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Old 02-26-2013, 01:02 PM   #136
naginalf
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Some research

Thought I'd share some recent research into these forks and post some links to helpful info.

First of all, there were some changes made in 2005 to reduce stiction. Prior to this, there were 3 bushings and no oil relief, so they liked to blow seals. Many were drilling holes in the tubes to relieve this pressure, and they were removing the third bushing and spacer, replacing them also with KYB parts. See this thread for more info, although you'll have to dig a bit. Pay attention to the Terry Hay member. Oh yeah, you'll need to register to see these KTMtalk threads.

Although, after 2004, WP installed an oil channel for pressure relief, they still recommend drilling the hole as it may not be enough.

Also, this thread is quite useful for parts ID and breakdown. It also details some of the mods.

I was originally looking for recommendations on shim stacks. I first found this thread with several examples for KTM 990 adventures which are close in size to our bikes. Slackmeyer seems to have the most input with a very nice chart of changes he has made. The other charts only include the compression stack, but slackmeyer has covered the midvalve and rebound in 2 revisions. Here's another thread with more options and links. Head 2 Wind may be a setup I'll try since he's about my size.

If you just want the easy way out and have someone send you the proper parts and valves, I found several companies that seem helpful in the matter. There's SuperPlush who not only cater to the bigger bikes, but also have perfect, short, heavier springs and custom spacers for shortening . They were willing to take my specs and send me everything I need to set my valves and rebuild with new springs and spacers, I've read people gushing over their setups. There's also MX-Tech who have dealers in several places and are based out of Illinois.

If you REALLY want to get all technical, you can struggle on the uphill battle of figuring out how to use Shim Restackor and apply it to real life. One of the previously linked ADV threads goes into more detail about it and gives good examples, but not much in how to actually USE it. I think I'd rather simply have someone tell me what to do and sell me the proper parts.

Custom springs can be had from Sonic or Slavens. Others previously mentioned may be able to help with that as well. But, if you are shortening these forks to match OEM height, be sure to order shorter springs or you'll be adding preload. Slavens also has some great how to vids. Recommended spring rates seem to range from .52 to .65 for bikes our size. Head2Wind has .6 in his and are slightly harsh, that's 250lb rider + 460lb dry weight bike, almost exactly our bike size. Slavens recommended .64 for me. I may order two different sizes.

And make sure to use the SKF fork seals for reduced stiction.

Prutser mentioned here somewhere that you may wish to shim out and file the edges of your bushings. There are a bunch of other mods that have been discussed in these threads I've posted. Some of them sound downright sensible, Head2Wind gives quite the list of them.

More good info here, here, here, here, comprehensive video for sale here, and dis/assembly manual here.
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Old 02-26-2013, 01:39 PM   #137
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Thanks a lot for that. To keep some of this info in one spot, the front axle on the WP4860 switched from a 20mm to a 26mm in '03. There are axle adapter kits available to fit old axles in new forks. 2007 was the first year that the fork went from an open chamber fork to a closed chamber(edit: only the SX. some switched later, thanks AW). The article posted earlier makes a strong argument for sticking with the open chamber fork for a travelling bike. Sounds like an '05 or an '06+ would be the best years to get.
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Old 02-26-2013, 01:46 PM   #138
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Originally Posted by bgoodsoil View Post
The article posted earlier makes a strong argument for sticking with the open chamber fork. Sounds like an '05 or an '06 would be the best years to get.
Not ALL of them went to a closed cartridge or "dual chamber" as they call them. Only the SX models at first in '06. I think some are still open cartridge to this day. Some say that quality control got a lot better in 2010 when KTM moved production to austria and the quality of the sliders in particular is much better which helped with the stiction issues. Also SKF seals were used from 2010 on so that helped with the stiction a lot too.

EDIT: current model year EXC and XC-W models still use open cartridge forks. KTM's website lists open cartridge forks as 4860 MXMA PA forks where as closed cartridge ones are listed as 4860 MXMA CC.
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Old 03-11-2013, 05:32 PM   #139
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New info and a good suspension guy

Ok, I have unsuccessfully contacted several suspension shops who might cater to a DIY rebuild and revalve. None of them seem to want to work with me . Well I found out why today.

The one, most friendly, helpful contact I have made is with Kelvin at CSR, who says he was taught by WP, taught many others himself, and was an initial distributor for WP, is very experienced in them. He also said that many of even the big name suspension tuners out there are doing it wrong. For instance, the WP manual details oil level setting wrong because they copied the old method by accident. This guy seemed very knowledgeable about all the subtle changes made in WP forks (and there have been A LOT) that drastically change behavior and has all the fixes for them like bigger valves to reduce deflection. They may look the same to the untrained eye year to year, but said that in order to work on these older forks, he'd have to dig up some notes. He mostly works on newer ones which are much different despite the similarity.

One major issue is shim deformation, especially in the older models. Apparently WP has implemented only in the past couple of years a fix for this, that no one, not even he or WP understands clearly. I'll give more details when I get the parts and dig in.

Kelvin also said that this is NOT, I repeat NOT a job for the unskilled or faint hearted, which is probably why I've been having a lack of response. Suspension guys are laughing at my emails. With an increase in complexity of valving, it becomes very difficult to simply say, "this is what you need." Change one valve wrong and it isn't balanced with the other two AND the spring rate properly, and the whole system is mucked up. There are also many things to know about before wrenching on the insides. One small tip for instance, the threads that hold the shim stacks must be cut in order to get the nut off, it is deformed in order to keep the nut from falling off should it loosen. I mentioned the rebuild videos that Slavens has posted, and he said, "yup, I'm the one who taught him." So Slaven's videos are the ones to watch. But despite the reservations, he said he's willing to work with me and answer any questions. Really a great guy!

So anyway, I'm gonna try to do this myself, and he'll make me up a set of shims and springs and all the parts upon request and build me a kit. He said that having him do the rebuild, lowering, and revalve would cost $7-800 and I don't have that kind of cash. Once I get the parts, I'll let you all in on the details.
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Old 03-11-2013, 05:40 PM   #140
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Originally Posted by naginalf View Post

So anyway, I'm gonna try to do this myself, and he'll make me up a set of shims and springs and all the parts upon request and build me a kit. He said that having him do the rebuild, lowering, and revalve would cost $7-800 and I don't have that kind of cash. Once I get the parts, I'll let you all in on the details.
Off....stings...don't it? I was at 950 with respoking and truing the front wheel. Was worth the cash, but I couldn't get any details on the dark art from my guys wife....who is the office manager.
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Old 03-12-2013, 02:06 PM   #141
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Oh yeah, I just remembered a couple more important tips that Kelvin gave me (I spoke with him for 45minutes AFTER his shop closed). Our old, damper rod forks are usually tuned by changing oil weight. This does not apply to valved forks like WP, and the 4860s especially are often filled with too high of viscosity; it is better to have stronger valves and lighter oil. He uses some sort of synthetic, actually makes his own mixture . He also said that with lighter oil in these forks, they aren't affected by temperature much. He said never go over 5wt, even 2 is fine, or else, you may risk shim deflection issues.

Also, I'm not sure about the 5060s (or 43s), but the air bleed screw in a 4860 isn't big enough to support air cells as well as many other forks. They will work, but with only a 1.5mm opening, not quite as well as they should.
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Old 03-12-2013, 04:51 PM   #142
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Kalvin is a great suspension builder! He built up my WP50s and rebuilt my Ohlins. He really knows his stuff and will talk with you about it. Always been helpful with all my after build questions.
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Old 03-13-2013, 10:03 AM   #143
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Quote:
Originally Posted by naginalf View Post
Ok, I have unsuccessfully contacted several suspension shops who might cater to a DIY rebuild and revalve.
Here's a post I stole from the KTM forum here:

Quote:
Originally Posted by Konflict Motorsports View Post
If you are capable of tearing down the forks, why dont we just send you a kit to revalve the springs with fluid, seals, bushings, and valving stacks?
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Old 03-13-2013, 01:31 PM   #144
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Yup, thanks Solo. Apparently, all the suspension companies decided to finally return my emails at once yesterday . Most of them were not willing to send me valves at all, for "quality control" reasons among others. Konflict and CSR are the only ones willing to help. Bless them for being so gracious, I understand other's reservations.

I just got word back from Konflict, quite promptly too. He did graciously offer his secrets, free of charge no less, and offered to help me out with all the parts including valves. However, he swore me to secrecy if so . Unfortunately, I've already started with CSR, who're much closer to my locale. Please, hit up Alex at Konflict if you're in that vicinity.
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Old 03-13-2013, 01:38 PM   #145
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Originally Posted by naginalf View Post
Yup, thanks Solo. Apparently, all the suspension companies decided to finally return my emails at once yesterday . Most of them were not willing to send me valves at all, for "quality control" reasons among others. Konflict and CSR are the only ones willing to help. Bless them for being so gracious, I understand other's reservations.
whats the going rate in the US to get one of these guys to do a turn-key job on your forks?
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Old 03-13-2013, 01:46 PM   #146
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If you don't need bushings and aren't lowering, the cost is much less. Otherwise, with everything rebuilt and revalved with new springs, I've been quoted $6-800 US, but that includes lowering costs. A simple revalve is only about $250/300 I think, and includes full service but not parts, shims alone can reach as much as $100, springs will be another $110-130. Several companies list their pricing on their websites.

If doing things yourself and are frugal, it pays to shop around a little bit (although if they're helping you with valving, perhaps not). I was quoted $132 just for the stock WP bushings. But if you go to Slavens for instance, he has better bushings for less than $60.
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Old 03-13-2013, 05:24 PM   #147
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I thought we could lower these by making a spacer? I've got no experience with these forks but I thought I'd heard that. Does the tube need to be cut to lower it?
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Old 03-13-2013, 05:39 PM   #148
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I thought we could lower these by making a spacer? I've got no experience with these forks but I thought I'd heard that. Does the tube need to be cut to lower it?
No need to cut the tube you can just put a spacer on the piston rod in the cartridge.

Some people lower the front by putting the forks through the triples but don't measure the travel between the tire or low fender and the bottom triple...
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Old 03-13-2013, 06:43 PM   #149
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Had me worried there. The ease of height adjustment is why I'm getting this fork. I'd like to get a ST shock and lower the G/S down to street height with a low fender for a street tracker. There are a lot of motard wheels out there for this front end.
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Old 03-14-2013, 08:11 AM   #150
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Some people lower the front by putting the forks through the triples but don't measure the travel between the tire or low fender and the bottom triple...
You can also adjust the bottom out level with a spacer behind the hydraulic stop right? I haven't opened mine up yet to learn it's dark, mysterious secrets. I will this weekend tho .
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