Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/517599
VOL. 52 ISSUE 21 MAY 27, 2015 P97 Though there's still enough left in to be helpful, the new software settings for the RF/RR reduce engine braking below 6,000 rpm, so in braking for any of those several slow corners at Misano this allows you to just tap back two, three or even four gears in swift succession, and leave the electronics and slipper clutch to sort everything out with no fuss, and without any sign of instability or chatter, while you fan the clutch lever as you tip into a turn with everything under control. What—you have to use the clutch for downshifts on the Aprilia? Yes, I'm afraid so. Unlike its Ducati, BMW and Yamaha rivals there's no auto-blipper system on the new RSV4, an unaccountable omission on a bike that has always led the field in electronic assistance. "We have the technology, because it's on the Superbike racer," said Soatti rather shame- facedly. "But we are behind in bringing this to the street, though it will follow later this year." With the grippy new Misano surface and Superstock race rubber fitted for the launch I wasn't likely to get the front ABS kicking in anywhere round there, and noticed no subdued machine-gun rattle from the front brakes as I slowed from speed. at maximizing pressure to the intake ducts leading to the bank of four 48mm Marelli throttle bodies, each still fitted with twin injectors, one posi- tioned upstream of the throttle butter- fly, the other a newly revised top-spray device which, rather than being governed by engine revs, comes into operation only according to the degree of throttle opening—around 65 percent. The closer to the intake valve seat the injector is positioned, the better the throttle response, so Aprilia uses the lower injector all the time, then when you're accelerating hard, the second top injector comes into operation to satisfy the engine's demand for more fuel. Engine management on the RSV4 is entrusted to a new, more powerful Magneti Marelli ECU, but with Aprilia responsible for calibration of the software in-house. The RBW (ride- by-wire) throttle system uses a pair of servo motors—one for each bank of cylinders) to operate the throttles, which thus allows the fueling for each cylinder bank to be managed indepen- dently. In addition, a trio of different throttle maps is offered via a switch on the handlebar, though these have been renamed from before, and are now Race, Track and Sport instead of Track, Sport and Road. As before, there's a variable length intake system with a longer inlet tract length of 265mm from the lip of the velocity stack to the inlet valve seat, in order to optimize low-rpm per- formance. Then, when the Magneti Marelli ECU monitoring engine speed and the degree of opening of the RBW throttle, sees revs hit the cho- sen mark - now 11,000 rpm accord- ing to Soatti, rather than 9000 rpm before, in order to maximize midrange torque - it activates an electric servo motor to simultaneously separate the two halves of each of the four funnels, leaving the bottom halves in place to deliver a shorter inlet tract than before for extra performance at the 500 rpm higher engine speeds the new motor is capable of. The entire exhaust sys- tem has been completely redesigned, with larger 36mm diameter headers (up from 33mm) and it now has two oxygen sensors (one per cylinder bank), and revised electronic manage- ment of the butterfly exhaust valve. The RSV4's six-speed side-loading cassette-type gearbox uses straight- cut primary gears, and is matched to a ramp-type oil-bath slipper clutch, which permits the degree of slip to be altered by changing the angle of the ramps. The gearbox has a new choice of ratios to reflect the engine's increased power, and features a light- ened mainshaft, layshaft and primary drive plus narrower gear pinions for a total weight saving of one pound. An unchanged single counterbalancer, gear-driven directly off the crank, is still mounted low down forward of the front cylinder block to iron out the vi- bration caused by the narrow cylinder angle, at the cost of a 3 bhp power loss in driving it. That V4 motor--still the only one on the Superbike grid--has been thoroughly reworked for season 2015.