solved its production problems and is shippimg.

Throttle closed.

Throttle half open.

Throttle wide open.

(5) Flow. First and foremost, the Genius throttle body is designed to improve low-end power and partially open throttle response and pickup through the midrange. The smooth-flowing characteristics of the Genius design have the biggest effect when engine vacuum is low and fuel misting is compromised. Once the throttle body is wide open, the Genius barrel is completely out of sight.

(6) Performance. Every MXA test rider liked the throttle response of the Genius on both our CRF450 and YZ450F. It smoothed out any irregularities, boosted horsepower and made the bikes easier to ride. It was a clear-cut improvement in the brain-to-throttle equation, which is probably why the Geico Honda team used it and Doug Dubach had it on his bike when he won the World Vet Championship. In fact, several factory road racing teams are using rotating barrel throttle bodies on their race bikes—including the Honda of 250cc MotoGP Champion Alex Marquez.

WHAT’S THE SQUAWK? This isn’t a cheap mod. It involves a complex, CNC-machined piece and a new electronic ECU (supplied). It is a serious racing product that improves throttle response and power, but since it isn’t visible to the naked eye, it’s not for the status conscious guy. It is designed to take a hopped-up engine to the nth degree