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2014 KTM350SXF FORK OIL HEIGHTS.

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Hello from
Brisbane, Australia..
 

I purchased my new 2014 KTM 350SX kato in dec 2013 and sprung a brake side fork seal leak after ONLY 1 HOUR. shocked definatly,
and as per the warrenty book I had to take my bike on for a full ridiculously priced service to where I bought the bike from
 which I got the reply sorry no warrenty on fork seals even if it only has 1 hour on it!
   Thanks Team HOMO!!
  
 The weep was pretty minor and the seal seemed to last up until  now at 5 hours, even after trying the SEAL DOCTOR
method on the seals to no avail...
 
 I guess now I have to replace BOTH seals for precaution?
Whilst the forks are in the shop I was wonder about what fork oil height/weight should be used for my riding style and weight?

Im 75kgs. do around 80foot jumps..not a pro just for fun..
 
 Bike is standard and rear shock I have the ride sag at 100mm.
 
I got to ride  the 2014 YZF450 on a test day and like the fork suspension and from what I have read the YAMI's are the best suspension...
I like the way the yami absorbs the small bumps but still resists bottoming out...
 
  I would love to hear your insight if in fact just changing fork oil height or oil weight or even taking or adding fork shims would
be any good for my weight and help be a little better at absorbing the smaller bumps on the track...
 The forks just seem a little harsh, I have played around with the clickers and fork height in the triple clamps.
Is 5 hours a little too soon to be changing fork oil weights and heights?

 

Any other mods and tricks you may have for this bike would be great to know..
 
   Thanks in advance for your insight.
Kind regards!!
   

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Yea, the oil seal failing isn't good news, I can't imagine how it went bad because they're pretty robust. Maybe something wrong with assembly?

So spring rate is determined by measuring sag. For motocross, you wanna be in the 50 - 60mm range rider sag in the front. Oil height is then determined by bottoming resistance. Put a zip tie around the bottom tube, side it all the way up and go ride, over jump a few things with high (380cc) oil height and see what happens. You should have the fork setup to have 20mm of unused travel at the bottom of the tube. Some tuners prefer more, some tuners prefer less. I find with 20mm, thats enough so if you do hit something really bad, something out of the ordinary, you still have SOME resistance down there. So if you're at 50mm of exposed tube or something with 380cc's, then lower it to 370cc and try again. I usually do this at the track, simply taking the forks off, unscrewing the cap and using a graduated cylinder, pouring just the right amount of fluid out and re-installing the forks.

Oil height is critically important to the bottoming resistance of the machine. So don't go too low... the lowest I'd go with those forks is 350cc.

In terms of Yamaha suspension... well I personally don't like it. However, they use an IFP spring and the nice thing about IFP springs vs bladders or high-pressure IFP systems like the Öhlins, is that the springs can be ultra light at the top end of the stroke. So when the fork is full extended going over small chatter bumps, there isn't a great deal of pressure on the oil. When you increase the pressure, you increase the damping resistance and as a consequence, the fork gets stiffer. The WP closed cartridge bladder forks biggest ailment is the necessity of running a considerable amount of pressure in the bladder to avoid cavitation and create a compliant feeling. As a consequence, air/nitrogen in a bladder or IFP, exponentially gets stiffer every time you compress it. So as the shaft travels through the stroke, the fork is getting stiffer and stiffer just from the built-up pressure. With a spring IFP, it can be much more linear and WAY plusher.

Unfortunately, there is no way to make the WP Closed Cartridge bladder forks on the KTM SX models, feel like a well setup spring IFP fork like the Showa or KYB. The funny thing is, the factory KTM forks are just like the Showa's with spring IFP's... easier to maintenance and more plushness.

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Hey mate in brissy as well. Call Darren at db race suspension and tell him aldo sent you 0422187640 ,he's at chambers flats near browns plains. His personal bike is ktm and me and my friends are all happy with his setup. I went a bit crazy with This time and got jbi spring perch in the forks and mxt check valve in the shock and is unreal.

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How much did you drop in your suspension Aldo?

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800, 500 In parts. I've been super happy with just his revalves in the past. My 12 250sxf was night and day difference after his revalve. I'm taking a different approach with this bike, if Its not going to help me get faster I don't need it.

I'm back home for 2 weeks this Thursday PM me and I might meet you at Qmp and you can take it for a spin.

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