Top speed is more limited by wind resistance than anything else. A taller geared bike just won't be in the power band at higher speeds, these engines continue to increase in power all the way to the limiter.
I run a 16 front and 44 rear. 100+ is easy to attain. I've never pushed it to the limiter in 5th, but I've gone to 110 mph at about 7k rpm.
