Kawasaki ZX or GP?

[motisbetter]

Whats the differences between the two different lines? For example, what is the difference between a ZX-6R and a 650R? I know the engine displacement is different, but what else?

http://en.wikipedia.org/wiki/Kawasaki_Ninja

[YZF750R]

One is a race inspired sport bike, while the other is a sport touring bike.

Sport bike has a more rigid riding position and more HP while Sport Tourer has a more upright riding position and less performance. Less cylinders = less performance

[wordnerd27x]

Not sure what the GP is. But the 650 displacement Kawi that I'm aware of has a twin cylinder, inline engine. The 600's have a 4 cylinder, inline engine.

Typically, more cylinders for a given displacement results in higher rpm and peak horsepower. This is for various mechanical reasons. Fewer cylinders for the same diplacement results in lower peak power but higher low end torque (and overall smaller engine weight, all else equal).

A V configuration typically results in higher torque than a similar inline engine, but greater weight and vibration.

Today's inline 4's are the kings of street bike power/weight ratio.

Large bore twins are the torque kings.

Small displacement inline twins are a compromise for good fuel economy, reasonable power, and light weight, while maintaining enough torque off the line. They are not gonna give you significanly more low end torque than the 600's in that package, but will cost less and save you a lot of money on insurance. They might even increase your lifespan.
But they won't make you grin the same way as a 600 inline 4 when it hits its powerband.

[PonyDriver]

The ZX6R with its inline four engine produces more HP and is designed as a race bike where the 650R with it's parallel twin engine is not as fast and the rider sits more upright. More like a beginner sport/touring bike. Your insurance will be alot less with the 650R also.

I ride a 2007 Ninja ZX6R