I love me a good underdog story, and the tale of the Bimota YB4 is nothing if not an underdog story. Despite the F1 championship being arguably the most important four-stroke class to manufacturers at the time, the tiny Italian operation nonetheless managed to dethrone Honda’s deep-pocketed factory race program with the mighty YB4.For the majority of the boutique outfit’s existence, Bimota has followed a simple yet successful formula: take a proven power plant, drop it in an advanced chassis, and then deck the thing out in top-shelf running gear and unapologetically Italian bodywork. Bimota’s YB4 followed this same recipe, wrapping Yamaha’s 749cc “Genesis” engine (that first debuted in ’85) in a lightweight twin-spar frame before racking on some of the finest components money could buy in the mid-late 1980s.
Though the three-quarter liter mill offered ample top-end oomph, the five-valve-per-cylinder engine left something to be desired in the mid and low-end departments. In an effort to remedy the perceived problem, Bimota’s team opted to augment and integrate a fuel-injection system for the YB4. The sub-400lb YB4’s impressive power-to-weight ratio was largely thanks to the bike’s frame; a lightweight aluminum perimeter chassis paired with a matching aluminum swing-arm. While perimeter frames on superbikes may be par for the course today, the same couldn’t be said in 1987, making Bimota an early pioneer in employing the structural layout.
In ’87 Bimota debuted the YB4 in the Formula One World Championship, putting an end to Honda’s half-decade-long reign of supremacy. The next year would mark the inaugural season of a new series called the “World Superbike Championship”. To comply with the new series’ homologation rules, Bimota produced a regulation-friendly 200 units — the minimum production number required to compete.
In ’88 Bimota campaigned a YB4 in the first ever WSBK season where Davide Tardozzi nabbed the top rung of the podium in WSBK’s inaugural race before going on to finish out the season in third overall, just behind Fred Merkel and Fabrizio Pirovano on their the much better-funded Honda and Yamaha factory rides. The following year Bimota cooked up another small batch of YB4 specimens, with the Italian outfit continuing to race — and punch well above its weight — against the rest of the competition coming out of Japan and Europe. In addition to its trick chassis and massaged, fuel-injected “Genesis” mill, the YB4 got top-of-the-line suspension from Marzocchi, and equally high-spec braking hardware from Brembo.
Produced for just two years, only 300 or so YB4 examples left the factory prior to the model being phased out. Supposedly originally owned by New Zealand’s Shanton Racing, this particular ‘88 YB4 IE factory kit racer was reportedly piloted by Andrew Stroud in WSBK’s debut season, as well as round three of the Swann Series at Phillip Island (Australia). After seeing competition toward the tail end of the ‘80s, this example has sat dormant, still wearing its Michelin slicks from when it raced in ‘88. Despite the vintage rubber, this YB4 has more recently received a thorough overhaul with the engine and brakes being freshened up. The sale of this track-only bike also includes a handful of unspecified spare parts, as well as “a selection of fuel injection computer cards for various tunes. (Yes, the days of floppy discs! Haha!)”.
To see Bimota’s late-‘80s Yamaha-powered WSBK racer in action (and to get a sense of what WSBK’s first year looked like…spoiler alert, it was awesome) I highly recommend checking out the the 1988 Manfield WSBK final — where this exact example finished in 13th in leg (race) 1 and 9th in leg (race) 2 — which someone has posted to YouTube in its entirety:
Aside from needing a new set of tires, this example — which is fitted with the kit YEC FZR750R engine and close ratio gearbox — is ready to hit the track (or more likely the stable of a collector). Like the Bimota SB2 that came before it, the YB4 was the bike to have upon its debut. On top of its race pedigree and competence on the track, the YB4’s relatively minute production numbers make finding examples today extraordinarily difficult, especially state-side.
Find this ex-WSBK 1988 Bimota YB4 IE (Frame number #00035) for sale here on RaceBikeMart in Sydney, Australia with a price of $31,660 (or £25,000).