TOPIC:

Interested in some feedback on progressive springs. Would like to reduce the "dive".

They did wonders for my Honda CB900F. But I always thought it was odd that the KZ1300 takes the same Progressive springs even though it weighs a couple hundred pounds more.

Seven or eight years ago, I drilled out the damper rod, replaced the fork springs, installed a fork emulater ( controls oil flow up and down the fork to give better dampining ), removed the schrader valve from the fork top and replaced it with a screw mechanism to get preload onto the fork spring. Essentially converting the forks to more modern cartridge type.
If this is any use to you I can dig out some part numbers and names of suppliers.

I'd be very interested if you wouldn't mind hound dogging that info up and adding please and thanks Tackelhappy.

Me too.

Ok , here goes.
The two links below are a Canadian supplier, but the name Racetech is the important part. I bought mine from EPM Performance in New York in 2009. The don't even list the fork emulators on their website . Racetech would be the way to go.

fortnine.ca/en/race-tech-gold-valve-cartridge-fork-emulator

fortnine.ca/en/race-tech-fork-springs-80-kg-mm-frsps3234080
I did use these fork springs. They are not progressive type.
According to the letter from HP Performance - he states that the original springs are 590 mm long with a rate of 6.5 to 15.3 Kg/cm
To accommodate the emulators, the spring should be 530mm. So it is not possible to use the original spring if you want install the emulator.
The instruction sheet with the emulators said how many holes to drill in the dampining rod and what orientation.
If I remember right , the emulator sits on the rod , with the spring on top of that.
The tricky part is the length of the spacer on top of the spring, and lastly , a washer for the fork cap to push against.
The spacer length is arbitrary , depending on whether you want to have preload adjustability on the spring - hence the choice not to use a progressive spring as per original.
As you will see in the link for the emulator , the screw on the bottom is what determines the oil flow rate thru it's valve. The is some guess work here, some trial and error. Due to the placement location of the emulator being under the spring, if the flow rate is wrong, its a bit of a process to put the bike back on the centre stand , get the weight off the forks enough to get the fork caps off without damaging their very fine thread or yourself , remove spring , fish out emulator with a wire , adjust , and put it all back together - twice.

Something like as mentioned in this link is a much more professional look for a preload than mine is . Mine looks like it was made at the farm, as it mostly was.
motofaction.org/part-reviews/ttr400-prel...onda-cx500-400-064S/
I'm not suggesting this type will work -would have to check the inside diameter of the fork and thread type and pitch.
Let me know what else you might need. Actually , I did this in 2009, a lot could have changed for the better since then.