While Ducati has made V4 roadbikes before – the Apollo and Desmosedici RR – its decision to ditch its signature V-twin for its mainstream top-of-the-range superbike next year represents a quantum shift in the firm’s way of thinking.
But don’t be concerned that Ducati has simply joined the herd. The new Desmosedici Stradale V4 roadbike engine it revealed on the eve of the Misano MotoGP weekend is still far from a run-of-the-mill design.
With the engine now public, it’s a waiting game to see more of the bike it will be fitted to. It’s set to be revealed at the EICMA show in Milan this November, but no doubt we’ll see plenty more teasers from Ducati in the meantime.
Fired up
As well as the unusual size, the Desmosedici Stradale breaks with the norm by using a reverse-rotating crankshaft. While that needs an additional jackshaft in the transmission to get the chain turning in the right direction, it means the engine counteracts some of the gyroscopic forces of the wheels, making the bike turn faster. It’s also claimed to help keep the front wheel down under acceleration.
More strangeness comes in the twin pulse firing order. The ignition fires at 0°, 90°, 290° and 380° and the crankshaft angle is 70°. That means the spaces between the power pulses are 90°, 200°, 90° and then a long 340° gap. It’s the same arrangement used on the Desmosedici MotoGP bikes, and will give the Stradale a distinctive drone.
Numbers
Surprisingly, 1103cc is the streetbike’s capacity. Of course, Ducati will add a sub-1000cc, short-stroke version of the engine in due course, which will power a homologation-special R version of the new V4 roadbike to allow it to race in the World Superbike Championship. But rival 1000cc road-going superbikes are instantly at a 10 per cent capacity disadvantage compared to the new Ducati.
That capacity comes from an 81mm bore – matching the MotoGP Desmosedici’s – and a 53.5mm stroke. The smaller, 1000cc version will be achieved with a 5mm stroke reduction to 48.5mm, keeping the same bore.
Power from that 1103cc mill is pegged at over 155kW at 13,000rpm. Torque is arguably even more impressive, as Ducati says it will achieve more than 120Nm for a 3500rpm band between 8750rpm and 12,250rpm. And with its radically-high 14:1 compression ratio, you’ll be glad to hear Ducati has fitted knock sensors to all the cylinders.
Heritage
Then, of course, there’s the Desmodromic valve system. Familiar to all Ducati fans, it dispenses with valve springs in favour of cam-operated rockers that mechanically close the valves. Except on this Desmosedici Stradale, of course, there are 16 of those valves rather than the four or eight that you’d find on a V-twin. On the new engine, the cams are driven by a combination of chain and gears rather than belts.
Despite double the cylinder and valve count of the old Superquattro V-twin powering the Panigale, the Desmosedici Stradale engine is just 2.2kg heavier than that motor, coming in at only 64.9kg.
That means the bike in which it finds itself should be just as light as the outgoing Panigale 1299.
New ground
A variable-length intake system with 52mm oval throttle bodies helps give a wider spread of torque. Although a familiar idea, it’s the first time Ducati has used such a set-up. Of course, those throttles will use ride-by-wire and feature the usual array of riding modes.
A semi-dry sump arrangement helps keep the engine light and compact, and no doubt aids Ducati in its quest to mount the entire Euro4-legal exhaust system in the new bike’s bellypan. There are no fewer than four oil pumps – one to deliver oil and three to recover it.
A new six-speed, quick-shift-equipped transmission and a hydraulic, wet, slipper clutch get the engine’s power to the contact patch.
Despite all its technology, the Desmosedici Stradale’s service intervals are surprisingly long. Normal services are at 12,000km or 12 months, while those 16 valves need their clearances adjusting at 24,000km.
By Ben Purvis
