There has been so much confusion and misinformation regarding the 2013 Kawasaki KX450F Kayaba PSF (Pneumatic Spring Fork), that we decided to corner one of the guys helped develop the fork in question. Dan Worley worked as a development technician for KYB for 11 years before moving on to start his own business earlier this year, SDi. He saw the PSF through it's early stages all the way to mass production and already has a few years of experience with what has become known as the "air fork." If anyone knows the proper way to adjust and monitor the PSF on the KX (and 2013 Honda CRF450F) it's Dan.

Proper Setup for the 2013 KX450F KYB PSF Fork - More Motocross Videos

Proper Setup for the PSF Made Easy

1. Know Your Gauge

a. Know how much pressure is lost from attaching your gauge and adapter setup.

b. To check this, attach your gauge and see what pressure is in the fork.

c. Loosen the gauge completely, and attach it again.

d. Notice how much the pressure changes from the first time you checked - that is how much pressure drop is from the gauge itself.

e. Know what pressure you like on your gauge. There are so many cheap gauges out there that have huge tolerances. If you like 33 psi on your gauge, remember that, and don’t worry if your buddy’s gauge says something different.

2. Check Your Pressure Every Morning

a. Check your pressure every morning before you ride! Your suspension will not work correctly if you don't!

3. Mid-ride Adjustments

a. When checking/adjusting pressure during the day, you must add or subtract from the pressure that the gauge reads then, NOT from your morning base setting.

b. As the fork gets warm, the pressure will increase.

Example: If you start at 35psi, and you want to go stiffer after the bike is warm then you should check the current pressure. If it is at 37psi, you must add 1psi PLUS the amount you lose from attaching your gauge (typically about 1psi; see section 1).

c. If you want to go softer, and your gauge loses 1 psi every time it is attached, you will only need to attach your gauge to go 1 psi softer (since you automatically lose 1psi when you attach your gauge).

d. Finally - Do no Panic if you started at 35 psi and it increases to 40 psi! This is most likely from the cartridge heating the air after riding and not having oil splashing around to cool it.

4. Adjusting The Air Pressure is a Huge Asset

a. It does more than act as a stiffer spring - remember it adds friction, which acts like low speed damping!

b. It is important to find your upper limit on air pressure and initial fork comfort, to much air can make initial movement harsh.

You must play with the balance between the compression clicker adjustment and air pressure.

-Dan Worley

Create New Tag

    12/4/2012 5:29 AM

    Someone needs to learn how to spell gauge correctly. 11 errors of the same word (from a quick skim), with weirdly, one instance of the correct spelling.

  • bayodome

    12/4/2012 10:37 AM

    Thanks for pointing that one out...fixed. When did you join the Grammar Police force?

  • Carlton_Fartman

    12/1/2012 6:32 PM

    Decent info, but it doesn't really cover my concerns:
    -How easy it to blow a seal and lose air?
    -What happens when it loses air?
    -How much will the suspension change if I don't check it throughout the day?

    My concern is that this will be a pain in the ass for a local racer. Between motos I scrape the mud and add gas to the tank, and let air out of the tires if the temps have gone up a lot througout the day. I don't change tires/gearing/mapping/etc to suit track conditions. Half the time I'm like "Shit! I forgot to put tearoffs on and I'm in staging!", and this procedure looks more time consuming that that...

  • filthyanimal

    12/1/2012 10:29 AM

    Hmmm... So, sounds like some "best guess" stuff... and learning to "feel" how the thing works--especially with the changing temp as the bike is ridden--is what it will really come down to. And, spring (air pressure) and compression damping aren't really independent...

    So, pick which part of the track...and at WHICH POINT (time) of the race you want the thing to work best?

    With mountainbike air forks/shocks, the suspension characteristics totally change as the things heats up. Also, trying to keep enough low speed damping so that the fork doesn't dive AND still having decent small bump compliance is nearly impossible (you kinda have to chose one or the other).

    It'll be interesting to see how they (air forks) work out. Currently, I think I'll go with something that I can set up accurately and that will remain quite consistent through out the day, regardless of friction and temp. When you think about how much difference a couple clicks on dampers make on the current stuff, it's huge, so I'm not sure that I want try to guess how much temperature and friction are actually going to affect the tune of the fork and then hope that I'm going out there with something I can trust... All for small weight advantage. Seems like there're better places to save some weight...

    That being said, I'm sure I'll be on a pair sooner then later... Are air shocks next? (Nitrogen?)

Show More Comment(s) / Leave a Comment