I bought a GP Suspension 25 mm cartridge kit and a revalved and resprung rear shock for my 2004 zx10 some time ago but only recently got to test them out at Philip island race track down here in melbourne, Australia. T
he sags have been set up with 5 turns of preload on the front and 32mm rear as they reccomended and I had some good tyres on them as well. dunlop gp racer on the rear and an Alfa 11 on the front.
Anyways I had a few questions about setting the bike up.
I started off with 12 clicks of compression and rebound on the front forks and found that the back was going light and moving around going into turn 4 and after 9 which are very hard braking areas. I have excellent brakes on this bike and would like to use more brakes if the back was a bit more stable. I finally settled on 8 clicks of compression which made the front a bit better under brakes but still moving around
I currently have a zip tie on the front and it shows that I still have 30 mm of fork travel left. I am wondering if this is alright as ideally I would like to use the whole travel. Topped out the front suspension travel measures at 137mm. I have heard you can remove things that can give you full travel. Is this ideal? how much travel are you guys using??
Secondly there is 140 mm of air gap from the top of the fork with the spring out in it. Is this the right level or should I change it to make it a bit better under brakes?
Thirdly the bike feels very heavy to steer at high speeds. do you guys find this?? I have a ride hieght nut that gp suspension sent me as well and I will be installing it soon and would like to know if I take the spacer thats in there out first or just add the nut to the spacer that is in there already. It measures at about 3mm.
does dropping the forks have the same effect as raising the rear. I am asking because I dropped the forks by 10 mm all up and it caused the bike to tuck so I put them back to 5 mm. Would raising the back end cause it to move around a bit more??
Finally the rear shock feels good over small bumps but gets harsh over largish bumps. I did a bit of looking into it and found that the standard swingarm linkage angle causes it to get progressive and harsher as it moves up. I will be putting in a 05zx6 rocker to see how this goes.
I'll take a stab at it for you... (Disclaimer: I am not in anyway a suspension guy, just a avid track day junkie that does my own wrenching that reads alot about this kinda stuff....)
Are you a trail braker or do you complete all of your braking before you turn in?
If you are a trail braker you need to have that travel available to you for error correction or bumps in the corners as you are going into the corner with the front loaded. (Read; do not bottom out and tuck) If you are a straight breaker you are unloading the front before you enter so you can use all of the stroke during hard breaking. The decision here is yours.
..that being said, you did set your front sag so that approximately 80mm of lower fork tube is showing from the wiper to the bottom axle bracket and the springs are set for your weight, like a 1.00 or a .95 Kg/mm (Stock is 1.00) How much do you weigh, if you are 170+ gear one of these two will work. If you want to use more stroke decrease the compression damping a little if your sag is correct....or alter the shim stack...
The air gap / oil level should be at least what Kawasaki recommends. Since you are not using the full stroke the air spring effect is not really coming into play. Leave as a stock value. What weight fork oil 5, 7.5 or 10?
Direction changing...where is the rear axle in relation to the indicators in the swingarm (Read, are you running a longer or shorter wheelbase than stock because you altered your gearing) Longer wheelbase = Stable, Slower reacting. Shorter wheelbase = Quicker, Faster reacting. Now, that being said are you talking changing direction during a quick chicane or are you talking sweepers?? If it is a chicane, look to speed up the rebound to help the front forks extend to aid in throwing it over to the other side, if it is a sweeper consider the wheelbase or trail length you may currently have. Since you did not mention adjustable triples, your only option is to play with fork tube heights and rear ride heights. The rear ride height has less effect on the trail than moving the forks, more effect on the swingarm angle and corner exit. Make adjustments at least 2-4mm at a time, one thing at a time until you feel a difference than move to a lesser adjustment as you get closer. 1mm or even 1/2mm adjustments are very hard to even notice and just take too much time if you are trying to sort something out. If the bike falls into a corner and you find it is understeering to the apex causing you to add throttle so as to not run into the turtle raise the front of the bike with physical movement of the tubes or add pre-load. If you find that you are steering the bike too much and have to hold it to a line, lower the front slightly until it feels good to you.
If you split the bike in two, i.e. the front forks and related stuff for entering the corner, with the rear stuff for exiting the corner you can stay less confused. Yes, there is some cross over and bad rear set-up effects steering on corner exit, but because you are driving off of the corner you know you should be addressing the rear not the front. Subsequently as you are entering the corner the effect of the handling is due to compression trail, weight transfer, springs, oil, compression damping e.t.c....
The rear linkage, harshness.. How much did you change the pre-load collar on the shock, stock it is stupid loaded, you have to unwind it lots to get a decent sag setting, again your weight is needed to get the sag to 20-30mm as you sit on it. Adjusting the rear height would be a adjustment for getting the best swingarm and for corner grip and drive. Since you cannot raise the front swingarm pivot, you adjust it at the shock mounts to alter the angle. Yes, if you raise the rear it alters the trail, but such a small amount it is like those 1/2-1mm adjustments that you are hard pressed to feel, therefore it is more of a swingarm angle adjustment.
...Oh, and one more thing really pay attention to your pressurized wheel circumference if you change tire size / brands e.t.c, because if you go bigger or smaller depending on the rubber it will change you geometry and will provide you with a different feel and you will have to adjust the bike again.
I hope it all made sense and I did not confuse you...