Like dogs, outboards age at an accelerated rate, and there were few older than the loyal-but-outdated Honda BF90, a nine-year-old design still hanging around dealer showrooms last summer. This year, Honda (www.honda-marine.com) will have a new pup in its place, an-all new BF90 ($9,585) that is an upgrade in every respect.
Honda starts with a new 1496cc powerhead, a four-cylinder, single overhead-cam design with about 100cc less displacement than the previous BF90. Dry weight is down by 14 pounds, from 373 pounds to 359 pounds for the 20-inch model. Only the 320-pound, three-cylinder Evinrude E-TEC 90 (www.brp.com) two-stroke weighs less among six competitors in the 90-hp class.
This engine has all the techno bells and whistles Honda has installed on its more-recent outboard designs, including electronic fuel injection (the old BF90 was the last outboard in this class still using carburetors), VTEC variable intake valve timing, and a lean-burn system that improves fuel economy. It also features a patented ignition timing system called BLAST (Boosted Low Speed Torque) that is supposed to improve initial acceleration.
BLAST is designed to take advantage of a rich fuel mixture condition that occurs whenever you dump the throttle to get the boat on plane. When the throttle is advanced quickly, the fuel injection system instantly responds with a big squirt of gas. However, it takes a few micro-seconds longer for the air flowing into the engine to catch up. The result is a momentary rich mixture. The BLAST feature compensates by advancing ignition timing right to the limit of detonation, which is determined in part by a knock sensor on the motor. The result, according to Honda, is maximized power and acceleration for about the first 150 feet of hole-shot. You'll feel it as especially crisp throttle response.
This motor is also fitted with an oxygen sensor in the exhaust, a key component in the lean-burn control system that constantly fine-tunes fuel delivery rates to let the motor run as lean as 18:1 (air: fuel) when possible, mostly at steady speeds between 2000 and 4500 rpm. Honda says this results in a fuel savings of up to 30 percent at mid-range speeds. VTEC gives this motor two intake cam profiles, short duration for smoother operation at lower speeds, and long-duration for more power, engaged by the computer at engine speeds above 5300 rpm. A Honda insider tells me VTEC is worth 12 to 15 additional horsepower at wide-open throttle — this "90-hp" model actually makes 97 hp at 6000 rpm, seven more horsepower than the old BF90.
This technology all works so smoothly that you are not likely to notice it while underway. More obvious is a new gearcase design, with a more hydrodynamic leading edge and a half-inch longer bullet, streamlining that Honda says produces a top-speed gain of 1 mph over the previous gearcase. A new splash plate above the gearcase is there specifically to keep water from spouting up the front of the motor when it's installed on a pontoon boat. A new patented alternator design places lightweight neodymium magnets under the flywheel and produces 44 total amps (35 amps to the battery), compared to just 14 amps for the previous BF90.
I like the new hoop-type cowl latches, which are not as attractive as internal latches but are easy to use and won't corrode or get gummed up with saltwater. New electronic instruments, which include a fuel-flow meter, are available for this motor, and the fuel filter features a water-in-fuel sensor.
How's it run? It's a Honda, so it's smooth, quiet and sophisticated. Pre-production examples I ran did not have final computer programs, so I can't vouch for the fuel economy claims, but the hole-shot feels strong so maybe BLAST makes a difference. The BF90 gives up a lot of displacement to other 90s you might consider. The Suzuki DF90 (www.suzukimarine.com), for example, has a 1950cc powerhead that is also rated for 115 hp, but that motor weighs more than 400 pounds. Designed from top to bottom to make the most power possible from every drop of fuel, the new Honda BF90 is a new dog that knows some new tricks.
The new Honda BF75 ($8,995) features the same powerhead as the BF90 and most of its features, but does not have VTEC.
Both the BF90 and BF75 are available with a new center-mount tiller control that incorporates the shift lever, power trim button, an LCD information screen and key switch. It can be adjusted to one of three different angles to best comfort.
Honda will include a free warranty upgrade from three to five years on all new BF90/BF75 motors purchased before March 31, 2007.
Editor's Note: Charles Plueddeman is the editor at large for Boating, the nation's largest recreational boating magazine.