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YZ400F Stack opinion and tuning advice

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Hey guys,

I wanted to ask your opinion on a couple things regarding my 400f's fork tuning. I have been searching the site for some answers but can't seem to find too much about the 400s. I'm trying to understand more about my suspension and how to properly tune it. I think I understand some of the basic principles but am still lost on some. So here are my questions below.

1) Is there a site that describes the inner workings of these KYB forks? Or that describe fork/stack tuning? I've read the stickie in this section already.

2) I have the base valve out (that's for compression correct?), should I take the other out of the cartridge too? (different wording of this question: which one usually has a larger effect on the forks, the base valve or the valve inside the cartridge?)

3) Here is my stack below for the BV. I think it is stock.....? I'm 185 with gear, a C rider who does 50/50 between track and the woods, here in the midwest. I'm not balls-to-the-wall aggressive but not a slouch either. As far as fork behavior. I'm not bottoming out the forks but it is pretty harsh on big landings. A little more plushness would be great. In the woods it works pretty well but since I have been riding this for a few years, I've gotten used to it unfortunately. The springs are correct of my weight, according to the racetech site. I have changed the oil several times, to the correct level, and have just received a rebuild kit for them, which I'm be installing shortly. I cased a triple in November and broke one of the white tubes in the left fork, which is why I've decided to take this time to redo them. I've looked into the gold valve and such but it would end up costing about half the value of the bike, haha.

What changes can I make to this stack to help me achieve my goal? (and if possible, why?)

(eight) 24 - .10

(one) 22 - .13

(one) 20 - .13

(one) 18 - .13

(one) 16 - .13

(one) 14 - .13

(one) 13 - .13

(one) 12 - .13

(one) 11 - .13

(one) 18 - .50

Thanks in advance for any feedback.



Edited by Yz400Flyer

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If you want to take some of the sting out of the harshness try this with 110mm oil level.

(5) 24 - .10[/font]

20 - .13[/font]

18 - .13[/font]

16 - .13[/font]

14 - .13[/font]

11 - .13[/font]

18 - .50[/font]

But these have a ton of bleed at the mid-valve with zero support for the mid-valve shims. The shims got destroyed quickly. That makes the fork blow-through the first half of the travel which makes for a damping spike both at the base-valve stack and from the air-spring. They also have what we call a cylinder valve (CV) at the top of the cartridge. It was supposed to allow air/foamy oil a path out of the cartridge to make for more consistent damping. It worked too good dumping the damping...

The ABS kit above eliminates the CV. The stock bottoming system was harsh and unforgiving. The kit upgrades that too. You need to have someone install the kit that has some valving knowledge and shims though.

Edited by KTM-Lew

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Man I hate this boards software. I've tried three different browsers. Using Chrome for thsi post. Where the heck did all the font crap come from?

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