Part of Throttle Times’ live coverage of EICMA 2026.

Bimota has officially unveiled the all-new KB399 and lightweight KB399 ES (Edizione Speciale) at EICMA 2026 in Milan, establishing an ultra-exclusive, lightweight supersport weapon built around Kawasaki’s high-revving 399cc inline-four powerplant. Delivering 77 PS (56.6 kW) at 14,500 rpm—rising to 79 PS (58.2 kW) under full ram-air pressure—the Italian-crafted machine channels Rimini’s boutique chassis heritage into an accessible sub-500cc supersport footprint.

Positioned alongside the flagship WorldSBK-derived Bimota KB998 Rimini, the KB399 reimagines the platform-sharing synergy between Rimini and Akashi, pairing Japanese mechanical reliability with hand-finished Italian exoticism.

Screaming 399cc Inline-Four: Akashi Power, Rimini Refinement

The mechanical heart of the KB399 is borrowed from the Kawasaki Ninja ZX-4RR, featuring a 399cc liquid-cooled, 16-valve DOHC inline-four engine with a high-compression 12.3:1 ratio and a stratospheric 15,000 rpm rev ceiling. Bimota engineers recalibrated the engine management mapping via custom ECU parameters, optimizing throttle sensitivity across mid-range transitions while retaining a dedicated 47 PS (34.5 kW) A2-compliant restrictor package for European tiered license holders.

Exhaust gassing exits through a bespoke, standard-fitment titanium Akrapovič silencer specifically developed for the KB399 chassis, shedding unsprung mass while sharpening exhaust acoustic resonance. Power is managed through a bidirectional quickshifter, multi-stage Kawasaki Traction Control (KTRC), selectable power modes, and an electronic slipper clutch that eliminates rear-wheel hop during aggressive track downshifts into downhill hairpins.

Bimota KB399 ES Cockpit and Carbon Bodywork

Trellis Geometry, Showa Dampers, and the Up-Spec ES Kit

While Akashi supplies the engine block, the rolling chassis is pure Rimini craftsmanship. The KB399 abandons mass-production cast steel perimeter frames in favor of a hybrid composite chassis: a high-tensile tubular steel trellis front cradle bolted directly to CNC-machined billet aluminum rear swingarm pivot plates. Wheelbase spans a compact 1,380 mm, providing razor-sharp turn-in agility on tight European circuit configurations.

Suspension on the standard KB399 employs a 41 mm inverted Showa Separate Function Fork - Big Piston (SFF-BP) with adjustable preload and rebound damping, paired with a Showa Balance Free Rear Cushion (BFRC-lite) gas-charged monoshock.

For discerning track-day purists, the up-spec KB399 ES (Edizione Speciale) swaps the rear unit for an Öhlins STX46 fully adjustable damper, replaces fiberglass fairings with autoclaved pre-preg dry carbon fiber bodywork, and incorporates CNC-machined billet triple clamps and footpeg rearsets. Braking on both iterations is handled by top-tier radial-mount Brembo Stylema monobloc calipers clamping twin 290 mm floating front discs, operated by a radial Nissin master cylinder.

Technical Comparison: Sub-500cc Supersport Architecture

Specification Bimota KB399 / ES Kawasaki Ninja ZX-4RR Aprilia RS 457
Engine Architecture 399cc Inline-Four, DOHC 16V 399cc Inline-Four, DOHC 16V 457cc Parallel-Twin, 270° Crank
Peak Power (Ram-Air) 79 PS (58.2 kW) @ 14,500 rpm 80 PS (59 kW) @ 14,500 rpm 47.6 PS (35 kW) @ 9,400 rpm
Peak Torque 37.8 Nm @ 13,600 rpm 39 Nm @ 13,000 rpm 43.5 Nm @ 6,700 rpm
Chassis Construction Steel Trellis + Billet Aluminum Plates High-Tensile Steel Trellis Dual-Beam Aluminum Twin-Spar
Front Suspension 41 mm Showa SFF-BP Inverted Fork 41 mm Showa SFF-BP Inverted Fork 41 mm Inverted Preload Adjustable Fork
Rear Damper Showa BFRC-lite / Öhlins STX46 (ES) Showa BFRC-lite Gas-Charged Monoshock Preload Adjustable
Front Brakes Dual 290 mm Discs, Brembo Stylema Dual 290 mm Discs, Radial Nissin 4-Piston Single 320 mm Disc, ByBre 4-Piston
Estimated EU MSRP €18,500 (€22,000 ES) €10,299 €7,199

The Rider’s Trade-Off: High-Revving Exoticism vs Bottom-End Utility

The mechanical compromise of the KB399 centers around power delivery characteristics and cost-of-ownership economics. Unlike modern middleweight twins such as the BMW F 450 RR that produce tractable mid-range drive from 4,000 rpm, the screaming 399cc four-cylinder requires riders to maintain engine speeds above 10,000 rpm to exploit its mechanical sweet spot. In urban commuting or slow Alpine hairpins, the rider must work the 6-speed gearbox continuously.

Furthermore, at an estimated European retail price tag approaching €18,500 for the base model and €22,000 for the dry-carbon ES edition, the KB399 commands nearly double the investment of its Kawasaki donor platform. Buyers are paying exclusively for boutique Italian assembly, weight optimization, and peerless collector prestige.

“Our objective with the KB399 was not to chase displacement inflation, but to distill pure Grand Prix-level handling dynamics into a lightweight, high-rpm format where chassis precision dictates lap times rather than raw horsepower.” — Bimota Technical Design Department, EICMA 2026.

What We Know / What’s Still Unclear

What We Know: - Homologation: Euro 5+ emissions compliant with full European road-legal status and an available 35 kW A2 restrictor map. - Hardware: Standard titanium Akrapovič silencer, Brembo Stylema calipers, and Showa SFF-BP front suspension. - ES Upgrades: The Edizione Speciale adds an Öhlins STX46 shock, carbon bodywork, and billet aluminum jewelery.

What’s Still Unclear: - Production Allocations: Final production run quantities have not been confirmed, though Rimini estimates fewer than 500 units worldwide annually. - Exact Curb Weight: Official verified kerb weight figures with all fluids and 90% fuel capacity remain under homologation review.

Media citation: Editorial outlets and forums may quote excerpts with attribution and a link to Throttle Times.

Official source: https://www.bimota.com/nl/nl-nl/kb399

Reporting via: visordown.com, moto.it