Carole Nash
Content Writer
Published: 17th June 2008

Perhaps the final step along the evolutionary road for Bimota and their association with the 900cc Ducati V-twin engine.

Fitting the late 1990s 90 degree twin from the boys at Bologna transformed the DB machine, as the motor was much more reliable, and a bit more powerful, than its predecessor.

Using an ultralight chassis from its wacky styled Mantra machine, the Bimota DB4 offered the sports rider an exquisite combination of handling, noise and classic Italian panache. Sadly the recent financial difficulties of Bimota meant that production of the DB4 was limited to low numbers.

From the moment its motor fires up with a cacophony of V-twin sound from the side-by-side silencers behind your right boot, there´s something familiar about Bimota´s new DB4. It feels small, light, raw, basic – every bit a traditional Italian sportster.
This first model from Bimota under its new management is a very different bike from the radical two-stroke 500 Vdue whose mechanical problems drove Bimota to the brink of collapse. Now run by a group of businessmen headed by former Laverda chief Francesco Tognon, Bimota is fighting back the way it knows best.

This is not the first time that Bimota has looked to a lean and simple V-twin to help pull it out of the smelly stuff. Back in 1985, the sales success of the DB1, its first ever Ducati-powered model, rescued the firm from its first financial crisis. Now Tognon and his team are hoping they can pull off the same trick again with the DB4, which combines the engine from Ducati´s latest 900SS with a tubular aluminium frame similar to that of the wacky Mantra roadster.

As usual Bimota does not make any internal changes to the 904cc, air/oilcooled V-twin. Ducati uprated the old sohc two-valves-per-cylinder lump slightly for last year´s restyled 900SS, giving it new cams for slightly better breathing at high revs. Bimota adds its own twin-pipe exhaust system, and surprisingly replaces the Ducati´s new fuel-injection system with the previous model´s 38mm Mikuni carbs, complete with Bimota-designed airbox.

Chassis layout is almost identical to that of the Mantra, based around an oval-section tubular aluminium frame that weighs just 5kg. The cantilever swing-arm, which is also made of aluminium tubes, operates a diagonally mounted Ohlins shock. At the sharp end, 43mm Paioli forks are held at a steep 23-degree angle.

The first thing that hits you about the DB4 is how tiny it is. With a wheelbase of just 1370mm, seat height of 800mm and dry weight figure of just 165kg, it´s shorter, lower and lighter than Yamaha´s R6, let alone the 900SS. Even short riders will be able to plant both feet firmly on the ground, and you barely have to reach forward to the low clip-ons.

Like the 900SS, the DB4 won´t have much appeal to riders who demand power and speed above all else. The Duke´s claimed peak output is a weedy 80bhp at 7500rpm, and although the Bim´s free-breathing exhaust means it barks louder, it doesn´t have any more bite. Just like the 900SS, though, the DB4 combines punchy midrange with the old single-cam V-twin´s lumpy charm.

Bimota justifies the DB4´s use of carbs as retaining the DB series´ traditional simplicity. No doubt they´re cheaper, too. But during my ride on the hilly, twisty roads inland from Rimini, the Bim suffered from an erratic idle and a slight glitch that was occasionally noticeable when opening the throttle with just under 5000rpm on the tacho, suggesting the Mikunis needed better setting-up.

That didn´t prevent the DB4 from being brilliant fun. Its typical V-twin snatchiness at low revs cleared at about 3000rpm. There was good power from four grand and even more from about five, before the sohc motor began to run out of puff at eight thou, 1000rpm or so short of the limit. In the 60-110mph zone where you spend most time on the road it was seriously rapid, aided by its light weight and broad torque spread.

Acceleration tailed off above about 120mph, though with enough room, and its pilot hiding behind the low screen, it would probably get to a genuine 135mph. More power would occasionally be nice, but on these roads the Bim had plenty. Throttle action was light, the six-speed gearbox sweet, and the midrange grunt made for effortless clutchless wheelies.

Bimota´s reputation was originally based on its light, rigid chassis, and the DB4 lives up to that tradition. With such sharp geometry and so little weight the little twin could be chucked around with ease, flicking rapidly from side to side with minimal pressure on its bars. Yet apart from a slight tendency to be shunted off line by road imperfections, it was super-stable too..

Much of the credit for that goes to the suspension. The fairly firm, multi-adjustable Paioli forks gave good feedback and helped make this one of the sweetest-steering bikes on the road. And the Ohlins shock was excellent, keeping the rear end under control even when the Bimota was accelerating hard out of bumpy corners.

The familiar braking blend of 320mm Brembo discs and four-pot calipers had plenty of bite, while needing a fair bit of lever pressure. Pirelli´s super-sticky Dragon Corsa radials found grip even in the most slippery looking bends. My only cornering problem was that my right Size 11 sometimes tangled with the carbon-fibre exhaust shield, which is too close to the footrest.

Other carbon parts and the DB4´s patriotic red-white-green bodywork were finished to the high standard expected of Bimota, but not always achieved in the past. New boss Tognon is conscious that as a manufacturer of premium-priced bikes, Bimota´s quality must be impeccable. By Rimini standards the hand-assembled DB4 is competitively priced, but it´s still more expensive than plenty of much faster mass-produced machines.

The DB4 is far from the fastest bike in the world, its engineering isn´t state-of-the-art, and overall it´s hardly a leap forward from the excellent DB2 of a few years ago. But so what? It´s a stylish, quick, torquey, fine-handling and very enjoyable motorbike and one built from tried and tested components. Which makes it the ideal way to kickstart Bimota´s comeback.

If the DB4 is as successful as Bimota´s first Ducati-powered bike, it will go a long way towards restoring the firm to something like health following the disaster of the 500 Vdue. The DB1, designed by Bimota´s then chief engineer Federico Martini and released in 1985, hid a 750cc Ducati V-twin engine and steel trellis frame beneath swoopy all-enveloping bodywork. It was a big success for Bimota, with over 650 units sold including the later DB1 S and DB1 SR versions.

The DB2 introduced in 1993 was a very different bike that was powered, like the latest model, by the two-valves-per-cylinder V-twin from Ducati´s 900SS. Chief engineer Pierluigi Marconi´s DB2 was similar in concept and looks to the latest DB model, though it had a conventional steel trellis frame, and twin high-level silencers in the tailpiece.

Again the format proved successful for Bimota, who built over 400 units of the original model – big numbers by Rimini standards – plus a further 250 of the fuel-injected DB2 SR and “final edition” DB2 EF models which followed. The EF version was still being produced in small numbers last year.

Ironically the forkless Tesi, Marconi´s other Ducati-powered Bimota, was not part of the DB series and was far less successful. Despite consuming large amounts of development time and money before its release in 1990, the Tesi had problems and sold poorly, with fewer than 400 being produced before the model was dropped four years later.

The bike designated DB3 was better known as the Mantra: the strangely styled 1995-model roadster designed by Frenchman Sacha Lakic. The Mantra combined Ducati´s 900SS engine with a new oval-section aluminium frame, as used by the DB4. Although the Mantra´s outrageous looks met with a mixed reaction, the bike is still in demand. Bimota production restarted in November with 50 Mantras, taking the total to over 450.

Get Bimota motorcycle insurance for the DB4.


Vital Statistics
Engine oil cooled 90-degree V-twin
cc 904
Claimed power (bhp) 95bhp @ 12,000rpm
Compression ratio 9.2:1
Transmission Six Speed
Cycle parts
Front suspension 43mm telescopic Paioli, 120mm travel, adjustments for preload, compression and rebound damping
Rear suspension One Ohlins damper, 102mm wheel travel, adjustments for preload, compression and rebound damping
Front brake 2, four-piston Brembo calipers, 320mm discs
Rear brake Double-action Brembo caliper, 230mm disc
Front wheel 3.50 x 17in; cast aluminum Rear wheel
Rear wheel 5.50 x 17in; cast aluminum
Front tyre 120/70 x 17in Pirelli Dragon Corsa
Rear tyre 180/55 x 17in Pirelli Dragon Corsa
Rake/trail 23 degrees/91mm (3.6in)
Wheelbase 1370mm (54in)
Seat height 800mm (31.5in)
Dry weight 165kg (363lb)