89 kdx 42. springs, still soft

[bill kdx nj]

89 kdx with new 42. springs and it still feels like the front of the bike sags. hitting logs and trees roots along the trail is hard pounding. I got 4 clicks out on the forks. still have stock aluminum preload spacers. please help

 

[glad2ride]

What amount of preload are you using?

What is your weight in full riding gear, including any tools and water?

 

[bill kdx nj]

170 total weight
I dont know how much preload I have, but when I had the forks serviced I had softer springs in. with the stiffer springs does the fork oil need to be adjusted along with the preload?

 

[dirt bike dave]

At your weight, the 0.42 springs should be more than stiff enough.

Raising the fork oil level will greatly improve bottoming resistance and stiffness as the fork nears bottoming. To measure, take the springs out and bottom the forks. See how high the oil level is from the top of the tube. I think you can raise it as high as 4". If your level is way to low (6" or more from the top with forks compressed), raise it to 4.5" or 5" for starters. A .5" change will make a noticeable difference in bottoming resistance and the last 2" or so of fork travel.

However, the classic problem with the old KDX forks is too much high speed damping. Basically, the fork does not move rapidly enough on rocks and roots even with the wimpy stock springs, but its still way too soft on jumps. It more or less does not move enough on rocks and roots, so instead of bottoming, you might be locking up. If your oil level is already high, you might have a damping problem.

Race Tech cartridge fork emulators will work wonders on your '89 KDX fork, and allow the fork to respond and use all its travel on rocks and roots. If you ride lots of rocks and roots, the emulators are a huge improvement.

 

[glad2ride]

The stock spacers are steel.

Have you read any on setting preload?

What about setting the oil level? Are you familiar with that?

The stock springs are .30, so if you had those, then I would guess the forks were butter smooth over roots and rocks.

Which weight oil are you using? Is it fresh oil? How long was it since you last changed it, if you did just change it?

I would want to focus on:

oil freshness
oil level
oil weight
amount of preload

You may also want to go out more on the compression adjuster.