It's generally an accepted truth that the big four Japanese motorcycle manufacturers will find some way to incrementally improve the performance of their various 600cc sportbikes year-after-year. At some point, you may begin to wonder just how much more juice can be extracted from a relatively small displacement engine.

According to a recent test by, both the 2009 Yamaha R6 and the 2009 Honda CBR600RR are down a bit on the dyno compared to their 2008 siblings. Why? The Honda's issue may be related in part to U.S. noise regulations and the tricks that cycle manufacturers employ to get their screamers down to lawful decibel levels at their high-rpm power peaks.

For its part, Yamaha has tried hard to boost the weak mid-rpm power that the ultra-aggressive R6 has been saddled with the last few years, but that retuning may have yielded too high a penalty at higher revs. This small problem doesn't seem to be affecting Kawasaki, though, as Team Green was able to punch out an impressive 107.7 horsepower at 14,100 rpm from the '09 ZX-6R's 599cc powerplant, all the while remaining competitive in the mid-range.


Share This Photo X