Both have minimal fairings and are less comfortable than the '05 ZZR600. And the rider makes all the difference anyway: my friend Tom used to SPANK guys on R1's, 954's and Ducatis with his
stock '93 EX500.
I've ridden an R6 and it was indeed fast (and indeed uncomfortable) and the first thought that came to mind when I sat on a 636 was "So Kawasaki's making an R6 now; glad we got Lisa (my wife) the last of the comfortable ZX6R's."
The interesting things to me about these bikes is their approach at getting high hp numbers. The Kawasaki uses tall cams and big valve lift, which means they must also use stronger valve springs, which in turn necessitates shorter valve-adjustment intervals. The valves must be adjusted every 7500 miles on my '02 ZX9R and my wife's '02 ZX6R, but perhaps they've found a new magic material to reinforce the valve seats to lengthen the intervals between valve adjustments on the 636/ZX6RR.
Now Yamaha uses a different approach. Instead of using the extreme-lift cams and stiff valve springs, they get the high hp numbers with the 5-valve engine. They get good flow with 3 intake valves and easier cams, which also means softer valve springs. Easier cams and easier valve springs mean less mechanical friction and wear. The only real downside is that you've got 20 valve clearances to inspect instead of 16, but if you only have to inspect them half as often (say every 16,000 miles or more)...you do the math.
I really like the Yamaha approach and almost got an FZ1 instead of my current ZX9R, but the one thing Yamaha does that I don't like is boring the cylinders directly into the upper crankcase. They save lots of money in production and a little weight, but the end result is that you cannot simply bore or replace your cylinder block at your neighborhood machinist. You must find a specialized place (like Erion Racing in Torrance, CA) to do it and they charge almost as much as an entire new crankcase set. And if you want to simply replace the cylinders of these engines, you must replace the entire crankcase, because they are drilled as sets at the factories. So you're basically replacing the entire engine.
If you are fortunate enough to simply trade-in for a new bike every 2 or 3 years and don't ride too many miles, maybe this doesn't matter to you. But if you expect to get 100,000 miles out of an engine...
Blah-blah-blah...I've rambled enough. Either bike would be fast enough. Arguably too fast for public roads. Good luck.
-Calamari Chris in Carlsbad, CA
http://www.chrisandlisachan.com/superhawk.htm
if I get the bike. Also, I'll be checking with my insurance company to see how bad the damage will be over my 500R before I sell my bike and buy a new one.
