The Australian Drysdale 750 V8 remains a true legend. Alan Cathcart took the superbike around Broadford, two-years into development. Words: Alan Cathcart Photos: Paul Barshon...
The Drysdale 750 V8 is an engineering masterpiece and an important part of Australia’s automotive history. When I rode it I didn’t know what to expect, but after a few laps back in 1999, I was left stunned at just how well the V8 handled the small track, Broadford.
Visitors to Britain’s Donington Park race circuit for the World Superbike round in 1999 probably didn’t realise there was an example of Australian engineering ingenuity on view, alongside Troy Corser’s on-track riding expertise.
You had to visit the Circuit Museum to find it, but there alongside the exotic extravaganza of Formula 1 racing cars down the years, sat a new addition to the Donington display – the Dryvtech 2x2x2, a two-wheel drive, two-wheel steer, two-stroke enduro bike built in Melbourne back in 1990 by free-thinking free spirit Ian Drysdale, an exponent par excellence of Australia’s can-do doctrine.
“I became the first person outside the Drysdale Motorcycle Co. test team to throw a leg over the barely completed eight-cylinder bike at the Calder Park test track in June ’97”
But the Dryvtech, though ingenious, was just a taster for 40-year old Drysdale’s technical tour de force – the design and construction of his own 750-V8 sportsbike. When I became the first person outside the Drysdale Motorcycle Co. test team to throw a leg over the barely completed eight-cylinder bike at the Calder Park test track in June ’97, my ride on a machine bristling with potential provided a hands-on appreciation of the Drysdale team’s drive in making such a complex project achieve reality.
Two years down the road, ongoing R&D interspersed by Ian’s need to earn the funds required to fuel the next stage of V8 development by doing other, more arcane, engineering work – including acting as technical consultant to a Chinese motorcycle factory – crystallised the final specification of the Drysdale V8 road models.
A critical element in refining the design thus far was the construction of the world’s first-ever 750-V8 Superbike, for Motorcycle Motion Team riders J.J. O’Rielly and Andrew Willy to race in local events under a special dispensation allowing prototype one-off machines of Australian manufacture to take part. Waiving the volume-production homologation rule had been done in Italy for the past decade, to permit bikes like the Ducati desmoquattro and various Bimota models to be developed on the racetrack, while allowing Peter Goddard’s works V-twin racer to compete in WSC rounds.
The chance to ride the 750-V8 racer at the scenic, switchback Broadford race track 80km north of Melbourne, provided a hands-on update on two years of Drysdale development. At first I was all set to wear earplugs to ride the Drysdale – but then I realised I’d have bought tickets to the concert, but not heard the music play. Listening to the haunting howl issuing from the V8’s twin underseat exhausts as Ian warmed it up not only made the flesh tingle, it also provided a window on the world that Grand Prix racing may yet become once again.
Listen to Ian warming up the Drysdale 750 in this short video!
One reason why World Superbike scores with spectators over GP racing anywhere except Spain or Japan is The Sound of Music – and the V8 Drysdale is the same, only much more so. It’s the closest thing there is today to riding a 1950/60’s works GP racer, even more so than a 15,000rpm Honda or Kawasaki Superbike. Underlining that the day the music died with the introduction of noise restrictions back in 1976, compounding the restriction on the number of cylinders imposed in 1970, was a sad one.
You had to ride the Drysdale V8 like a two-stroke racer off the line or out of slow turns, winding it up on the clutch to coax it into the powerband and overcome the lack of inertia from the milled-from-solid crankshaft weighing just 5.5kg, which started life as a solid billet of metal scaling a massive 44kg!
Rather incongruously, the V8 starts on the button in pit lane, though the Kawasaki ZZ-R250 starter motor has to work pretty hard at spinning four times as many cylinders as it’s used to coping with normally, before the engine finally fires up and settles down to a trademark V8 burble at low revs. But then, as you blip the throttle to make it sing, you realise the eight 32mm Keihin racing flatslides Ian had fitted on the racer, compared to the CV Mikunis on the street prototype I tried two years prior, have quite a stiff combined action, plus the twistgrip isn’t a very fast-action one.
“We’ve tried several alternative return springs, and the lightest ones that would overcome the suction effect and actually close the throttle still have a stiff action… We’ve also tried larger cable wheels, for more leverage, but these slow the throttle action down too much. There’s just no way around the fact that eight separate throttle slides have to be opened at once, and that takes a lot of effort – making development of a compatible fuel injection system a priority, for the streetbikes as well as the racer”.
True to his word, Drysdale had been working on his own EFI system, using his design of F1-type rotating-barrel throttle-bodies, coupled with Bosch injectors and an Australian-made MoTeC ECU with software specially developed to cope with the high revs – as much as 17,000rpm – of the V8 engine.
But once you get used to the heavy, rather slow throttle action, the flatslides currently fitted to the bike give strong pickup, with quite a bit more power on tap than on the CV-shod prototype I rode two years prior, the muscular, lumpy V8 motor picking up revs so effortlessly before smoothing out at higher rpm to deliver its haunting, high-pitched howl.
Get the V8 turning above 9,000rpm and the Drysdale sings sweetly as the reading on the multi-programme PI digital tacho rushes effortlessly towards the revlimiter, which had been lowered to 14,000 revs for this outing, with the engine being fresh off a rebuild and needing to be run in. But even tapping the gearlever at 13,500rpm to hit a higher ratio on the extractable, cassette-type, six-speed cluster, leaves the engine still squarely in the meaty power band above 11,000rpm and running as smooth as silk yet strong as steel back to the redline, with a level of performance that I’d honestly put at about the same as a well set-up Ducati 916SP or Suzuki TL1000R.
That means around 115bhp at the back wheel at 13,200rpm – in line with Ian’s claims for 140bhp at the crank, but with added music! – but with unexpectedly good midrange punch, which on a bike like this means anywhere from the five-figure rev mark upwards, though it will pull cleanly out of a turn as low as six grand.
The only downside to the performance was a pretty big flatspot around 8,000rpm, which was a bit difficult to work around on a tight track like Broadford with so many slow turns, where on the gearing fitted I could only just grab fourth gear on the top straight – third would have been all that was possible if I’d been able to rev it right out to 16 grand. It’s not really fair to criticise a bike like this for being a bit of a handful round a track it’s not at all built for – it’s rather like riding Mick Doohan’s NSR500 at the Sachsenring! – and I’ll bet that at big tracks like Assen or Monza or Phillip Island, keeping the V8 racer on the pipe would be much easier.
“Ian said he had an extra 8hp on tap just by shortening the intake stubs and bellmouths to the maximum at the expense of an even bigger hole in the powerband”.
“This is exhaust related,” he says, “and part of the engine management R&D we’re doing is to develop a fully-mapped EFI package with compatible intake lengths and exhaust system, which will make the bike fuel properly. We know what has to be done, and mapping the fuel injection correctly will be a big factor in getting it to run cleanly, as well as strongly.”
Getting the racebike to run cool enough with the extra power on tap entailed junking the underseat radiator of the street prototype – the V8 engine’s bulky architecture prevented a sufficient volume of high pressure flow of cooling air from reaching it – and replacing it with a pair of front-mounted radiators, which helped keep engine temp down to 75°C on a hot summer day at Broadford.
After initial oil-surge problems spun a bearing on the crank at the Oran Park 6-Hour race in 1998 (resolved by baffling the sump), the Drysdale V8 motor had proved fundamentally reliable since then, says its creator – though we had a couple of minor hiccups on my test day, one when the clutch circlip popped out (easily fixed), the other caused by Ian forgetting to switch the fuel pump on for one of my four sessions, meaning I coasted to a halt at the first turn with a dead engine.
Two 12V batteries in the nose power the Vance & Hines Powerpak digital ignition made to Drysdale’s spec by the American tuning house – “They were very helpful once we assured them that the specified redline of 17,000rpm was correct!”, says Ian – which replaces the two Yamaha CDI black boxes fitted to the street prototype, and is programmable for four different YZF600-based advance curves and revlimiter settings. Drysdale hopes to retain the V&H Powerpak in conjunction with the EFI, because he says it works so well.
The Drysdale uses as large a number of Yamaha proprietary parts as possible to allow customers around the world to source spares easily. So the 750-V8 racer uses two FZR400R 16-valve cylinder heads mounted on a horizontally-split crankcase, specially designed by Ian (himself a qualified draughtsman) to incorporate the blocks of each bank of cylinders in the upper crankcase half, for added rigidity.
The two banks of cylinders are set at 90-degrees to each other for perfect primary balance, and with the central chain camshaft drive of the Yamaha slantblock engine format retained, Drysdale has been able to reverse the camshafts and rotate them backwards on the rear set of cylinders, while those on the front bank, as well as the crankshaft, all run forwards. Yamaha parts retained on the 56 x 38mm 749cc engine include conrods and pistons (eight of each), all 32 tiny valves (21mm inlets/19mm exhausts) and all four camshafts, with cam drive taken directly off the crank.
Whilst I’ll admit I went to Broadford prepared to worship at the altar of multi-cylinder engine technology, accompanied by the magical strains of V8 music, I ended up being at least as impressed with Ian Drysdale’s talents as a chassis designer as I was with his work as a two-wheeled concert promotor. The TIG-welded tubular steel spaceframe that locates the V8 engine is built from ERW mild steel, with Ducati-style triangulation on the side spars and a distinctive loop backbone made from oval-section steel tube. The result weighs 11kg (not including the Kawasaki ZZ-R1100 alloy swingarm) – a little heavy, but perhaps inevitably so, with the engine forming only a semi-stressed underslung component.
To keep the V8’s wheelbase down to a manageable 1415mm, the Öhlins rear shock is located crossways in front of the rear wheel, and operated by a rising-rate bell-crank linkage similar to the one on Yamaha’s YZR500 GP racer two decades prior. With the crankshaft of the V8 motor already 20mm further forward relative to the centre line of the wheelbase compared to a YZF750’s, there was already surprisingly good weight distribution for the V8 motor scaling 65kg complete, but locating the batteries up front on the racer has the benefit of loading up the front wheel weight-wise, for a 53/47% layout.
As I settled aboard the bike at rest in pit lane, I noted not only how the riding position isn’t quite as stretched out as before, but that the rear ride height is also definitely taller than on the prototype streetbike I rode two years prior. This not only helps further increase front end weight bias, it also sharpens up the steering geometry for track use which, with a static 24-degree head angle and a hefty 108mm of trail, is definitely on the conservative side by sportbike standards – even if identical to Yamaha’s YZF750 sportbike, which is where Ian got it from.
“I remember already being impressed by the way the Drysdale V8 steered the first time I rode it, but that was on the relatively wide-open spaces of Calder Park”.
However, the first flying lap at Broadford tells you what an unexpectedly good handling package the bike has now been refined into by its creator – it belies its V8 bulk by steering as cleanly and sharply as a 750 four, turning precisely into the apex of a turn without falling suddenly over on its side, as you might expect from such a big, bulky bike.
Broadford has a couple of turns that pose a stiff exam for front-end grip, like the last turn onto the pit straight, or the downhill hairpin at the end of the top one, where you must commit to the blind entry and be ready for the track to fall away beneath you on the exit as you switch the power on. But the Drysdale passed the test with flying colours, the front-end planted to the ground thanks also to the works-spec front slick kindly donated by the Dunlop race service when the Drysdale performed some demo laps at the Phillip Island World Superbike round.
The bike not only stops very well, with the six-pot Nissins giving lots of bite, but really, it steered surprisingly easily and precisely, too, with impressive handling for what when you see it you think is going to be a beefy, tiring bike to lug around a tight track like Broadford.
It stays on line exiting a turn under power, with no undue understeer, and the liquid-smooth power curve at higher rpm ensures there are no steps in the delivery ready to unhook the back wheel when you get hard on the gas exiting that downhill turn. Nor again when you accelerate hard out of the uphill turn before it, with the front wheel waving in the air as you crest the rise: it felt fast, but not fickle. But the rear Dunlop was ready to walk under power, chattering slightly as you fed the revs in, and you could feel the Öhlins shock bouncing back abruptly off bottom.
It felt like too little rebound damping, for sure – but also I think the rising rate linkage had too steep a curve, and maybe the spring was too soft for my weight. A more linear rate linkage would be better for street use, for sure – but on the race track what’s needed is a good day’s sorting session with a suspension technician on hand.
At the end of the day, what’s most impressive about the Drysdale V8 is that this is the product of one man’s genius – plus his own drive, determination, technical expertise and ability to charm countless friends into wanting to join the party, and to help him make it all happen. Ian Drysdale had the vision to conceive the 750-V8 in the first place, as a modern-day testament to the legendary Moto Guzzi V8 GP racer, he assembled it in his workshop together with his team of fellow visionaries, and has used his own time, money, vision and expertise to make a dream come alive by being made into metal.
Check out Jeff’s article on the Drysdale 1000cc V8, the bigger sibling, here…
Drysdale 750 V8 Specifications
Claimed Power: 140bhp@15,800rpm
Dry Weight: 185kg
Engine: Liquid-cooled DOHC 32-valve 90° V8 four-stroke with four valves per cylinder and central chain camshaft drive, 749cc, 56 x 38mm bore x stroke, 11.5:1 compression, 8 x 32mm Keihin FCR flatslides, Vance & Hines Powerpak programmable electronic CDI
Gearbox: 6-speed extractable cassette with gear primary drive Clutch: Wet, Multi-plate
Chassis: Tubular-steel spaceframe with oval-section loop backbone
Suspension: Front: 41mm Yamaha inverted telescopic forks. Rear: Extruded aluminium swingarm with single Öhlins shock and bell-crank progressive rate linkage
Brakes: Front: 2 x 320mm discs with six-piston calipers. Rear: 1 x 245mm steel disc with two-piston caliper
Wheels & Tyres: Front: 120/70-17 Dunlop KR106 radial on 3.50in. Yamaha cast aluminium wheel. Rear: 180/55-17 Dunlop KR108 radial on 5.50in. Yamaha cast aluminium wheel.
Head angle/trail: 24 degrees/108mm
Top speed: Over 280 kph/175mph
Manufacturer: Drysdale Motorcycle Co., Springvale, Victoria, Australia