By Alex Edge
According to a report in a recent issue of British weekly MCN, Yamaha plans to continue the trend of using MotoGP-derived technology in their production sportbikes. The R6 was the beneficiary this year (mainly with its drive-by-wire throttle system, developed on the YZR-M1), but rumor has it next year's R1 will receive an even greater infusion of new design ideas that the company has tested in the world's premiere racing series.
The new R1 will almost certainly feature a developement of the same drive-by-wire throttle system used on the R6; in addition, it is rumored that Yamaha will be making some changes to boost midrange power without compromising peak power production. According to MCN, the company recently filed a set of patent applications which show technology that may show up in the 2007 R1: a set of variable-length velocity stacks (like those on the limited-production MV Agusta F4 Tamburini), as well as a variable valve timing and lift system.
Using either or both of these systems could help the Yamaha engineers develop a motor with much greater midrange power than the current model. Different length velocity stacks provide optimum power at different RPM; therefore, variable length stacks allow a smoother, broader spread of power. For more information on the advantages of variable valve timing and lift, see my article from February titled 'The Sportbike Engine of the Future: Camshaft Design'.
Another rumor is that Yamaha plans to abandon the current R1's 5-valve cylinder head for a more common 4-valve setup. This is another result of MotoGP testing and racing - apparently, Yamaha tested 4- and 5-valve YZR-M1s back-to-back last year, and found the 4-valve making smoother power and more midrange.