About adjusting rear ride height.You can do this by the tie-rod in the shock linkage. This is useful when you switch to 17-inch low profile radial tires. (Otherwise you will need a longer shock to keep chassis attitude at desirable level.)
Essentially, you want the bike to steer as fast as possible while maintaining stability and not dragging. Impossible ? Well, you have to try different settings and find out *your * best setting.
I personaly think you can tip the bike forward safely, since GPz s have fairly lazy steering geometry, especially turbos.Maybe some people like it the way it is now(slow and vague, kind of easy to live with), I want to make it steer faster. To do this properly, you need to understand some basics about motorcycle's steering geometry. I will cover this separately. FORKS, YESTERDAY
Now , we get to the interesting point. You set up your bike, take it for a test ride, change settings accordingly. Use manufacture's standard setting as a starting point. Do one at a time, starting from rebound damping ,then compression damping, .keep the record what setting change made what difference... That what books tell us...
Well,...there's no external adjusters on stock GPz forks. How do you change settings? Or, where do you start if you adopet different forks?
Stock GPz forks(and all Kz's) are "damper-rod style". I'm not going to explain how the damper-rod style forks work here, as it takes too much words. Instead, take a look at the Genuine Service Manual page 210,211. That explains all.
Read the manual ? Ok, now you know that there are two ways to change damping force of damper-rod style forks. One, by changing the size of orifices. Two, by changing oil viscosity. If you want more damping force, you make those orifice diameter smaller , or use higher viscosity number oil. If you want less, do opposite way.
"Well, I just throw a set of progressive springs and pour heavier oil for more damping. ('cause that's easier ) " This is probably the easiest "up gread" suggestion you'd hear all the time, while in reality it hardly improve anything,...And here's why;
1) The way damper-rod forks work is just by shoving oil through a hole(orifice), and that's a *verocity-sensitive* function, it doesn't care "where " it is in the stroke. All it cares is "how fast" it's being stroked. It is called verocity-squared damping: move it twice as fast, the damping is four times as much. See what's wrong here? The damping you get from this system is just too progressive. Not enough low-speed compression damping, too much of high-speed damping. (high/low speed means "suspension's" stroke speed, not necessarily means vehichle's speed) And this is why your front end dive too quickly under braking(not enough low speed damping) yet kicks off when you hit the bump.(way too much high speed damping) This means you CAN' T determine damping setting by pushing the front end down while sitting on a bike. 'Cause you can never push the bars that fast.
2) The big problem (with damper-rod forks) on rebound is cavitation. Meaning they don't refill chamber properly. The smaller the orifices is, or the thicker the oil is, the bigger the problem is. 20w fork oil is pretty much useless. 15w is as high viscosity as I'd ever use. Also heavier oil is less stable, which cause "fading."
I guess some of you already figured out, "progressive" spring is an attempt to cover up the problem of poorly designed damper. It may work, in a limited way. But five out of ten times, it doesn't. The real problem is, most people do this kind of work without thinking. Believing that just because somebody says that improves your bike's steering..
Fundamentally, what you need is a spring rate that's right for appication, and a particular damping curve for that. If you can create that , it will work just as well as anything in the world. Unfortunately, damper-rod style does not offer this adjustment.
To create that right damping, there's Cartridge Emulator kit, Or, ultimately, you can switch to cartridge forks.