2018 KX450 SFF-TAC setting question

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7/10/2018 1:12 PM

Hello all. I just picked up a new 2018 KX450F. Although I will be most likely picking up a spring conversion, I have to wait to do that for a couple months ($$$). Plus I wanted to ride the bike first to see what I like, don’t like, and to break it in so that the conversion also covers the first fluid change.

I am 5’11”/230, over 40B/C rider. I jump most everything on local tracks. Rear spring is a 5.8 for my weight. Sag is 105mm.

I initially used MXA’s “Vet” settings (138 IC, 16.5 OC, 160 Bal). Overall I like them and to be honest the forks weren’t bad at all. However, even though small chop is a little harsh, I feel like it conversely blows through on big hits. I upped the inner to 145, then played with compression. I ended up pulling the compression back out as it got harsher on small stuff without much benefit on the big hits (jump landings, rythym section faces).
So I’m a little confused. On the only other air forks I had (2013 KX), air pressure was set to a setting that was the equivalent of picking proper fork springs for your weight, then any other tuning was the same as a spring fork. But from my searches, it looks like the air pressures are part of the tuning?

My ideas were:
Add more inner pressure (I’d think this would be like going too high on spring rate)
Add outer pressure (but I’m already at 16.5)
Add oil height to left leg
?

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7/10/2018 1:20 PM
Edited Date/Time: 7/10/2018 1:21 PM

Ok, First suggestion. Just throw the TAC fork in the trash. Really. I've got an A kit i'll sell cheap that I probably wont even get to taking off my bike for a month or two as im on the mend right now.

140PSI on the inner seems way low. THats like your spring rate , or air pressure on your old PSF forks (which I had a 13, and they worked much better than the TAC's did in my opinion). Adding that much air to the outer chamber makes the fork feel funny almost like it binds.

I havent played with the TAC since I stuck it in th eattic and put a kit spring forks and a kit shock on my 16 back in 16, but 140 range seems way to low on the inner (spring rate) for 230 pounds.

Give something like 175 Inner, 6 Outer, 180 outer a try. Go up on the inner pressure if it feels like it dives to much. The more balance you add the lower the fork is going to want to ride in the stroke on its own, which will lend its hand to you feeling "harshness" in the forks. I suspect you think they feel soft on the big stuff because youre so low on the inner pressure.

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7/10/2018 1:45 PM

Welcome to the world of TAC air forks! I bought a 15' when the first came out and beleived the hype around these forks. 4 painful years later, I fainlly ditched the bike and went back to one with spring forks.

What i had the most success with was an RG3 setup. Then they had me run equal pressure (190 psi) in the inner and balance chamber and pull all the air out of the outter. The way they explained it to me was by doing this your essential making it as close to a spring fork as possible by running the equal pressure.

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I don't crash, I just run out of talent

7/10/2018 2:41 PM

Bad advice, dmm. The fork is not trash so long as you know how to set it up properly. I love mine.

omalley, you should first download the SFF-Air app on your cellphone. It really helps you visualize how each chamber effects the overall curve.

On the SFF TAC fork, the combination of the 3 chamber pressures is what defines your overall spring rate curve. So, yes, its a spring at the end of the day. Once you find your happy setting you shouldn't need to change from those settings. You should be able to use the clickers to dial in the feel you want for a particular track or condition after that. Expert tuners will use all 5 settings (Inner/Outer/Balance/Comp Damping/Rebound Damping) to really dial in the fork.

-Inner pressure effects the overall force curve.
-Outer pressure effects the last half of the stroke (bottoming resistance).
-Balance (negative) pressure effects the overall curve, but mainly the first half of the stroke. It is super important, especially with the 16-18 TAC fork, that you have the balance chamber pressure at least 15% higher than the inner pressure to achieve initial plushness in the fork.

The very first thing you should do is set your compression and rebound clickers to the factory settings. For your bike, that is 9 clicks out on compression, and 13 clicks out on rebound.

138/16.5/160 is way too soft for your weight. You are likely blowing through the stroke into the mid range.

The standard setting for a 170lb'ish rider is 174/14.5/203.
The "soft" setting is 160/14.5/174.
The "stiff" setting is 189/14.5/218.

I recommend trying the standard setting to start, just to see how it feels. Then try the "soft" setting and the "stiff" setting. Compare how each of the settings feel.

Also very important is how you set the pressures in this fork. Bike needs to be on the stand with the front wheel off the ground. First, deflate the balance chamber. Second, deflate the outer chamber. Then fill inner > outer > balance to your desired pressures. The reason for this is that any pressure in the other chambers actually effects the inner pressure reading.

Report back what you have tried and i will try to help.

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7/10/2018 3:35 PM

Thanks everyone. Bryan, will do. I tried to get the app (IPhone) but the App Store says it’s not available?

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7/10/2018 5:00 PM

omalley wrote:

Thanks everyone. Bryan, will do. I tried to get the app (IPhone) but the App Store says it’s not available?

It’s apparently not available in the US. Which I’m bummed about cause it looks pretty cool

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RPM Performance
CT
783

7/11/2018 8:15 AM

omalley wrote:

Thanks everyone. Bryan, will do. I tried to get the app (IPhone) but the App Store says it’s not available?

I downloaded it with my new phone few months back. Did you go to American showa website? I think it's offered there.

Yes very good fork. I've done more 17s and 18s, and the forks overall performance has increased.

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Livin' the dream, two wheels at a time!

7/11/2018 10:35 AM
Edited Date/Time: 7/11/2018 10:38 AM

theycallmeebryan wrote:

Bad advice, dmm. The fork is not trash so long as you know how to set it up properly. I love mine.

omalley, you should first download the SFF-Air app on your cellphone. It really helps you visualize how each chamber effects the overall curve.

On the SFF TAC fork, the combination of the 3 chamber pressures is what defines your overall spring rate curve. So, yes, its a spring at the end of the day. Once you find your happy setting you shouldn't need to change from those settings. You should be able to use the clickers to dial in the feel you want for a particular track or condition after that. Expert tuners will use all 5 settings (Inner/Outer/Balance/Comp Damping/Rebound Damping) to really dial in the fork.

-Inner pressure effects the overall force curve.
-Outer pressure effects the last half of the stroke (bottoming resistance).
-Balance (negative) pressure effects the overall curve, but mainly the first half of the stroke. It is super important, especially with the 16-18 TAC fork, that you have the balance chamber pressure at least 15% higher than the inner pressure to achieve initial plushness in the fork.

The very first thing you should do is set your compression and rebound clickers to the factory settings. For your bike, that is 9 clicks out on compression, and 13 clicks out on rebound.

138/16.5/160 is way too soft for your weight. You are likely blowing through the stroke into the mid range.

The standard setting for a 170lb'ish rider is 174/14.5/203.
The "soft" setting is 160/14.5/174.
The "stiff" setting is 189/14.5/218.

I recommend trying the standard setting to start, just to see how it feels. Then try the "soft" setting and the "stiff" setting. Compare how each of the settings feel.

Also very important is how you set the pressures in this fork. Bike needs to be on the stand with the front wheel off the ground. First, deflate the balance chamber. Second, deflate the outer chamber. Then fill inner > outer > balance to your desired pressures. The reason for this is that any pressure in the other chambers actually effects the inner pressure reading.

Report back what you have tried and i will try to help.

Again, the fork is trash. I'll stand behind that. If it wasnt, kawasaki wouldnt of taken a big weight penalty to ditch it on the new bike, and put a spring fork back on.

I tried that "standard setting", was awful.
I'm competent in suspension. I understand how an Air spring works, and it'll always be more progressive than a standard spring.

I'm stoked for you if you like that fork on your bike, but i'd challenge you to put a decent spring or kit fork on that bike and it would probably open your eyes to what that bike COULD be.

You want to know the absolute worst thing about the TAC fork? You can ride Track A on a monday with weather being X deg/%humidity and it may feel decent. Come back on friday, same track, same weather, same surface prep/braking bumps, and the bike will feel like complete dog crap.
I really wanted to give the forks the college try, and they were SO bad that they translated to me believing there was a significant shock issue with the bike, and 2 revalves of the shock later I gave up.

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7/11/2018 5:59 PM

dmm698 wrote:

Again, the fork is trash. I'll stand behind that. If it wasnt, kawasaki wouldnt of taken a big weight penalty to ditch it on the new bike, and put a spring fork back on.

I tried that "standard setting", was awful.
I'm competent in suspension. I understand how an Air spring works, and it'll always be more progressive than a standard spring.

I'm stoked for you if you like that fork on your bike, but i'd challenge you to put a decent spring or kit fork on that bike and it would probably open your eyes to what that bike COULD be.

You want to know the absolute worst thing about the TAC fork? You can ride Track A on a monday with weather being X deg/%humidity and it may feel decent. Come back on friday, same track, same weather, same surface prep/braking bumps, and the bike will feel like complete dog crap.
I really wanted to give the forks the college try, and they were SO bad that they translated to me believing there was a significant shock issue with the bike, and 2 revalves of the shock later I gave up.

I tested Ohlins RXF48 kit forks on my bike and didn't really like them. My Showa SFF TAC forks with RaceTech gold valves performed better in my back to back to back tests.

Photo

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7/11/2018 6:13 PM

I'd like to see a head to head with tac forks and retrofitted spring forks. Not a single spring conversion, but a legit spring fork swap. And, not a 19 to 18 comparison.

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Livin' the dream, two wheels at a time!

7/12/2018 6:14 AM

m21racing wrote:

I'd like to see a head to head with tac forks and retrofitted spring forks. Not a single spring conversion, but a legit spring fork swap. And, not a 19 to 18 comparison.

I removed the TAC forks and installed 49mm PC A kit forks and the matching shock. So probably not a fair comparison.
A buddy and also a member here maybe chime in, put some 2012 era KYB spring forks from a kx450 on his 16. One fork has mystery valving in it from an unknown tuner, and the other one is stock in the mid valve at least. He slapped them on his bike and they were such an improvement over the factory connection revalved TAC fork he left them on.

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7/12/2018 9:59 AM

m21racing wrote:

I'd like to see a head to head with tac forks and retrofitted spring forks. Not a single spring conversion, but a legit spring fork swap. And, not a 19 to 18 comparison.

I went from a revalved TAC fork (factory connection) to a set of 2010 KX450F KYB spring forks. The springs are more comfortable over chop for sure. I prefer them... that being said, the TAC is not terrible if set up right. I'd say I had mine 85% of where I wanted them, just couldn't get that last little bit of feel on some track conditions. I got a good deal on the KYBs so I pulled the trigger, but if the price wasn't so low I probably would have just stuck with the TACs.

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7/12/2018 10:21 AM
Edited Date/Time: 7/12/2018 10:26 AM

omalley wrote:

Hello all. I just picked up a new 2018 KX450F. Although I will be most likely picking up a spring conversion, I have to wait to do that for a couple months ($$$). Plus I wanted to ride the bike first to see what I like, don’t like, and to break it in so that the conversion also covers the first fluid change.

I am 5’11”/230, over 40B/C rider. I jump most everything on local tracks. Rear spring is a 5.8 for my weight. Sag is 105mm.

I initially used MXA’s “Vet” settings (138 IC, 16.5 OC, 160 Bal). Overall I like them and to be honest the forks weren’t bad at all. However, even though small chop is a little harsh, I feel like it conversely blows through on big hits. I upped the inner to 145, then played with compression. I ended up pulling the compression back out as it got harsher on small stuff without much benefit on the big hits (jump landings, rythym section faces).
So I’m a little confused. On the only other air forks I had (2013 KX), air pressure was set to a setting that was the equivalent of picking proper fork springs for your weight, then any other tuning was the same as a spring fork. But from my searches, it looks like the air pressures are part of the tuning?

My ideas were:
Add more inner pressure (I’d think this would be like going too high on spring rate)
Add outer pressure (but I’m already at 16.5)
Add oil height to left leg
?

We are similar weight and speed. Try these fork settings (they are going to sound weird compared to where you are now, but believe me). I'm really picky with setup, and this is the best I could figure out. It even seemed backwards from what I expected, but it works. The higher balance pressure holds the fork down, which balances out the higher sag and lower fork height and makes the bike stable, but handle nice.

You will probably have to "reset" you pressures to make a large pressure change like that by bleeding the balance off, setting the Inner, then the outer, then finally the balance.

Sag: 108 mm
Fork height: 2.5 mm
Fork pressures: 155 inner, 10 outer, 217 balance

Really the biggest challenge with the air fork is people playing with fork pressure rather than clickers. Once you get a pressure that feels good, keep it constant and then just adjust the damping fork.

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7/16/2018 1:20 PM

theycallmeebryan wrote:

Bad advice, dmm. The fork is not trash so long as you know how to set it up properly. I love mine.

omalley, you should first download the SFF-Air app on your cellphone. It really helps you visualize how each chamber effects the overall curve.

On the SFF TAC fork, the combination of the 3 chamber pressures is what defines your overall spring rate curve. So, yes, its a spring at the end of the day. Once you find your happy setting you shouldn't need to change from those settings. You should be able to use the clickers to dial in the feel you want for a particular track or condition after that. Expert tuners will use all 5 settings (Inner/Outer/Balance/Comp Damping/Rebound Damping) to really dial in the fork.

-Inner pressure effects the overall force curve.
-Outer pressure effects the last half of the stroke (bottoming resistance).
-Balance (negative) pressure effects the overall curve, but mainly the first half of the stroke. It is super important, especially with the 16-18 TAC fork, that you have the balance chamber pressure at least 15% higher than the inner pressure to achieve initial plushness in the fork.

The very first thing you should do is set your compression and rebound clickers to the factory settings. For your bike, that is 9 clicks out on compression, and 13 clicks out on rebound.

138/16.5/160 is way too soft for your weight. You are likely blowing through the stroke into the mid range.

The standard setting for a 170lb'ish rider is 174/14.5/203.
The "soft" setting is 160/14.5/174.
The "stiff" setting is 189/14.5/218.

I recommend trying the standard setting to start, just to see how it feels. Then try the "soft" setting and the "stiff" setting. Compare how each of the settings feel.

Also very important is how you set the pressures in this fork. Bike needs to be on the stand with the front wheel off the ground. First, deflate the balance chamber. Second, deflate the outer chamber. Then fill inner > outer > balance to your desired pressures. The reason for this is that any pressure in the other chambers actually effects the inner pressure reading.

Report back what you have tried and i will try to help.

Thanks for the great breakdown. I went to the standard (174/14.5/203) setting. Here’s what I found.

-overall feel is worlds better, especially on steep jump faced and rhythm sections. Nice firm progressive feel which is what I shoot for in a set of forks.
-I still have a hint of bottoming on flat landings and bigger hits, but it’s minimal and I’m inclined to leave it.
-I am experiencing rebound issues on said bottoming events. It’s like the fork is springing back enough to make it pogo weightless momentarily. I really noticed it on a step up where you fly as far as you want onto flat ground. The track curves there and I fought the pogo enough that my turn in was delayed. Wasn’t sure if this is a rebound issue or balance pressure issue.
-the bike turns like crap now, I suspect because the forks are riding higher in the stroke. Wasn’t sure if more balance pressure would help them settle, or to go less compression like a standard fork.
-Small chop is harsh. It wasn’t good before either, so it may be a valving issue.

Thanks again!

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7/16/2018 7:11 PM

omalley wrote:

Thanks for the great breakdown. I went to the standard (174/14.5/203) setting. Here’s what I found.

-overall feel is worlds better, especially on steep jump faced and rhythm sections. Nice firm progressive feel which is what I shoot for in a set of forks.
-I still have a hint of bottoming on flat landings and bigger hits, but it’s minimal and I’m inclined to leave it.
-I am experiencing rebound issues on said bottoming events. It’s like the fork is springing back enough to make it pogo weightless momentarily. I really noticed it on a step up where you fly as far as you want onto flat ground. The track curves there and I fought the pogo enough that my turn in was delayed. Wasn’t sure if this is a rebound issue or balance pressure issue.
-the bike turns like crap now, I suspect because the forks are riding higher in the stroke. Wasn’t sure if more balance pressure would help them settle, or to go less compression like a standard fork.
-Small chop is harsh. It wasn’t good before either, so it may be a valving issue.

Thanks again!

Glad it feels better.

Regarding turning, sounds like you mean turn in. Where are your forks in the triple clamps? If the fork caps are flush with the top clamps, i suggest sliding the forks up about 5mm in the clamps.

Sounds like the pressures are much closer to where you should be. I suggest focusing on clicker adjustments to get it where you like it. Were you at the standard 9C/13R ? Try going a click or two in on the compression damping and see if that resolves the bottoming without sacrificing front end traction. Once you fix that, then go in on the rebound damping a a click or 2 to dial away that pogo effect. If you get to the point where you are less than 5 clicks out on compression, you'll need to think about going a little stiffer on the pressure settings. At that point i would recommend backing the compression clicker out to the standard 9 out setting and then adding 1-2psi to the outer chamber for added bottoming resistance. If it's still bottoming like that, go in a click or two on the compression until its gone.

If all that doesn't make it feel better, RaceTech recommends 165.5 inner/ 18.0 outer / 183.5 balance for your weight and skill level.

I have the 2015 version of these forks and the chambers are slightly different, but i'm running 180/10/190 with my RaceTech valving and it's spot on for me. All i do is adjust clickers a few clicks either way depending on the track and its really confidence inspiring.

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7/16/2018 8:33 PM

The bike turning bad is from the forks riding too high. Try those settings I listed above. Also, moving the axle back to put more weight on the front wheel (adding a link to the chain) really helps with turn in on these bikes. Check any pitbits of MX or GP kawis and you'll see they run their axle back.

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