rear shocker

[Metal Merv]

I am still bouncing like a pogo stick even though I have now got a zx10 spring fitted.can anybody tell me if I remove spring from shock,how much resistance should there be when pushing damper rod up and down.also if I adjust damper will while no spring off should the resistance increase.thanks peps.

[PaulSmith]

Bouncing around is not the spring, it is damping. I have not heard of anyone using the ZX10R suspension on a Fazer before, do you have a write up anywhere?

I did a write up on another forum about adjusting suspension that I have reposted below. Sorry it is so long but it was part of a long conversation. The actual process is easy. 

Mis-information regarding motorcycle suspension is legendary, the most fundamental issue is that suspension is not about comfort, it is about handling. It is just a pleasant coincidence that a good handling bike is usually much more comfortable then a bad handling one.

The purpose of suspension is to keep the wheels on the road. The reason that this is important is because you can not brake, accelerate or steer if your wheels are not on the road. Things trying to push your wheels off the road are bumps, imperfections, dips, potholes, braking, accelerating and cornering.

The wheels have a range of motion that they can travel through before the rest of the bike must move. The normal range (known as 'static sag') is 30/70 (or sometimes one third/two thirds). That means that when the bike (and its payload, ie you, your pillion and/or your luggage) are not doing anything else, the suspension is using 30% of its travel. This leaves the wheel up to 70% of its travel to move up if pushed by a bump, or 30% that it can move down to fill a hole. This adjustment is made with the spring preload. A heavy rider with a pillion will need a different amount of preload to get the same sag as a light solo rider. If the weight is too much for the spring, or the spring is too strong for the weight, or if the preload is not correctly set, then the sag will not be in the required range, meaning the wheel wont be able to move as far before the bike has to move. Despite what you will read elsewhere, preload doesn't do anything else except adjust the sag.

A spring is like a pendulum, once you get it moving, you need to apply a force to stop it again. When suspension moves, oil is forced through a valve which dampens the movement by resisting the flow of oil. Rebound and compression are one way valves so you can have different amounts of resistance when compressing the spring and when expanding (rebounding) the spring. Additional valves and bypasses can be added to control high and low speed behavior separately.

The amount of dampening you need is dependent on the weight on the bike and on how you ride. If you have too much, the spring can not return to its neutral position quickly enough to absorb the next shock, so the ride will feel harsh and get progressively harsher on rough roads. If you have too little, then the spring will continue to bounce for longer then is comfortable. This affects you for example when you brake into a corner (compressing the front spring). As you come off the brakes, the spring will extend making the forks longer and opening your turn, but without enough damping, they will contract again, shortening the forks and making the turn tighter, they will then extend again, and so on.

If you think this is a lot of work, it isn't. There is one simple objective step, setting the sag. All you need is are two friends and a tape measure. And there is one simple subjective step, setting the damping to suit your taste. That involves turning a knob and if you don't like the result, turning it back again.
If you want to call this rocket science, then it is the sort of rocket where you drop some 'Mentos' into a bottle of cola and run away laughing.

Whether you want to do this once every time you get a new bike or once every time you ride out is your choice. I choose to do it once every six months or so and then once before I go on a trip with my missus and/or luggage.

The process I use is pretty simple and works on the road and the track. There are others ways to do it but this works for me.
Rule 0. Set the Sag.
Rule 1. Stop when you cant tell the difference.
Rule 2. Write down your starting point.
Rule 3. Halve the remaining range.
Rule 4. If you don't like what is happening, go back to your starting point.
Rule 5. Same as rule 1.
Rule 6. Write down what you did.


Setting the Sag:
Nothing else will work right until this is set. And remember, close enough is good enough. If you have set it before (and remembered to write it down) then you already know the target height you are looking for, so it is just a case of checking you are there. If you don't know your target, look up the specs for the suspension travel of your bike. Your target is 30% of that range. For the SX it is 120mm front and 135mm rear giving targets of 36 and 40mm respectivly (remember near enough is good enough).   
This needs two mates to help so can be a nuisance to arrange, but if you group together, you can help each other. One thing to be aware of, you need to measure the actual movement of the bike, not the movement of the control as a) the control moves the bike and b) the control might be geared.

To set the front sag if you have a center stand, put the bike on it and get a mate to push the back of the bike down so the front wheel is off the ground. Measure from two fixed repeatable points (I suggest axle to dust seal) write this down as your MAX. If you don't have a centre stand, you and your mate can simply lift the front of the bike until the wheel is in the air and then measure the length. Now take the bike off its stand and sit in it. Get one friend to hold the bike stable so you can lift your feet onto the pegs, and get your other friend to measure the same length again. The difference between these two is your current sag. Adjust your preload up or down to get it closer to your target. Setting the rear sag is the same procedure but there is no easy place to measure. I would suggest you and one mate lift the back of the bike off the floor and get your other mate to measure from the axle to a point on the grab rail vertically above it. The reason to get your mate to do this is so they can measure exactly the same place when you are sitting on the bike with your other mate holding it stable.

Setting the damping:
Step 1. Pick a test route. It should include the type of roads you typically ride. There is no point in setting your suspension for a dirt track if you only ever ride on motorways and vice versa. I prefer a route in a figure eight so I can bail out early if I have fecked up.
Step 2. Ride the route a few times. This is because you will get used to it and come to anticipate the bumps and imperfections and this will change your sensitivity to them. You don't want to think an adjustment is better or worse just because you knew where the bump was and braced for it.
Step 3. Record your starting point. Count the clicks to max. Then count them back to your starting position. Then count the clicks to min and the clicks back to starting position. Doing both only takes slightly longer but protects you from failed adjusters that don't stop at the limit.
Step 4. Pick one adjuster and put if half way to the further limit. For example, if your rear rebound has twenty clicks and you are on seven, then 20 is further away then 0 and half way between 7 and 20 is 14. Ride your test route. The change is clearly better, clearly worse, or not noticeable.
   If it is better, then your starting position becomes your new limit. ie you are now looking between 7 and 20.
   If it is worse, then your current position becomes your new limit. ie you are now looking between 0 and 14.
   If the change isn't noticeable, you are done. Time to move on to the next control.
   If you don't like what is happening, put is back to the starting position and move on to the next control. You can always come back later if you want to.
 
The only difference between you doing this and Valentino Rossi doing this is that the Dr. is able to notice changes that you can't.
If you really want to be like the Dr., get a mate to make the adjustments and you tell him better/worse/didn't notice. He should send you out with no change a few times to check if an improvement is real or imagined.
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[Metal Merv]

hey paul thanks for info very handy.i put zx10 spring on because it was so soft when I press it down but not sitting on it.i hoped the spring would help.it did a small bit but not enough for me to ride at a good pace.i have wound rear screw up more today so will try it Saturday.i have set sag front and rear it was the first thing I did.as I said in my post my damper rod don't have much resistance with out spring on.i am thinking it works like a steering damper so the more you turn it up the more resistance you get.i always write down anything I do on forks or shocker.i think by what you have said and others that my shock may be shot.thanks.