Cafe Brawler: Bimota’s KB4 RC

Bimota takes the gloves (and the fairing) off.

Think some other sportbikes look angular? You haven’t seen anything until you’ve seen the new Bimota KB4 RC.Bimota

When Bimota revealed its KB4 at EICMA 2021, enthusiasts were surprised by its relatively soft look and mild performance, both of which were in direct contrast to Bimota’s aggressive, immensely powerful 2020 Tesi H2. That bike represented Bimota’s return to the motorcycling stage after becoming a member of the Kawasaki Group.

The KB4 is powered by the highly flexible 142 hp edition of the Kawasaki 1,043cc four (77 x 56mm bore and stroke, 11.8:1 compression) and is intended to be a real sportbike in the best Bimota tradition, a combination of a refined chassis and a smooth yet strong engine. The styling is relatively retro, with a rounded top fairing underscoring the bike’s purpose. Bimota also announced a naked edition that was not on display at EICMA 2021.

Notice the lack of radiator in this image. Bimota takes the base Kawasaki and gives it a total makeover. Also note the twin air ducts flanking the chassis; guess where they lead?Bimota

Now we see it, and the result is quite striking. The bike’s key technical specifications are unchanged, yet its exclusive features are more clearly visible and appreciated. This much is undeniably clear: The KB4 RC is definitely a pure cafe racer, and it looks immensely tougher than the earlier dressed edition.

The front view is dominated by a pair of air intakes reminiscent of the McDonnell Douglas F-4 Phantom’s. These route cooling air to the engine’s radiator, located diagonally between the seat and the rear wheel. The ducts are specifically shaped to ensure a correct, comfortable seating position for the rider while keeping them insulated from radiator heat. An electric fan located behind the radiator draws in cooling air at low speeds; at higher speeds the ducts’ intakes scoop in plenty of ram air. Once it has cooled the radiator, the hot air exits through a duct at the end of the tail.

The answer to the “where’s the radiator?” question—it’s under the seat. And not a winglet in sight.Bimota

The KB4 RC has a compact 54.7-inch wheelbase. Steering rake is a sport-inspired and relatively steep 24 degrees with 3.97 inches of trail. Both front and rear suspension components are semi-active electronically controlled Marzocchi units, a 50mm male-slider fork and a monoshock rear. The braking system is all Brembo: twin 320mm front discs with Stylema four-piston calipers and a single 220mm rear disc with a two-piston caliper, all with ABS. The forged-aluminum wheels are mounted with 170/70-17 (front) and 190/50-17 (rear) radials. Seat height is an easily accessible 31.9 inches, and dry weight is a claimed moderate 412 pounds.