Bimota DB1

Ducati 750F1 vs Bimota DB1

EVEN THE COPS WERE IMPRESSED. Hurtling round a bend or circulating a roundabout repeatedly for a photographer invariably attracts the attentions of the police. We'd obviously been spotted by the two occupants of the Range Rover several tunes before they put in an appearance. These two guardians of the law weren't about to write any tickets, they were far too interested in the machinery we were on. But then you couldn't fail to be impressed by our choice of machinery. Both the Ducati 750F1 and Bimota DB1 are exotic motorcycles in the true sense. They both began life as an out-and-out racing exercise, supplies are limited (Sports Racing, the Bimota importer, have an allocation of only 24 bikes this year, while Moto Vecchia await their next batch of Fls to restore their depleted stock) and they both look stunning.

Five minutes later we were riding for the benefit of the photographer again, but this time we had a Police Range Rover stuck sideways on our tails as a broadly grinning driver tried to swing its unwieldy bulk through the bends as quickly as the bikes. It look a little while to get used to the idea of tilting the bikes into each bend with your knee dragging across the tarmac and the centrestand scraping away while under official scrutiny, you don't normally come away from encounters like that with your license intact. But riding the 750F1 and the DB1 it all somehow seemed rather appropriate.

Just look at them: these bikes have got class. The DB1 is so small and it flows. The all-enveloping pearlescent bodywork sweeps forward and down from the tail light, around the 750 Pantah engine's sump, then curves up to meet the petite screen. Plenty of other bikes these days can boast the same sort of GRP acreage, but the Bimota is the only one to really mould the constituent parts into one complete package. The paintwork has the touch of genius, simple and patriotic with four red and green stripes converging at the front. It's without doubt the most beautiful motorcycle on the roads today.

The 750F1 is equally patriotic, it looks like someone has just draped the Italian tricolour across its side. Three broad slashes of colour leap out at you. The whole bike has a slabby look, the tail unit extends downwards a long way then stops short behind the rear carb, and the tall screen is reminiscent of a shopping bike. It looks more basic than the DBI; the chassis and the engine are exposed to the elements. It is functional design at its most obvious.

Both bikes use the Ducati Pantah engine as their motive force. From its introduction in 1977 the Pantah V-twin has grown in size from 500cc to 600 and now 750. Even nine years after its launch it's unique in motorcycling  for using toothed rubber belts to drive the camshafts. The 748cc has been achieved x 61.5mm from the original 74 x 58mm, and to cope with the extra power an oil cooler pumps up the lubricant from the 9 liter sump. Neither machine makes any outrageous horsepower claim, 75hp being the official figure.

A nine-year-old engine design with air cooling can hardly compete with the That combination of latest water- and oil-cooled Japanese colour Hneand motors no what still makes these engines ' desirable is their solid mid-range punch. metal could only be Despite the fact that they both use the Italian same 36mm Dellortos that appeared on the first 500 Pantah, once you hit three grand on the tacho the flat power band takes you where you want to go in a totally relaxed manner - but fast. In all honesty these engines would be perfect for a touring bike, there are no holes or leaps in their power delivery and they don't have the frenetic feel of a four. But mounted in these bikes they offer an attractive style of sporting performance for those who've progressed beyond the scream and crackle of two strokes and the wail of multicylinder.

Basically, the engines in these bikes are identical, the only real differences occur in the inlet and exhaust systems. The DBI sports Bimota's own twin black silencers which are just that, bereft of the traditional Italian bark. The 750F1 sounds more in tune with the bike's image as a race replica with a two-into-one exiting on the left side of the bike leaving a noise signature that no one with any soul could complain about.

On the inlet side the 750F1 draws in air, dust, rain and small mammals through a pair of meshed bell mouths. There may not be any concessions made to engine longevity but at least the vital oxygen doesn't have to follow the same tortuous path as it does on the DB1. The single air box is tucked behind the rear cylinder between the frame rails. From there it's a relatively short distance into the rear carb. But to reach the front pot a tortuous tract has to be plumbed between the frame rails, electrics and the rear cylinder.

The chassis for both bikes follow the same basic principles using the engine as a stressed member thanks to its very strong gravity diecast crankcases. The Ducati frame is a fully triangulated chrome -moly trestle, a development of Ing Taglioni's F2 design. The round section swingarm is pivoted in the rear of the crankcases before coming up to meet the cantilever rear suspension. As you'd expect, a Marzocchi shock resides here with screw adjusted preload and provision for charging the damping oil with air via a Schraeder valve at the base of the unit.

Five years at Ducati must have influenced Ing Martini, and he would have found it hard to depart from the same general design brief. As it is he has developed the theme somewhat. The Bimota chassis, while still a chrome-moly trestle, is more compact and doesn't have to kink frame rails to clear the engine as on the Fl.

As pioneers of the monoshock layout in the 70s it's no surprise that another single Marzocchi spring and damper can be found buried deep within the machine. As on the Fl, this uses a screw adjuster for the preload but with a remote adjuster mounted on the swingarm for compression damping. And it's rising rate, too. The swingarm differs as well, it's box-section steel and uses eccentric adjusters to maintain chain tension. Again there are broad similarities between the two bikes at the front end -Marzocchi forks, fully floating Brembo discs, 16-inch wheels - but there are detail differences. The DB1 uses the latest 41.7mm MIR forks with four-position rebound damping adjustment on the right leg and a design that allows an infinite number of independent compression and rebound damping set ups just by changing the oil in each fork leg. Left leg for compression damping, right one for rebound.

The previous generation of 40mm Marzocchi forks appears on the Ducati with five-position preload adjustment atop each leg and three-position rebound damping on each leg alongside the spindle.

Both bikes carry 280mm floating discs up front which rustle disconcertingly on their dowels at low speeds, but the calipers are different. The four-piston Goldlines on the DB1 pull you up every time without any sort of fade or drama, but if you brake in a bend then they pull the whole bike upright with a vengeance. You have to learn to keep the. pressure up on the inside bar if you want to get round. The Fl has more simple dual-piston offerings. On the limit they'll put you in front of the Bimota just when you don't want to be. A lack of Goodridge nosing and inconsistent pad quality may be to blame.

Bimota specialise in exquisitely detailed machining work and the DB1 shows it. The quality of milling on the top yoke and clip-ons would gratify a Swiss watchmaker, and turning alloy master cylinders into a fashion accessory by mounting them on top of the fork legs shows an originality too often lacking in motorcycle design.

The Duke has its moments with pleasingly flat alloy yokes and foam-mounted instruments a la GSX-R750, but at an angle that makes them legible to the rider, Crouched down on the DB1 it's hard to tell to within 500revs or 10 kph what's going on from the almost horizontal clocks.

Get close to a DB1 and size, or the lack of it, is what will strike you most. It's tiny, a good eight inches lower than the Ducati. But that doesn't mean those over 5ft 7in will automatically have to buy the 750F1. Although Ing. Martini didn't make many concessions when he built this motorcycle, the tank cutouts allow the longest legs to tuck out of the airstream while the rear of the tank will support you and the petite screen allows the wind to take the weight off your wrists. Admittedly there is an ideal size of rider, about 5ft 6in, who will suit every curve of the bodywork, but even taller pilots found they could mould themselves into the DBFs lines to a certain extent.

Most motorcycles are time consuming to disassemble with sundry nuts and bolts, which if not impossible to undo, always seem to be left over after the rebuild. Not so with the Bimota. To remove the nose fairing undo two 5mm Allen bolts, twist four Dzus fasteners a half turn, pull out the indicators' connectors and, spreading the edges slightly, pull the section straight off. Four more Dzus fasteners and the bellypan drops away. Then all that holds the main seat/tank unit on is a quartet of 8mm Allen bolts, complete with beautifully turned-up spacers for the front pair, and a bayonet fitting to the rear light. Once you've removed the gas cap it just lifts away. Big Kawasakis and BMWs can sometimes take almost an hour to lay  bare, the Bimota takes five minutes.

Once the tank with its two vacuum taps and fuel warning sender has been slipped off, the bikes compactness is even more obvious. The chassis is so tight, not a fraction of space has been wasted within its perimeter. No ancillaries have been allowed to protrude and spoil the lines, unlike the Fl where the battery's location at the extreme rear of the frame necessitates a heavy looking, angular tail section. On the DB1 the battery and the coils sit above the front cylinder, while the top of the rear shock linkage and the airbox are crammed into the remaining space behind the rear of the engine. The whole concept looks good on paper and looks even better in real life...until you use the engine seriously.

Nowadays, as well as dynoing our test bikes we also speed test them at the Bruntingthorpe Proving Ground in Leicestershire, and it was there we headed with high hopes and the Bimota. They were dashed after the first few runs; a mean top speed of 116mph was hardly impressive for a sports 750. Try as we might we couldn't squeeze any more out of the bike. In fact it got worse. After four or five runs the bike wouldn't take full throttle and had to be nursed towards the redline at 8500.

Obviously things weren't right, so the next trip was down to Motodd's rolling road for a bit of investigation. The power figures after the first runs were depressing; 51.1hp at 7500rpm wasn't going to set the world alight. The engine was pinking around maximum torque at 4500 and misfiring at 5500. Touching the electrics

gave us a clue - they were red hot - apart from being difficult to get at. How long will the battery or coils last in that sort of heat? And how can the engine produce any sort of power in that sort of heat?

Basic physics has it that the thermal efficiency of an engine is improved the greater the difference in temperature between the incoming charge and the exhaust gases. Kawasaki went to the trouble of designing an airbox with intakes beneath the headlight to make sure the GPZ1000RX always gets relatively cool air, and that bike is the most powerful machine we've ever tested. So having a tiny intake into the airbox at the back of a warm engine bay wasn't going to help. To make matters worse, a hot engine breather exited into the bottom of the filterless box.

So the engine was ingesting hot, sticky air; obviously the easiest mod was to junk the air box. Rather than strip the entire bike or take a hacksaw to the frame, we left the box in place and removed the trunking to each carb instead. A pinking motorcycle on the dyno is a recipe for disaster so we squinted down the plug holes at the piston crowns. The front pot was about right but rear was dangerously pale with the dreaded 'death ash' deposits sprinkled around. Upping the jet from 135 to 145 alleviated the situation.

Who'd have thought such simple mods would've so improved a bike? Breathing straight into the carb throats, the DB1 now put out exactly 57hp at 7500 without a trace of a misfire. We guessed that the mismatched inlet tracts between the carbs had been affecting their pulsing in the mid-range causing the flat spot. And the fact that the fuel flow on the previous test had remained constant after 7000rpm indicated that the airbox stifled the inlets giving more power at less than full throttle. As it was, by bypassing the airbox and changing the jetting we'd reaped a 12 per cent power increase improved torque spread.

After the Bimota's voyage of discovery on the dyno, the Ducati's test was plain sailing. Six gee gees better, the Fl put out 63hp at the peak of a luscious spread of power at 7500rpm. Another flat torque curve, staying close to the 50.2ftlb maximum at 4500 revs, and a specific fuel consumption in the mid 50s indicated a nicely sorted engine with easy tuning potential, albeit at the expense of flexibility.

Unlike the other importers, picking up a Bimota doesn't just involve the usual tedious journey through London's suburbs, Steve Wynne's Sports Racing concern resides in Bollington just outside Macclesfield. There are some great roads across the Peak District in that part of the world and Julian claimed the privilege of collecting the bike and bringing it down to London. When he arrived the rest of the office showered him with questions about the bike's performance and handling. We'd all suffered a little from the feverish excitement and expectation for this bike that had gripped our editor's imagination over the last few months. Strangely, his responses were rather subdued. Yes, it handled okay, the engine was fine and the brakes good. Okay, fine? This wasn't what we expected to hear, we're talking about a Bimota here.

My first ride on the bike was of necessity not in the most ideal of conditions. An out-and-out sports bike can hardly be expected to show well in London's city centre. But some of its traits were quite disconcerting. Below 50mph the DB1 refused to go in a straight line. It felt like it had ratchet head bearings. A motorcycle actually follows a series of balance correcting curves as we continually use the steering to follow a straight course. On the DB1 you found yourself fighting the bars as the bike veered first one way then another. When there's a solid wall of traffic a foot away on both sides this can be unnerving to say the least. Investigation inside the fairing revealed a steering damper wound up to maximum. Backing it right off solved the problem, but its location tucked away inside the fairing means it's not possible to adjust on the move.

But once out on to some relatively clear, open stretches some of the Bimota's attributes began to shine through. It carries its weight low and feels even lighter than my 250 Gamma racing bike. A wheelbase of 1380mm and a 25° rake angle combine with this svelte form to give steering that above 70mph is so quick but effortless. Attack fast sweeping bends with some forceful riding and the Bimota will reward you with a fast, smooth rhythm. Use the Goldlines hard with just two fingers enough to elicit a stoppie, then tip straight into each corner. The DB1 responds to this sort of treatment by sticking to the line every time. But throw in the more usual bumps and holes along with a series of slow bends and the DB1 begins to suffer.

For a start I don't know whether it's the tyres or the suspension but on slow corners the DB1 feels incredibly unstable. I'd have been happier on a Goldwing at times. Those 60-Series Pirellis which the Italian firm are claiming as radials work very well at higher speeds, although they aren't perfectly matched to the rims leaving the last 5mm of the tread unused on both tyres. But having such a wide, low front makes the transition from straight ahead to canted over very sudden at urban speeds. Come to a roundabout and you thru penny bit round it as the bike drops in then picks itself up again. I almost went for a trails dab one time. The brakes are incredibly powerful without any sort of fade but then you hit a bump and because you're traveling at less than the legal limit the suspension totally fails to absorb the shock and the bike adds head shaking to its repertoire.

Ride the rear end over the same undulation and your backside is kicked out of the seat by the Marzocchi's harsh response se. Spring and damping rates were too stiff for the road. This was with the lowest damping setting and preload wound as far back as the chewed up C-rings would allow.

For two bikes so similar in many areas -engine, suspension, brakes - the Fl and DB1 couldn't have handled much more differently. A DB1 owner will feel like he's mounting a horse when he gets on the Fl. It's tall and thin and only carries 5kg more weight than the Bimota.

When he arrives at the first corner he's in for some more surprises too. Racing (remember this bike's an Fl replica) and fashion dictated a 16-inch front wheel. But Ducati where loath to lose their traditional stability so they kicked out the rake to 28° with a long 155mm of trail. Consequently our friend might And himself missing the apex and running in to the dirt on that first bend. The steering's much heavier than the Bimota's and needs a firm hand, but light weight, a 16in wheel and some body English mean you can change direction just as quickly once you've put in the initial effort. As it is the Duke needs the steering damper hidden in among the fairing brackets and frame tubes when heavy bumps set the front tyre kicking. Position four is normally good enough. The Ducati's behaviour is more consistent too; it'll behave in the same manner at 25 or 125mph. Pirelli's Phantoms help here. Their rounded profile make for a linear steering feel, not the tuck and grab of the DB1.

Round two at Bruntingthorpe: The DB1 sailed past the lights at 124mph, an eight miles per hour improvement, with it responding cleanly all the way into the redline at 9l00rpm. Better, but the Fl trounced it with a best of 131 at 8500rpm. Hurtling up and down I got to appreciate the Duke's high screen that leaves just you and the V-twin together in a bubble of still air. While you're still pulled down onto clip-ons, the tank doesn't rise up into your solar plexus like on the DB1 - and the seat's more comfortable. The aches don't get through, but vibration does. Above 5500rpm the tingle from the footrests becomes uncomfortable and even gets painful over long motorway hauls.

It may not be rising rate, but the Fl's suspension is more compliant than the DBl's plus easier to fine tune at the front. You could ride this bike through the bumps, not around them all the time. In short, it's more usable.

While the DB1 will appeal to the poseurs of this world and offers some great times it's too single minded. It was obviously developed direct from race-track experience. Ing Martini believes 'Five races are worth 100,000km of road testing.' But just as a circuit makes no concessions, neither does the Bimota. You've got to be prepared to ride it hard and I suspect £7500 is too big a block for most people's enthusiasm. It's still got the looks, but I'd only be willing to pay an extra SI500 for them.

The Fl has some serious style of its own. Attention to detail is a lot better than any previous Ducati. Cagiva are obviously taking a closer interest. Just look at the beautiful engraved alloy filler cap and the quality of the paintwork. This jewel isn't going to tarnish quickly. Add to that the fact that this motorcycle's performance is usable and you've got a winner. To be honest I much preferred the Ducati's handling to the Bimota's, so long the benchmark when it came to bends.

The DB1 seems to have dominated this test but that's because we tested and retested it as we solved some of its problems. The Ducati just performed well; exciting at times, but always satisfying. It proved itself an all-round motorcycle, and one that played on the emotions of the rider, just as the DB1 did before reality took over. The 750F1 is one of the few bikes on the road today that allows the rider to at least subvert reality in a riot of noise, colour and speed.

Source MOTORCYCLE International 1986