Fork length..

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Fork length..

Post by Tilts on Sat Nov 27, 2010 1:28 pm

My 400 forks where up as far as they could go, need to drop them to make them feel sharper whilst turning...any guide or set lengths to go by?
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Re: Fork length..

Post by nate on Sat Nov 27, 2010 1:55 pm

Try dropping them a line at a time and see how what they feel like bud, drop them too much and your front end wil get twicthy as it alters the geometry of the bike.

Mine are usually two lines down from the top and they seem perfect.

Just a quick question, have you set up your rear sag? It needs to be around 35 to 40mm static and 135mm to 140mm race sag. After you have set the static sag (do this first) if you cannot get the race sag correct it means the rear srping is too light for you. To give you an example (standard KTM spring is 12.5 stone)

Im 12.5 stone without my gear on and 13.5 stone kitted up, so even i would be on the upper limit of a standard spring bro.

rgds nate
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Re: Fork length..

Post by Tilts on Sat Nov 27, 2010 3:08 pm

Eibach heavy spring on the back, im about 20 stone with all my gear... sag is set near or there abouts... heavy springs in front as well. ive set them about 5mm under the bottom lines, up in the woods in the morning so ill see then....

Thanks Nate.
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Re: Fork length..

Post by booster24 on Sat Nov 27, 2010 8:28 pm

I dont think yor forks have preload, it could be that your forks are actualy too stiff and not settling into its working range thus increasing the the forks lengh. Put a cable tie on your forks around the sliders and see what the max range you are using. After that you will be in a better position to assess. Nates right what ever your static sag is there requires to be 100mm difference between race sag. Spent 22 years setting up sport bikes but the principles are excactly the same. Set my suspension up on the 400 tonight and it was well out, feels alot better now. But what ever you do have a note book to record pre and after ride and any adjustments made. If in doubt go back to standard and start again. Also if you have a new chain your wheel base will increase making the bike slighty harder to turn, but only by a nats cock.

See you soon Bud
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Re: Fork length..

Post by Tilts on Sat Nov 27, 2010 8:35 pm

Thanks dude,

not sure if i made myself clear, length as in the amount of over lap there is at the top of the yoke, mine were right up due to the bike being used for supermoto and a longer rake is better on the road, but make steering alot slower. Ive brought the forks up by about 15 mm, making the forks shorter, which hopefully will make turn sharper. as for sag, yep mine is set, but the sort of riding we do, you want to make it alot softer than normal, those sag settings are for full on racer's who jump and ride flat out..not quite our style. Very Happy
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Re: Fork length..

Post by booster24 on Sun Nov 28, 2010 9:32 am

I think the max you can go is 22mm bruv.
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Re: Fork length..

Post by Tilts on Sun Nov 28, 2010 1:50 pm

Cheers, just been out for a few hours, has made a difference.
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Re: Fork length..

Post by ogri on Wed Dec 01, 2010 10:58 am

Tilts wrote:Cheers, just been out for a few hours, has made a difference.


yep,bound too mate.kdx is ponderous even with 15mm showing above top yoke.feels like there is no side grip also.always have to work hard following someone along greasy or off-camber going.does feel stable compared to a ktm on faster going.....that is until you speed up enough til the sussies can't cope......which is not all that fast really.

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Re: Fork length..

Post by Tilts on Wed Dec 01, 2010 11:16 am

Remember taking my KDX along Sarn for the first time..... Shocked
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Re: Fork length..

Post by phil990 on Wed Dec 01, 2010 2:22 pm

Tilts wrote:Thanks dude,

those sag settings are for full on racer's who jump and ride flat out..not quite our style. Very Happy

Dear Mr Tilts.
On the KTM you can not increase the sag to make it softer! The shock has two Pistons. You need as much travel as possible with just the one piston without the secondary piston coming into play. Set the sag to large and all you get is overdamping. Not sure where in the travel the second piston comes into play. Its called PDS. A lot of top people on the older bikes(before 2008) just used to run the PDS with one piston and a large KYB bump stop. Great in the woods but not so good on doubles...

I hope that makes sence. That is why evrybody keeps saying that rear sag and spring are critical on a PDS KTM, and not always what the book says...
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