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/128406
_2_0_0_6_Y<_o_rn_o_ho_Y._ZF_-_R6 _ appetite for revs. The nature of the track was perfectly suited to the R6 with rhythmically connected sweeping and smooth corners. There is one first-gear hairpin, but for the most part the corners are mediumspeed - second-, third- and fourth-gear corners. My first session out, I was just trying to learn the track and I totally forgot about the fly-by-wire throttle system, which I guess is a good thing. After I figured out where I was going and started to concentrate on what the engine was doing, I was very impressed by how linear and smooth the power of the bike is. The power is deceptive in a way, as there isn't really a big spike in the delivery anywhere, which is exactly what the engineers set out to achieve. The bike felt strong exiting the first-gear hairpin, but then again the tachometer was already singing at around 12,000 rpm. Without riding the bike on the street in normal conditions, it would be hard to These are the new throttle bodies with shower secondary injectors. The new engine is a rewer. No, make that a screamer. The already short-stroke engine is now even more oversquare with 67 x 42.5mm bore and stroke dimensions (compared to 65.5 x 44mm in '05), but that is only of the one elements that allow the motor to rev to over 17,500 rpm. Ultralight, larger titanium valves (27mm intake and 23mm exhaust) with chrome-nitride coating and aluminum valve retainers, 7-percent-lighter ultrashort skirted pistons (which are only 37.5mm in height) and a crankshaft with 26-percent less inertial mass (and smallerdiameter journals but larger crank pins) all contribute to allowing the engine to spin faster more qUickly. The included valve angle has been further reduced; the intake-valve angles are now only I 1.5 degrees from vertical (14 degrees in 'OS) and the exhaust's are now 12.25 degrees from vertical (14 degrees in '05). The compression ratio was raised (from 12.4: I in 'OS) to 12.8: I for 2006. 24 The new titanium valves, and lighter crank, rods and pistans help allow the new motar to spin beyond 17,500 rpm. Probably the most important news about the R6's new engine is the fuel-injection system, which now has secondary shower-type fuel injectors and ultrashort intake funnels for high-rpm throttle response and increased efficiency. More drastic, however, is the new MotoGP derived YCC-T (Yamaha Chip Controlled Throttle) electronic-throttle system, which eliminates the use of a throttle cable between the throttle and throttle valve. It is completely computer-controlled. Sound scary? It shouldn't, as it's the next big trend that probably will be seen on most sportbikes over the next few years. And it works, but more on that in a minute. The purpose of the YCC-T is to improve the manner in which the fuel/air mixture is delivered to the engine. The target was to help smooth out the torque curve and increase the amount of it in the midrange, and increase response time for improve acceleration. Think of it this way: On a traditionally "connected" throttle-cable setup, the rider NOVEMBER 30, 2005 • CYCLE NEWS will occasionally crack the throttle wide open very quickly, which in turn may deliver too much fuel and make combustion less efficient. What the YCC-T does is to gather all the data available to it, including air temperature, intake air pressure, atmospheric pressure, crank position, engine speed, throttle position, and so on and so forth, to determine the best possible throttle-valve (butterfly) openings. The information is then fed to the R6's new ECU (electronic control unit) - which has five times the computing power of the previous-generation bike. The ECU has two 32-bit processors (one just for the EFI) and then a 16-bit sub CPU as well. It then picks the best maps for the fuel delivery which includes determining if it should pick the throttle-valve-angle control map for first through third gears, or the other for fourth through sixth gears. All of this in an effort to put the power to the rear wheel as efficientlyas possibly. On the Losail track, it was qUickly apparent that the R6 has an insatiable comment on the torque output, and midrange output of the engine, but what I can tell you is that there sure isn't a lot of bottom end. (Hey, who needs it anyway?) This bike is all about keeping the engine above 12 grand. I must say that the fuel delivery (at least on the racetrack) is as smooth and responsive as anything I can remember riding from Yamaha in a long time. It reminded me of the RI two generations ago, which had the vacuum secondary-throttle butterflies and incredibly smooth and perfect carburetor-like delivery. One thing that is also instantly noticeable and welcome on the R6 is the new slipper clutch. In addition to the bike's new chassis attributes - which I'll get into in a minute - the slipper clutch helps make the bike super stable when getting the bike downshifted through the smoother and improved gearbox and set up for corners. Going down two gears for the first-gear, left-hand hairpin, the slipper clutch would just allow the rear end to step out gently,