I have a 2007 klx 250 and I think that the oil level is 101mm down, but what is the minimum level? Playing with the fine tuning is what I'm up to.

 

I have no idea how low you can go but I would think that as long as the cartridge doesn't cavitate it should be ok. Less oil should reduce the cumulative effect of the air volume adding spring rate so the only way to see what it does would be to test and alter volume. I'm happy with 110mm on my 12.

 

You went up which would be less air and stiffen the action as the fork compressed. I'm looking to sit further into the travel in hopes of lowering the front end a little. I lowered the back end, slid the forks up in the triple clamps, all because I'm a little vertically challenged. The changes have relaxed the head angle and I'd like it a little steeper to make it turn faster.
I'll start with 10mm lower and see what happens.

 

Oil height won't affect ride height

 

Here's my thinking. The air acts like a spring, the larger the volume, the softer the initial part of the travel, so when bouncing down the trail the fork will be compressed more than if there was less volume.
So is the active ride height just determined by the spring?
If I want to lower the ride height, I would need to change what ever stops the fork from extending and get a shorter spring? I'm looking for maybe an inch.

 

The air in the space determined by the oil level usually only comes into play as you approach full stroke...and definitely so in the KYB fork on your bike. Riders usually play with oil level to influence how the fork bottoms out...or at least approaching bottom out. Your initial travel and plushness is controlled by the springs and the damping circuits...usually mostly low speed compression damping.

 

110mm is about 6mm lower than the stock setting of 104 and 20mm lower then what Racetech suggested. Remember that you are measuring the air volume at full compression so a larger # equals a larger volume.
Sag settings are based on spring rate and preload-air volume won't really have any effect on sag. Read up on how to set sag and that will show you if a spring change is needed. http://web.archive.org/web/201309070...on.com/kb1.htm

 

Oops, got that backwards on the oil level.
Read the link, thanks. Race tech says that I should use a .392 and stock is .38. I'm using the 2007 KLX300 data, they don't list a 250 for that year. If I stick with the stock spring, but shorten the fork, will that be like adding a little preload on the spring and affect the initial part of the travel? Also affecting my sag height? I checked the sag and it is very close to what is recommended with everything stock. I never bottom the front end.

 

Maybe instead of messing with your forks, just buy a cheap used KLX300 seat off eBay (I got one for like $40 or something), and shave it down?

The seat is exactly identical to our 06-07 KLX250S as far as fit goes.

 

I have thought of doing the seat mod, but I like the seat to peg relationship when I'm seated I would like to keep that for when I do road rides. I stand a lot when off road so it wouldn't matter then. Maybe I need two seats. That being said, I like to mess with stuff and in doing so, learning what makes things work....or not. I think that I will continue my fork mod quest. Now I need to find out which piece stops the fork from extending. It looks to be one of the bushings.