2021 KTM 450 Fork Mod Experience

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7/31/2021 9:11 AM

Hello All,
I picked up a 21 450 SX-F FE this year. Overall, it’s the best bike I’ve ever ridden, stock or modified. The only fly in the ointment for me is the stock fork setup. They aren’t terrible, and are the best air forks I’ve ridden. That said, they do exhibit two air fork hallmarks based on my experience-harshness on small chop and slap down or flat landings, and blowing through the stroke on big hits.

I’m going to ride as-is through this season, then modify them this winter when they’ll need an oil change/rebuild anyway.

Cone Valves/other A Kit are out of my price range. As a result, I see three options:

-revalve/other mods, keep the air
-revalve/spring conversion
-KYB conversion (possibly out of my price range as well).

My guess is that I’ll end up going the spring conversion route. That said, the idea of the single spring just bugs me. Not sure why, just seems like a Mickey Mouse arrangement to me.

I know there’s a couple other options (Del Saggio, MX-Tech) out there as well, but it seems like those get close to the KYB cost.

I’d like to spend the least amount possible for the best value-ie if spending a couple hundred more gets significantly better performance, I’d go that route.

So for those who have done these, what are your thoughts? For reference, I am an over-40 B/C level rider. MX only.

Thanks and my apologies for the novel, lol.

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7/31/2021 9:21 AM
Edited Date/Time: 7/31/2021 9:21 AM

Many of my friends are happy with the K-Tech conversion on their AERs. The K-Tech kit is pretty cheap and works very well IMO

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Unleaded tastes a little tangy. Supreme is kinda sour, and diesel tastes pretty good.

7/31/2021 11:02 AM

Depending on your budget, the MX Tech lucky kit is really good, still very lightweight, and not terribly expensive. You'll probably prefer the Lucky Gen 1 based on your age/skill level. Give them a ring and they'll sort you out.

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Billy Wight
Luxon MX
@LuxonMX
https://luxonmx.com
Motocross Components Engineered for Performance

7/31/2021 11:17 AM

These new forks are really tunable, i would consider a revalve, just reducing the tension on the midvalve trampoline takes out a lot of that spike and you can run higher pressure and have a more compliant fork. Don't forget, you can also alter oil level in the outer just like a spring fork.

In hindsight, I learned rhe biggest issue with airforks is poor shock setup, if the shock isn't holding rhe bike up, the forks don't work as well, especially in slap downs. The big HS comp adjuster makes a significant difference, wind it in quarter turn at a time. Also, if you've come off Japanese bikes, you kinda have to relearn sag setup.... measure the spring, and then add 7mm preload, which should give 105mm sag. If you need too much preload to get a bigger spring and round up not down.

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8/1/2021 3:02 AM

Luxon MX wrote:

Depending on your budget, the MX Tech lucky kit is really good, still very lightweight, and not terribly expensive. You'll ...more

I’ll add another vote for mx-tech. Their stuff is just so good and for a great price. I have kyb a kit and my next bike will very likely have mx tech Luckys instead

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8/1/2021 9:06 AM

Bruce372 wrote:

These new forks are really tunable, i would consider a revalve, just reducing the tension on the midvalve trampoline takes out ...more

Spot on! It's exactly what I learned in the last cpl of seasons with my KTM, Husky and now my GasGas450. I'm still running cone valves but I did do quite a bit of testing with the AER before deciding on the CVs and I found the getting the rear end working properly is the key to get the AER or the CV forks to work properly.

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8/1/2021 11:02 AM

This will take care of the fork issue, it is very much worth it. Photo

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8/1/2021 12:40 PM

Brent wrote:

This will take care of the fork issue, it is very much worth it. Photo

Don’t doubt it…unfortunately out of the current budget, lol

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8/1/2021 1:02 PM

Brent wrote:

This will take care of the fork issue, it is very much worth it. Photo

PNWRider wrote:

Don’t doubt it…unfortunately out of the current budget, lol

I used $6 worth of shims and a little suspension fluid for both ends.

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8/1/2021 2:14 PM

Keep it air and just revalve it.

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8/1/2021 9:21 PM

My old man loves the Lucky kit so far.

I think JBI make a leaf spring kit for the AER that has great reviews. Around $200 if I recall.

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21.5 350 XC-F
96' XR600r

8/2/2021 4:30 AM

I did the k tech on my 350 and it turned out great , especially for the money . You could do the install yourself if you've ever changed seals , really easy

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8/2/2021 9:20 AM

PNWRider wrote:

Hello All,
I picked up a 21 450 SX-F FE this year. Overall, it’s the best bike I’ve ever ridden, stock or modified. The only ...more

What rear spring are you running, stock 45nm or stiffer?

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8/2/2021 10:10 AM
Edited Date/Time: 8/2/2021 10:14 AM

PNWRider wrote:

Hello All,
I picked up a 21 450 SX-F FE this year. Overall, it’s the best bike I’ve ever ridden, stock or modified. The only ...more

I've got a set of lucky cartridges here that belong to a buddy. Neither of us were impressed, but he loves the National shock from MXTech. The lucky felt like an old 1996 open-chamber fork with a really good bottoming cone system (which it is). There was not much hold-up, but the extra damping at the bottom took the sting out.

He bought Cone Valves (48mm) and had them valved by FC along with his OEM shock. The shock was decent and the forks were very active and light on damping for him (225lbs 50+Expert) as well as me (160lbs 30A & 40A).

I went through the cone valves and tried shims in the mid-valve. We got them working well, but eventually decided to put the cones back in and mess around with the float / preload. The cones work well now, he likes them and runs them with the National shock from MX-Tech.

I've developed a kit that drops in any KX or YZ cartridges from a KYB 48mm AOSS or SSS fork.
Same buddy has a set of coated tubes with the larger 25mm internals from a 2020 YZ250F and 0.50kg springs.
The front end traction on that fork is better than anything I've ridden and the comfort is great.

I also have two other sets of forks out there being tested with my KYB kits:

2018 KTM 350SX-F 2018 YZ250 internals (220lbs 40+B rider) he loves them, especially on slapper landings.

2021 KTM 250SX 2021 YZ450F internals (200lbs age 26 local pro). He says the stock stuff was terrible in comparison.

KYB is the way to go in my opinion.
It improves the KTMs enough that my next new bike will probably be a GasGas or KTM 350.

There will be a less expensive solution for that available soon. The intent with that is that a fella can buy new cartridges from any Kawi or Yami dealer, Enzo or Tech-Touch and install them himself. The guy on a budget can find a set of good-used YZ or KX forks and gut them, install the kit himself. The third option is that a suspension tuner can do all the work and retail 100% of the parts with valving, springs, setup.

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8/2/2021 8:10 PM

Thanks everyone, you’ve given me a bunch to consider.

Aees, I’m running a 5.5 (not sure what that equates to in n-m) rear spring at the recommendation of FC (I’m 240).

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8/2/2021 8:19 PM

PNWRider wrote:

Thanks everyone, you’ve given me a bunch to consider.

Aees, I’m running a 5.5 (not sure what that equates to in n-m) rear ...more

That's about right, I am 240 also and running the 57 oem spring to get the right numbers.

Have you revalved the shock?

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8/2/2021 8:51 PM

PNWRider wrote:

Thanks everyone, you’ve given me a bunch to consider.

Aees, I’m running a 5.5 (not sure what that equates to in n-m) rear ...more

Bruce372 wrote:

That's about right, I am 240 also and running the 57 oem spring to get the right numbers.

Have you revalved the shock?

No, currently running stock f/r other than the rear spring. 105mm sag in the rear. Air at 156 psi in the forks. Can’t recall my clicker settings at the moment but they’re close to what FC recommended for base settings.

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8/2/2021 9:41 PM

I started another thread about the new WP XACT PRO 6500 cartridge inserts.

https://www.vitalmx.com/forums/Moto-Related,20/New-WP-XACT-Pro-6500-Cartridges,1393178

Like a KYB conversion, they appear to be dual spring, dual damping cartridge. Information on them seems a little sparse at the moment but it would appear these would drop right in, eliminating the need for changing the fork lugs or other mods. They also have external spring preload adjusters.

Interested to see how these do once they are out in the wild.

https://www.wp-suspension.com/procomponents/offroad/xact-pro-6500/

Photo

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Powerband in every gear !

8/2/2021 11:25 PM

I don't think any fork setup in the world will fix a bike with a poorly setup shock and the WP takes some figuring out since it isn't as forgiving as Japanese linkage rates, hence why luxon can fix the issue with math instead of shims

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8/3/2021 1:08 AM

PNWRider wrote:

Thanks everyone, you’ve given me a bunch to consider.

Aees, I’m running a 5.5 (not sure what that equates to in n-m) rear ...more

So there is an issue with ramp up of low speed comp when going to higher spring rates on the WP 2016 linkage. Not sure why any tuners does not seem to pick this up.

If you are right now in the middle of clickers of low speed comp (12-17), and 2.5-1.5 on hsc, just drop out 6-7 clicks on LSC to 21-23, and go in to around 0.75-1.00 on HSC.

This will make the forks feel about twice as compliant as before. LSC is pushing down the forks in the stroke way to much.

Test that, and report back.

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8/3/2021 7:12 AM

PNWRider wrote:

Thanks everyone, you’ve given me a bunch to consider.

Aees, I’m running a 5.5 (not sure what that equates to in n-m) rear ...more

aees wrote:

So there is an issue with ramp up of low speed comp when going to higher spring rates on the WP 2016 linkage. Not sure why any ...more

Checked my settings:

Shock:
LSC-15
HSC-2
R-13
5.5 spring, 105mm sag

Forks:
156 psi
C-14
R-20

The shock actually feels really good, but admittedly I’ve always focused more on fork feel-as long as the shock doesn’t kick up or sideways I’ve never been super picky. That said, I do understand that even if it feels good, it could be affecting the forks.

Thanks again for all the help and advice.

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8/3/2021 7:43 AM

PNWRider wrote:

Thanks everyone, you’ve given me a bunch to consider.

Aees, I’m running a 5.5 (not sure what that equates to in n-m) rear ...more

aees wrote:

So there is an issue with ramp up of low speed comp when going to higher spring rates on the WP 2016 linkage. Not sure why any ...more

PNWRider wrote:

Checked my settings:

Shock:
LSC-15
HSC-2
R-13
5.5 spring, 105mm sag

Forks:
156 psi
C-14
R-20

The shock actually feels ...more

Test this first:

Shock:
LSC-22
HSC-1.0
R-13
5.5 spring, 105mm sag

Forks:
156 psi
C-14
R-20

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8/3/2021 8:23 AM

FGR01 wrote:

I started another thread about the new WP XACT PRO 6500 cartridge inserts.

...more

I have used them and the feedback was very positive. Slightly stiffer base for mx, and the rider has been extremely happy.

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Livin' the dream, two wheels at a time!

8/7/2021 10:11 AM

Like Bruce says, sag set up and spring weight is crucial to get the WP fork working correctly.

Most riders have too much sag therefore the balance of the bike is off by a lot. I am happy with 102 mm currently.

Make sure that you are fully geared up in ALL of your riding gear before setting sag- you will also need two helpers to set correctly, every when using an electronics sag scale. Stand up in the middle of the motorcycle with no hands on the bars when setting sag.

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8/7/2021 4:34 PM

I am really struggling to understand how anyone can think these shocks have enough compression damping for anyone over 200lbs. Even with a big spring and turning the HS adjuster in, eventually it's really gonna make the bike kick in breaking bumps.

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