WHAT IS IT?
A complete float bowl, accelerator pump and fuel supply
system for the Keihin FCR carburetor.
WHAT’S IT DO?
During the two-stroke era (1967-2004), the nagging carb
problems were lean or rich mixtures. Not anymore! Now,
on four-stroke engines, bogging, coughing and popping are
the bugaboos.The solutions to these problems, most
commonly found on the CRF250 and CRF150, range from
aftermarket accelerator pump covers to radical jetting
changes to accelerator pump linkage mods. R&D Racing,
famous for their long association with the Suzuki amateur
program, has a totally new solution—which doesn’t address
just one issue in the bogging equation, but every aspect. It’s
their totally innovative, R&D Power Bowl.
WHAT STANDS OUT?
(1) FUEL SUPPLY
In jumps and whoops, the fuel in the main jet fuel chamber (a little plastic cavity designed to keep a ready supply of fuel
available for the main jet) can cavitate.Why? The stock Keihin’s plastic chamber has excessive clearance under it. The gap allows the fuel in the main jet chamber to get mixed with air bubbles which results in a lean condition. The Power Bowl has a “zero tolerance” mainjet fuel chamber. It is totally sealed to keep the fuel from sloshing away from the main jet.
(2) ACCELERATOR PUMP
The R&D Power Bowl is designed with two separate fuel ports.
The first orifice is isolated at the highest point of the accelerator pump to vent trapped air out through the leak jet. The second orifice is located low in the fuel sump to insure a supply of air-free fuel to the accelerator pump circuit.
(3) LEAK JET
The Power Bowl comes with an easy-to-use, externally adjustable leak jet. Additionally, the ball check valve that controls fuel flow has been repositioned to the bottom of the pump to stop it from bouncing open and closed during hard landings (and a nylon check ball is used instead of a steel one to lessen the weight against the ball check spring).
(4) PERFORMANCE
The MXA wrecking crew tested the R&D Power Bowl over a fourweek test cycle on a CRF150, RM-Z250 and CRF250. We were impressed. On the CRF150, which has a tendency to shoot ducks at full throttle, the popping disappeared and the power improved considerably (so much so that we went up on both the main and the pilot jets).On the RM-Z250, the transition from low-to-mid was enhanced,while the overrev was lengthened. On the CRF250, it eliminated the irritating bog, allowed us to go richer on the jetting and improved overall power. Across the board, throttle response was improved and midrange power increased. |
