Posts
9
Joined
3/28/2016
Location
San Diego, CA
US
Edited Date/Time
4/5/2016 12:27am
Hey guys. I have a 2015 KX450 and i'm struggling with front end traction on the bike. In stock form, the first inch or so of travel was very stiff and harsh and i felt like i had to tip toe around corners, and overall had little confidence in laying the bike over in corners. The rest of the action felt pretty good past that first inch of travel.
After getting the forks rebuilt and revalved by a well known California suspension company, that first inch of travel was a little more plush, but still harsher than it should be. Elsewhere, the fork is fantastic.
It's super noticeable and extremely frustrating that i don't have confidence in the front end traction. I feel that my corner speed is effected because of it.
I've tried a number of things to try to fix it:
Rear Sag set at 105mm - This was recommended.
Lower tire pressure to 10psi (normally run 11.5-12.0) - helps a little
Slide clamps down in the forks - the frond end knifes in corners and i get headshake at speed
Few clicks softer on compression damping - front end dives under braking
Few clicks harder on rebound damping - Little improvement, but theres a tendency for the front end to fly high on jumps.
I've ridden the 2015 and 2016 YZ450f back to back with my bike, and its such a huge difference. The Yamaha just has so much front end traction in comparison, so much that I'm really thinking about getting rid of the kawi. Its a night and day difference!
Anyone else struggling with front end traction with the Showa SFF TAC fork? If not, what is your secret?
After getting the forks rebuilt and revalved by a well known California suspension company, that first inch of travel was a little more plush, but still harsher than it should be. Elsewhere, the fork is fantastic.
It's super noticeable and extremely frustrating that i don't have confidence in the front end traction. I feel that my corner speed is effected because of it.
I've tried a number of things to try to fix it:
Rear Sag set at 105mm - This was recommended.
Lower tire pressure to 10psi (normally run 11.5-12.0) - helps a little
Slide clamps down in the forks - the frond end knifes in corners and i get headshake at speed
Few clicks softer on compression damping - front end dives under braking
Few clicks harder on rebound damping - Little improvement, but theres a tendency for the front end to fly high on jumps.
I've ridden the 2015 and 2016 YZ450f back to back with my bike, and its such a huge difference. The Yamaha just has so much front end traction in comparison, so much that I'm really thinking about getting rid of the kawi. Its a night and day difference!
Anyone else struggling with front end traction with the Showa SFF TAC fork? If not, what is your secret?
Also, don't forget there are also compression and rebound adjusters on those forks. I'd be using those for the tracks with the bigger or smaller jumps. Use the pressure settings as a baseline for your body weight and overall speed.
The Shop
Do i have my understanding correct? If there is too much rebound damping in the fork, it will take longer for the front wheel to return back to the ground after hitting a bump. This would mean the front wheel would be unloaded. In that case, i'd remove rebound damping and should see more traction.
On the flip side, if the comp is too soft, i could be diving into the harsher mid stroke too soon, forcing the wheel to deflect more often over the small chop.
Is the ideal scenario to have the fork within the first 1/4 of travel in corners? Is there some sort of target suspension tuners aim for?
I may just have to play with the clickers some more.
The pressures changed drastically for me from when the fork was stock to when I had it re-valved, there are too many factors that effect the pressures such as speed, style, track type/speed, preferred fork feel, valving etc.
To get these forks to work, you simply need to test.
Go to the flattest, simplest track you know of and you will be amazed how much you will learn about the fork. A simple track will allow you to concentrate completely on the fork and how it feels.
Set your clickers somewhere neutral and play with pressures first, you don't necessarily need to find the right pressure, but experiment until you understand how the relationship between inner and balance effects the fork action and feel. Take notes and record your findings
I never had any luck with the outer chamber, and prefer to leave it at 0. Pressure in the outer chamber increases fork stiction and will likely be a large cause of the low grip you're suffering due to poor fork sensitivity.
Set your inner pressure simply by placing a zip tie around one fork leg, and find a pressure that uses near full travel without harsh bottom out. Once you've found a pressure that works on a wide range of tracks, record the pressure and never change it again. Use compression/rebound and balance chamber to adjust from then on.
Always adjust the fork in the proper way. COMPLETELY empty the balance chamber, then set the inner, then re set the balance, do this for every single adjustment. Ensure the front wheel is completely off the floor and the fork fully extended.
A Works Connection no loss adapter is a fantastic investment, order one now if you haven't got one already
Interesting note about the outer chamber pressure. I'll have to play with that a bit. I have heard of guys running 0 psi in the outer with good results, however i felt like the fork lost bottoming resistance when i did that. I have not tried to run 0 psi in the outer after getting it revalved so i'll try that out next time at the track.
Great suggestion about the zip tie! I'm definitely going to try that out next time i'm at the track.
I always follow the that pressurization procedure, as well. Balance chamber deflated, wheel off the ground, then fill inner > outer > balance.
Also, download the Showa SFF AIr Support app on your phone. This is a great tool that uses graphs to illustrate how a change will effect the damping curve of the fork. This takes the guess work out of making changes, allowing you to see what change is best for the desired outcome
I have a 2015 KX450, currently running 140 inner/5 outer/150 balance.
I really like it...but I still find myself deflecting off rocks (like a gnarly rocky section "baby head sections" is what we call them)...the front end just seems busy and unplanted (relative to the KYB SSS forks on my Yamaha at least).
Any thoughts are appreciated....
I don't really worry about bottoming all that much-besides the G-out, or whoop section-so I'm going to try the 0psi in the outer chamber...according to the Showa SFF app, it drastically softens middle to bottom...and if it will reduce the "stiction" in the initial travel...maybe it will help in the rocks?
So I tried running the following setting with 0psi in the outer chamber. To get a similar spring feel out of the fork, i had to run much less balance chamber pressure:
Here is how the force graphs look for each profile in the SFF Air app:
(PINK) Previous settings - 180 inner / 10 outer / 190 balance / 320ml Oil
(TEAL) Test 0psi settings - 188 inner / 0 outer / 150 balance / 320ml Oil
(YELLOW) Stock - 145 inner / 7.2 outer / 131 balance / 340ml Oil
As you can see, 0 psi in the outer lends for a more linear spring curve as the expense of bottoming resistance.
With the test settings, i noticed that the fork was noticeably more plush and i had a little more front end traction, but strangely it made the steering feel heavy (does that make sense?). To compensate for the lack of bottoming resistance, i had to slow the compression damping by going 6 clicks out and speed up the rebound damping by going 14 clicks out! I feel like this setup is a trade off because where i gained in cornering, i lost in bottoming resistance, and so i found myself blowing through the stroke on bigger jumps. The track i was at has a high speed downhill section (4th gear on my 450) and i felt like the front end was packing deep into the stroke, even with the clickers set as they were. I think this setting is a step in the right direction, and I'm also thinking about bringing the oil level up to about 380ml to add some bottoming resistance. It would bring the force curve more in line with my recommended 180/10/190 setting without the stiction of pressure in the outer chamber.
Having said all that, I think my green bike is fantastic in most other areas, and the motor is great. But i think i'm at the point where i'm ready to sell this bike and go with a different color that doesn't have air forks. I told myself this when i jumped on a new blue bike and instantly felt faster and more confident.
Dirt Rider's Nick Envenou has been putting on of these to the test with an otherwise stock suspension setup: http://www.dirtrider.com/long-haul-update-2016-kawasaki-kx450f
Don't forget to mention VitalMX if you decide to try one out, there is a discount for all Vital members at Race Tech. I can help you with any questions or a quote at chris@racetech.com
This might sound backwards, but now you have figured out the IC/BC relationship and got a fork feel you are happier with, try adding air to the outer chamber.
It's clear the cause of your previous problems were mainly from your BC pressure being far too high, and not so much the 10psi outer chamber setting. Your fork was sunk in the travel and not reacting to the terrain, giving the poor feeling in the corners.
You may find you don't need 10psi in the outer anymore, due your latest increased air chamber and compression settings. Start with 5psi and go from there.
If however the outer chamber pressure begins to create harshness, then try adding oil.
The balance chamber works against the inner chamber, having a balance chamber pressure higher than the inner chamber pressure shortens the fork. A high balance chamber + the weight of you and the bike would have had the fork dropped in the travel.
You have added 8psi to the inner, reduced the balance chamber pressure by 40psi and increased compression... all of which stiffen the fork. If you now start to add air back in the outer chamber pressure, you will improve the bottom resistance as well as stiffening the overall feel of the fork.
Also, did the suspension company who did you re valve not give you recommended pressures? It seems odd for a company to tweak the valving and then not give air settings to suit. A good suspension company should be able to provide a valving and setting package that is close, if not spot on to your needs.
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