It sounds to me like you are dancing around the problem - and we don't even know what that is yet. Since you are playing around with spacers, you need to measure the sag of the bike and do the whole shebang - whether you buy a new spring or not. Its best to do a run of the procedure below with your current springs and spacer, and then adjust from there. You cannot correct all of the problems by increasing or decreasing the spacer - the fork spring has to be the right strength for your approximate weight. Once you get the sag right, you can move on to the proper weight oil. This is the procedure as I understand it.
First you measure the length of the forks from the triple clamp to the top of the dust seal with the bike on the center stand and no weight on the bike's forks. (Mine were 121 to 124* mm). Then you measure the sag of the bike with no rider by pulling up on the handle bars an inch or so, and releasing. Measure. Repeat only this time push down and release. I did each one three times, then averaged them and again averaged the pulling up with the pushing down. This procedure is necessary because of fork seal stiction - which will be different for unweighting and pushing down. I did this trial because I wanted to see how much sag the bike alone had, but you can skip this step. However, accuracy will improve with doing so I think this step is good practice and gives you some good info.
Now do the same with a rider in full gear - pull up, release and measure, push down and release and measure. I did this while balancing on tippy toes only for balance. (My wife pushed down on the bars, released, then measured. I lifted, released, and she measured. It is helpful for all of this to have a helper measuring or use one of those expensive gadgets that allow you to do it alone. Now average each run of 3 the same as before.
Take the Full extension - avg sag with bike & rider. I had called RaceTech and they sold me a new spring with the gold valves based on my weight with all gear. My numbers were 124 mm (total extension) - 72 (Sag with rider and gear) = 49 mm Total average sag. Now a sag of 36 to 40 mm puts you right in the middle of the forks range. This is optimal. So I wanted 11 mm LESS sag. With my spring, 1 mm of more height translated to a spacer of 1.2mm, thus 11 x 1.2 = 13 mm more spacer to put the required preload on the spring. When I added this roughly half inch to the preload (I used a piece of PVC 1 1/4" plumbing tailpiece per dduelin's help), I ended up with an average total sag of 37.58333** mm. I was aiming for somewhere in the 36 to 40 mm range and I hit the nail on the head.
Yes this is a lot of work, and you will do all of this with the original springs (or your new ones) with your stock spacer. Adjust the spacer length and do it again. This time all you need to do is pull the fork cap, pull the spacer out, change its length as necessary, then check the oil level and reassemble the cap and measure it all again. If you cannot get in the proper range with the original springs, you will need new ones and then have to do all this a second time.
*there is a range here because my wife measured the first time and I think her accuracy improved as we progressed with this chore.
Note 1: I call "sag with bike and rider" the measurement from the fixed lower triple clamp to the top of the dust seal. You can make a mark on the lower fork - but any two convenient fixed points will work.
** Lets be serious here for a second. This is what my calculator said. I think our accuracy is +/- a couple of mm.
Note 2: My numbers varied as much as 8 mm in any one run of 3 measurements, they were usually within 3 mm of each other.
First you measure the length of the forks from the triple clamp to the top of the dust seal with the bike on the center stand and no weight on the bike's forks. (Mine were 121 to 124* mm). Then you measure the sag of the bike with no rider by pulling up on the handle bars an inch or so, and releasing. Measure. Repeat only this time push down and release. I did each one three times, then averaged them and again averaged the pulling up with the pushing down. This procedure is necessary because of fork seal stiction - which will be different for unweighting and pushing down. I did this trial because I wanted to see how much sag the bike alone had, but you can skip this step. However, accuracy will improve with doing so I think this step is good practice and gives you some good info.
Now do the same with a rider in full gear - pull up, release and measure, push down and release and measure. I did this while balancing on tippy toes only for balance. (My wife pushed down on the bars, released, then measured. I lifted, released, and she measured. It is helpful for all of this to have a helper measuring or use one of those expensive gadgets that allow you to do it alone. Now average each run of 3 the same as before.
Take the Full extension - avg sag with bike & rider. I had called RaceTech and they sold me a new spring with the gold valves based on my weight with all gear. My numbers were 124 mm (total extension) - 72 (Sag with rider and gear) = 49 mm Total average sag. Now a sag of 36 to 40 mm puts you right in the middle of the forks range. This is optimal. So I wanted 11 mm LESS sag. With my spring, 1 mm of more height translated to a spacer of 1.2mm, thus 11 x 1.2 = 13 mm more spacer to put the required preload on the spring. When I added this roughly half inch to the preload (I used a piece of PVC 1 1/4" plumbing tailpiece per dduelin's help), I ended up with an average total sag of 37.58333** mm. I was aiming for somewhere in the 36 to 40 mm range and I hit the nail on the head.
Yes this is a lot of work, and you will do all of this with the original springs (or your new ones) with your stock spacer. Adjust the spacer length and do it again. This time all you need to do is pull the fork cap, pull the spacer out, change its length as necessary, then check the oil level and reassemble the cap and measure it all again. If you cannot get in the proper range with the original springs, you will need new ones and then have to do all this a second time.
*there is a range here because my wife measured the first time and I think her accuracy improved as we progressed with this chore.
Note 1: I call "sag with bike and rider" the measurement from the fixed lower triple clamp to the top of the dust seal. You can make a mark on the lower fork - but any two convenient fixed points will work.
** Lets be serious here for a second. This is what my calculator said. I think our accuracy is +/- a couple of mm.
Note 2: My numbers varied as much as 8 mm in any one run of 3 measurements, they were usually within 3 mm of each other.
