KYB PSF1 in a YZ?

wst260
Posts
22
Joined
5/2/2020
Location
AU
1/5/2021 7:15pm
Hi all,

has anyone experimented with putting a set of PSF1’s stock or revalved in a 2014+ YZ450?

Curious to hear the positives and negatives of anyone that’s done the swap

Cheers
1
|
m21racing
Posts
634
Joined
7/19/2016
Location
Reno, NV US
1/6/2021 7:25am
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav forks. We've used them on 16 kx450, 17 yz450, and on kx250 2t bikes.
I like the fork. Once you get it set up to your liking, its as good as anything. I used the skf hd 48k seals, and factory bushings on the dlc coated forks.
1
Rider 5280
Posts
2006
Joined
11/9/2011
Location
Denver Metro, CO US
1/6/2021 9:16am Edited Date/Time 1/6/2021 4:12pm
I personally feel air forks get a maaaajorly bad rap.

I've got 2 sets of KYB PSF1 A-kit air forks (1 set on CRF, 1 set on YZF) + 1 set KYB A-kit spring forks (on YZF). Both are amazing, but I have to say I **really** like the adjustability of the PSF1s. A LOT.

I recently spoke at length with an ex KYB Factory Tech who worked with KRoc and ETomac on air forks when they were under serious development and he said they got the air fork to perform better than the A-kit spring forks. There are a number of reasons that air forks went away on production bikes, I get it, I also deal with R&D vs. production decisions, but I am here to tell you that my Vet B/C opinion is that A-kit air forks are AWESOME - their bottoming resistance is unbelievable and their adjustability is very useful and frankly, fun. And the A-kit spring forks are awesome, too.

I'd reach out to Klint Stapes. He has some "special sauce" for setting up air forks. He learned a lot in his tenure at ENZO and KYB as well as a career as a pro rider. He can help you with this decision, for sure, and revalve air forks to your liking. Here's his contact info:
Stapes Suspension @ 951-833-4043
https://www.instagram.com/stapes_suspension/


2
coastie44
Posts
545
Joined
1/19/2013
Location
NorCal, CA US
1/9/2021 8:38am Edited Date/Time 1/9/2021 8:46am
+1 on the PSF1 air forks as working really, really well. I loved the feel of mine on my KX450F after a revalve. What I didn’t like is that they changed throughout the day. In NorCal we would often have cool mornings and warm days and the forks would work awesome early, and then get harsh as it warmed up.

I eventually converted them to spring just to eliminate that. I’m not a racer and just a vet weekend warrior and I didn’t like dicking around all the time with the air pressures to keep them feeling good.
1
Rider 5280
Posts
2006
Joined
11/9/2011
Location
Denver Metro, CO US
1/12/2021 1:49pm Edited Date/Time 1/16/2021 11:08am
Along-the-lines of Coastie44's concerns, I just bought this $170 automatic fork bleeder/pressure product (for spring forks) as a starting point to explore its ability to bleed off pressure in excess of a specified set point like 34 psi for PSF1 A-kit air forks with the incorporation of a checkvalve similar to that shown in the second link.

https://www.airprofork.com/snowbikes

https://www.pegasusautoracing.com/productselection.asp?Product=3336&utm…

(correct - this is NOT its typical application and it needs some modding)

The Shop

cdoggy81
Posts
1305
Joined
1/1/2018
Location
St. Petersburg, FL US
1/13/2021 5:55pm
Nice & I really like those Pegasus air caps!
mxryan25
Posts
175
Joined
11/27/2018
Location
Dayton, OH US
1/14/2021 8:48pm
Rider 5280 wrote:
Along-the-lines of Coastie44's concerns, I just bought this $170 automatic fork bleeder/pressure product (for spring forks) as a starting point to explore its ability to bleed...
Along-the-lines of Coastie44's concerns, I just bought this $170 automatic fork bleeder/pressure product (for spring forks) as a starting point to explore its ability to bleed off pressure in excess of a specified set point like 34 psi for PSF1 A-kit air forks with the incorporation of a checkvalve similar to that shown in the second link.

https://www.airprofork.com/snowbikes

https://www.pegasusautoracing.com/productselection.asp?Product=3336&utm…

(correct - this is NOT its typical application and it needs some modding)
Correct me if I’m wrong but either of these won’t work, when your fork compresses the air chamber gets smaller causing the pressure to go up this is what gives the air spring it’s progressiveness. In order for a bleeder to work it would have to know to bleed at a certain set point, and only when the fork is fully extended.
Rider 5280
Posts
2006
Joined
11/9/2011
Location
Denver Metro, CO US
1/14/2021 9:22pm Edited Date/Time 1/14/2021 9:53pm
I reread my post above - very poorly written. I just revised it for clarity. Sorry for the confusion.

Recap:
I am building a system where I manually bring into play a checkvalve (that cracks at ~ 34 psi) when a thumb-operated (button) valve opens the pathway to the pressure in the PSF1 main chambers when the forks are uncompressed (over jumps, during wheelies, etc.). I bleed off the excess pressure (anything in excess of ~ 34 psi) as I feel the fork getting stiffer in a moto session.
1
cdoggy81
Posts
1305
Joined
1/1/2018
Location
St. Petersburg, FL US
1/14/2021 9:43pm
Ahhhhhh, makes sense to me now 👍🏻
MxGringo
Posts
4
Joined
1/25/2019
Location
SE
2/2/2021 10:52am
m21racing wrote:
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav...
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav forks. We've used them on 16 kx450, 17 yz450, and on kx250 2t bikes.
I like the fork. Once you get it set up to your liking, its as good as anything. I used the skf hd 48k seals, and factory bushings on the dlc coated forks.
1. Did you use the psf1 of kxf or crf?
2. Do the yz - 17 caliper fit the kxf fork, or do you need a 270mm brake disc adapter for the kxf
3.how muck did you lower the yzf-17?

I'm thinking of putting a set of kxf psf1 on my yz450f - 18
cdoggy81
Posts
1305
Joined
1/1/2018
Location
St. Petersburg, FL US
2/2/2021 3:22pm
I think you need to swap triples & lugs to make the kx work on the yz.
m21racing
Posts
634
Joined
7/19/2016
Location
Reno, NV US
2/2/2021 4:20pm
m21racing wrote:
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav...
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav forks. We've used them on 16 kx450, 17 yz450, and on kx250 2t bikes.
I like the fork. Once you get it set up to your liking, its as good as anything. I used the skf hd 48k seals, and factory bushings on the dlc coated forks.
MxGringo wrote:
1. Did you use the psf1 of kxf or crf? 2. Do the yz - 17 caliper fit the kxf fork, or do you need a...
1. Did you use the psf1 of kxf or crf?
2. Do the yz - 17 caliper fit the kxf fork, or do you need a 270mm brake disc adapter for the kxf
3.how muck did you lower the yzf-17?

I'm thinking of putting a set of kxf psf1 on my yz450f - 18
We straight swapped a set of psf kx forks onto a 16kx450.
The yz had modded kit style, and shock was 5mm lower. You should be able to use the kx on a yz, but lugs obviously different so that will be something to consider. We took brakes, wheel, etc and made it work. Had a few bikes. Trees shouldn't be an issue, but I would look at offset that psf kit uses when they fit them to other makes. Did well at hangtown nat in 14 with slightly modded fork on 14 kx450. I do like those forks, and besides the aer, it's best imo.
cdoggy81
Posts
1305
Joined
1/1/2018
Location
St. Petersburg, FL US
2/2/2021 5:47pm
What did you do for the valving for them? From what I’ve seen & heard the 3 port pistons work better over the older 2 port (which I can change out) but the rebound setting must be changed as well as the MSV spec but I’m not sure where to even begin with that stuff on my particular set...
MxGringo
Posts
4
Joined
1/25/2019
Location
SE
2/3/2021 6:15am
m21racing wrote:
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav...
You may have to lower the rear shock to balance the chassis with the psf fork. To this day, that is one of my guy's fav forks. We've used them on 16 kx450, 17 yz450, and on kx250 2t bikes.
I like the fork. Once you get it set up to your liking, its as good as anything. I used the skf hd 48k seals, and factory bushings on the dlc coated forks.
MxGringo wrote:
1. Did you use the psf1 of kxf or crf? 2. Do the yz - 17 caliper fit the kxf fork, or do you need a...
1. Did you use the psf1 of kxf or crf?
2. Do the yz - 17 caliper fit the kxf fork, or do you need a 270mm brake disc adapter for the kxf
3.how muck did you lower the yzf-17?

I'm thinking of putting a set of kxf psf1 on my yz450f - 18
m21racing wrote:
We straight swapped a set of psf kx forks onto a 16kx450. The yz had modded kit style, and shock was 5mm lower. You should be...
We straight swapped a set of psf kx forks onto a 16kx450.
The yz had modded kit style, and shock was 5mm lower. You should be able to use the kx on a yz, but lugs obviously different so that will be something to consider. We took brakes, wheel, etc and made it work. Had a few bikes. Trees shouldn't be an issue, but I would look at offset that psf kit uses when they fit them to other makes. Did well at hangtown nat in 14 with slightly modded fork on 14 kx450. I do like those forks, and besides the aer, it's best imo.
Yes the psf1 forks fit in the triple clamps on the y450f-18.
Im thinking I could use an brake disc adapter/hanger 270mm from a kx/rmz, and then the yz caliper would work.
And if I use the 20/25 mm axel from the yz 2t with a sleeve the yzf wheel should also work.
Please correct me if I'm wrong

Post a reply to: KYB PSF1 in a YZ?

The Latest