KX Riders
General => Riding Tips & Tricks => Topic started by: Hillclimb#42 on October 19, 2010, 04:04:40 AM
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I have to see what you guys are doing to preserve fork seals and their lifespan. I have never been the guy that jumps the highest or lands the hardest, but it is frustrating to have a good day of riding and then to realize that a fork is leaking. Its downright expensive to blow both sides in a ride. I rarely have a shock problem, but too often am replacing seals. I'll start with what I do, and maybe you guys can pitch in some different things, to get a bigger picture for everyone.
First, I replace bushings in a set of forks that leak in one ride or without cause.
Second, I use a 2x4 between front tire and underneath side of front fender during transportation. That way the strap is not pulling down on the forks.
Third, I make sure both sides are adjusted to the same settings.
4th, I occasionally bleed off the pressure with the fork vents.
Mabe something I am doing wrong, in theory, is only redoing a side that is leaking, which may cause a slight embalance.
Is there any thing I can do doing a fork rebuild to help the life span? Does anyone use a lubricant other than fork oil to lube the tubes? Do you pull the dust covers after every cleaning and remove debris? Any favorite brands of seals? Does thinner oil with stiff settings, or thich oil with soft settings make a difference?
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I have seen a shock type dust protector for the shock on some bikes, maybe that would help at the back? Like a big shock sock.Do you use a power washer near the seals? These can play havoc with seals, bearings etc.
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42,
What fork oil level are you running?
DoldGuy
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Having 5 to deal with, I always run right in the middle of recommended levels. i always ran 7wt in Bel Ray oil, but now am using Lucas oil. It comes in 5, 10, 15, so I went with the 10. I bounce around with different seal brands. i have noticed some have a spring deal that wraps the dust seal and others that have no spring. Would a higher level or lower level help. I am confused, if more oil would be more cushion against bottoming or would be more internal pressure?
kwakman, I have only had one rear shock leak, ever, and it was starting the 500 of all ways to blow it. I do use a power washer to clean them. You think some kind of protector for washing? I was thinking maybe mud dries inbetween the dust seal and oil seal, then the first bump you hit, you have a hard crispy chunk that sticks in the oil seal.
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42,
For the very short amount of time that you run the "Air" in the chamber would not have time to heat up & expand to pose a problem if you are bleeding them every other run or so. It sounds as you already know the basics but just in case: New Dust Seals, No nicks in the sliders (Chrome Tubes), both Fork Bushings in good shape, Springs correct for your weight, Fork Oil Level (amount down from the top of the tubes collapsed) correct? Years ago I had the same problems with my KX with 43mm Tubes, the cures for me was I stepped up the spring rate & lowered the fork oil level (more room for the air before it pops a seal) replaced the cartridge rod bushing (if this is worn the bottoming cone is ineffective) & probably the most important part was I cleaned the Sliders before EVERY ride. A buddy that does suspension work also recommended the Honda seals :-P also because he felt they had better QC than Y, K, or S and he had better luck & would always use them. I also power washed my bike after each practice & every moto & would slide down the dust seal and clean, reinstall with a little bit of grease to capture anything that got in.
Hope some of this might help! :-D
DoldGuy
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Have you used a seal saver? I've had my forks leak without any problems other than dirt getting in there. Put a "Seal Mate" up in there and run it around, may stop leaking without having to replace anything.
Maybe this isnt your answer, but its saved me more than once for not having to replace seals that were still good.
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roostdaddy, i have herd of seal savers but never seen one or one for sale. where can they be purchased
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http://www.motionpro.com/motorcycle/partno/08-0356/
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Keep in mind that most fork seal leaks are due to dirt in the seal, unless a fork seal is dry and hardened, it can usually be cleaned by pulling down the wiper (the first seal you see) and sliding a goggle tear off between the seal and the fork leg clearing out the dust or dirt.
Your air spring should be set to atmospheric pressure every ride. unscrew the bleeder when your forks are still cold to let air out or in. It makes a huge difference. 5mm of fork oil makes a huge difference too, it can be felt throughout the stroke. Its a great tuning tool.
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42,
For the very short amount of time that you run
I do play ride the 250, which is the leaker. :lol: Yeah, you are always very helpful, how do you order the honda seals? Which omodels interchange? No other brand preferences? It has stock springs and I'm about 165. I doubt it's a spring deal, but maybe.
I have used some 35mm film negatives that have worked as the "seal saver", or a laminated business card. its hit or miss it seems, but I will try again.
5mm of oil makes a big diff? Then, I wonder, if its important to inspect fork oil level even when I get the seal cleared of dirt. Once it has leaked during the ride, on the trailor then in the garage waiting on me to get parts, there's no tellin' how much has been lost.
So, if I add a step during the bike wash, I should be good? That being: Pull the dust cover down, clean and lube oil seal.
We used to use Pledge on the rods of the Foosball game that made them spin fast. I have also used Silicone spray lube that seems to work well. Would there be something like that, which might make the inner tube super slick?
The only thing visually wrong, is that there is some oxidation on the small inner rod. I don't think that would have an affect on the seals. I am just sick of fixing them. Its not like I am racing super cross on it. Know what I mean?
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small nicks or scratches on the inner fork tube will make it impossible to keep seals from leaking. its also very common to nick the seal during installation. i use that food rap stuff the wife has in the kitchen and rap the fork tube and bushing before sliding the seal over it to prevent damaging the seal.
i have had great results with these seals.
http://www.synergyseals.com/ (http://www.synergyseals.com/)
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Kyle,
I'm going to throw in my .02.
I've seen countless fork seals leak due to mis alignment, what do I mean? If your axle does not slide into the forks easily you can force the fork to one side causing side load on the seal. anybody that has to use a hammer to get the axle in has issue. I keep my axle and the fork super clean and have made a tool that fits in the end of the axle so I can rotate the axle in without binding the fork. I'm not a proponent of the "take it off the stand and bounce on it theory" and while it may be better doing it than not, remember
Cleanliness is next to godliness, take the time and make sure the axle moves through the forks freely, grease it up and twist it in, and your golden. Motion Pro makes a axle alignment tool, I have one but really have only used it for demonstration purposes to show people what i mean by alignment.
I usually change oil on the race bikes frequently, and the play bikes at least once per year and always new seals, invariably if you don't replace the seals and just change oil the fork seal will leak and you've wasted the high dollar fork oil.
On another issue, and how I think your riding your bike, I wouldn't go over 5 wt oil, I use alot of 2.5 and a fork oil by reline called "like water".
http://www.motionpro.com/motorcycle/partno/08-0412/
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Once I have dissmantled a set of mx forks and cleaned them ready for assembly I always rub the fork legs with wet very fine emory paper Not in a up and down direction but around the tube direction and this cleans and removes any slight nics or smooths out any nicks which causes seal failure. You see a very fine haze affect on the chrome of the forks. I do not rub for ages and ages just enough to clean and smooth any nics thats been put there by racing with other bikes. And its a very fine emory cloth thats wet with oil. To be honest I have used the same piece for a while now that only used for this purpose. Its about 20mm wide and 200mm long and I loop it around the leg so when you hold the 2 ends and work it, Its all around the fork leg. Doing it this way the very fine scratches are in the same direction as the fork seals so it does not leak but it hold oil that is wiped by the seal and it lubes the seal also. If you do it in the other direction up and down the fork leg the same direction the way the forks move you will just damage the forks and they will leak!!. I am not saying this is the correct thing to do but it works for me and the many other bikes I have done.
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One thing I find blows seals that no one has touched Is your fork springs and comp settings. If your springs are to soft for your body weight and or your setting are to soft you will be pleauged by blown seals.
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Don, I always unscrew the axle from the fork and screw it back in. I keep the axle very clean and greased, and it slides right in without a hammer. I have wondered if my 2x4 between the tire and underside of the fender that I am using to help tie down the bikes without the stress being put onto the forks, might be causing stress or misalignment of the seals during transportation. Do you use something like that?
Brian, it was mentioned that stiffer springs and lighter oil might do the trick, but it's all stock and should be the right rate for me. I make sure that the fork doesn't bottom out by keeping an eye on the fork tube during breaks. I usually have 6-8" of travel not being used.
Bob, I use electrical tape or duct tape to fill the bushing groove, so the seal is not hanging up on on the sharp edges. I'll check those seals out.
Thanks for everyone's input...just trying to be thorough
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I have never used anything between my tire and fender during transport. I think that is a myth and there is no way that would stress the forks more then me ridding the bike. The only thing that has ever caused me to blow fork seals premature is the wrong set up.
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many times you dont need to buy all new seals. just run a tear off around the inside of the seal to dislodge any dirt lifitng the seal up. If seen that work fairly well, although it will not help if the seal is damaged or your lower fork tube has a bur that is tearing the seal.
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Ok, bought a seal saver. Basically, a waste of money. Well, it did fix 2 bikes before getting ruined. Its too flimsy and folds easily with pressure. I did manage to make my own out of some clear plastic packaging, which is similar to the tear-off plastic that was mentioned.
I could not fix the 250's forks with the seal saver method. I did get them to slow the leaking waaay down after removing them from the bike, leading me to believe that I had them tweeked in the clamps. I crash alot, and knew I was ridin with tweeked bars, but hadn't considered the forks out of alignment, until Don's suggestion hit me later. What is the best way to ensure the forks are aligned? After looking at it and thinking alot about it, I can only guess that having both forks loose and start with the wheel and axle, and work up the the clamps. Am I thinking right?
I think you are also right about the lighter 5wt oil being better. 10w is pretty stiff. Adjustments are almost all the way soft to be in my liking. I see that stonger springs and lighter oil could be a solution. Does thicker oil or thinner oil cause more or less pressure on the seals? Does bottoming out or stiff setting cause more pressure? Just trying to understand what's going on, not really looking to set-up suspension solely on seal problems. Thanks for your input as always.
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you dont what your susp. to buttom out all the time, it works better when its set up for your weight and riding style.
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First off, the weight of the oil should no impact on seal failure, bottoming out repeatedly will have some effect, not necessarily because of the oil but because you have compressed the air in the fork, the fork extended has a volume of air and lets say it is atmospheric, as you compress the fork it also compress the trapped volume of air and the pressure rises. stiff adjustments will have no affect on the seals other than to say your fork won't bottom as easily and it will minimize the increased pressure in the fork tube. I set my forks up to use the whole travel without harsh bottoming, I do keep the oil changed fairly frequently, have you seen the crap that comes out, and when I do change oil I also change seals and break the fork all the way down and clean everything.
Alignment is important, if the forks are twisted in the clamps, not only does it not handle right it also does not load the fork seal evenly and can lead to premature failure.
On the K5 you unscrew the axle so not much chance of misalignment there, but on the 250 the axle goes throught the lower fork tube with a nut on the opposite side and then 4 pinch bolts this is where I've seen issues, axle gets dirty and doesn't want to go in so they use the cresent wrench to tap it in, this cause a burr on the end of the axle then as you tighten it it pulls the fork tube over causing a side load on the seal. If you have a rider that is sensitive to fork settings they can feel the bit of drag on the fork becasue of the misalignment, I can't feel the difference but have realized the importance of having everything right.
The last thing I will say is that the newer forks seem to leak easier than the older units, the fork manuf. have made bigger and bigger fork tubes and have reduced the surface area of the seal to reduce friction which could leak to premature failure.
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every fork is different. i had the 50mm zoks in 97 and they sucked. second ride on a new bike and the seals started leaking. nothing helped the seals leaked almost instantly after rebuilds. i have some 50mm wp's that r very similar to the zoks and they have never leaked.
and not to get into another ATF debate but, i have used ATF in my forks for 10 years now.
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and not to get into another ATF debate but, i have used ATF in my forks for 10 years now.
:lol: That stuff must be good in everything :lol: SCARY, man. Where'd ya hear about that?
Thanks for the info, Don. Thats pretty much my set-up. I look at the forks after riding a bit, and am looking for just a few inches that have not been wiped clean. Got the seals replaced and am hoping to have that behind me for awhile. gonna try to keep them clean, and aligned. That alignment tool deal is funky to me. I looked at a buddies and it seems that you'd have to hold it on the forks up high, then down low, but you'd have to remove the wheel. I'm a carpenter, by trade, but can't seem to find a solid way to measure their alignment with or without a special tool. I pulled the fender and tried getting everything straight looking. I swear, I work on them just as many hours as I get to ride them. Getting things right means riding with confidence. Thanks for the help...
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Hey HC,
The first time I was aware of the ATF in the forks, it was actually recommended in my Honda FSM for my '85 Cr500 & XR600.
The first time I changed the fluid in them both I used syn atf. (Got lots of junk out of both sets)
Then went to 7wt. fork fluid. It worked just fine. But I'm an old and slow trail rider!
Tuck\o/
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That seems weird to me. ATF in the forks, a little cheaper, but how would you know what weight you are using, or be sure that its performing right. Foaming or expansion and contraction with atmospheric changes and riding conditions. It would be hard to tell what's goin on inside there, and its expensive parts to replace, if there is an issue. I'm no expert, not even close, is it the same chemical composition? Does the vicosity of ATF, and the oil that's typically used, react the same to extreme temperature swings? Is the FSM like "Factory Support Manual" or something like that, Tuck? Not stoking a debate, just interested in everyone's opinion, to get a good working knowledge of these forks.
Its also weird that when you dump out the old oil, it looks like used crancase oil or somethin'. What causes it to darken like that? It has to be internal oxidation of parts, don't it? Surely thats not all dirt and grime that passes by the seals. :?
What does it do, if you run a higher oil level than standard, or lower? Does it translate into harder/softer or is it just a recommended window of oil capacity levels? Suicyde?
What is the best method for oil level? Measuring down form the top of the compressed fork, or ratio cup with the recommended amout of ml's? I have been doing both as a double check for my rookie status, but all of the double checking adds to the repair time quite a bit. Thanks for all of the responses, hopefully I am not the only one that needs the education!!!!
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Its not just the fact that your bottoming out that kills the seals, It's the speed at wich it happens. The forks blast through their travel way faster then they would other wise and the pressure in the forks spikes very fast and very high. Also in my opinion you should use the fork oil that comes in the bike stock. back in the day forks were not adjustable to the degree that they are now so you would have to change the weight of the oil. Now most forks can be adjusted way to soft or stiff by the clickers alone thus making it pointless to change the weight of the oil. In most cases that I have seen people just create head aches by putting the wrong weight oil in their forks.
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I agree with Brian it's not the bottoming its the speed at which you bottom that cause problems. I'ved used ATF in forks in the past but probably not for over 20 years, I use either Golden Spectro or Red line fork oil. The golden Spectro is 5wt the redline I have is from 1.75wt all the way to 7wt, and depending on the application depends on the weight of the oil as a rule I would stick to 5wt for the kyb's. On your fork cartridge the is an anti bottoming cone, thats the little silver piece that spins on the cartridge rod, if mates to a tube and together they are the anti bottoming device. A higher oil level has more resistence to bottoming, a lower level conversely has less resistance to bottoming. There are boatloads of parts and fixes for the KYB forks, some work and some don't, many of the later model forks had an oring on the mid valve, replacing that with a spring was a big improvement. They also came with bladders on the fork, many tuners removed them and some didn't.
If you have the ability to revalve your forks you should take the time to get it setup for you, if you don't find a good suspension shop that you can trust. From my experience I would stay away from the big names you don't get what you pay for, small shops usually have the guy that owns the shop doing the work, I used to send mine to Tom Morgan, he did a phenominal job. Surely you would have somebody in your area that was equally good. Maybe you all can chime in and let everybody know who does good work and who doesn't
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i was flabbergasted the first time i did the forks on a ktm. the manual only gives you a air space number and doesn't tell you how much oil to put in. its really easy now that i know what to do. i use a peace of hose from my baster with a o-ring over the hose. you slid the o-ring up the hose tell its at the desired number say 120mm from the end of the hose. then you just hold the o-ring at the top of the fork and suck out fluid tell it wont pull any more out and you have left 120mm of air space in the fork. less oil is smother but will bottom easier. to find a happy spot i start on the low side for oil and then inject 5ml at a time through the bleeders tell i get to the sweet spot
and as just throwing the ATF out there it has worked for me but i don't expect anyone to try it based on that.
for the dirty oil coming out its mostly from the bushing wearing.
and IMO the best thing to do when setting up you suspenders it to start with the sag. nothing is going to work right tell you set your sag. i find this to be a good right up on setting it. now if i could just come up with the cash to buy some new springs.
http://www.harrymoto.com/MX/RaceSag/set_your_race_sag.htm (http://www.harrymoto.com/MX/RaceSag/set_your_race_sag.htm)
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and IMO the best thing to do when setting up you suspenders it to start with the sag. nothing is going to work right tell you set your sag. i find this to be a good right up on setting it. now if i could just come up with the cash to buy some new springs.
http://www.harrymoto.com/MX/RaceSag/set_your_race_sag.htm (http://www.harrymoto.com/MX/RaceSag/set_your_race_sag.htm)
Bob is right there are basics to making your suspension working correctly, all suspension bearings must be in good shape, you must have the right springs with the proper sag set, and generally speaking suspensions are set up for 175 lb intermediate riders so if you fall in that realm you might be good to go. on the 06 250 and up to 05 250f I always used a fork oil level tool, set mine at 100mm, the newer stuff is a bit different, there is the cartridge chamber that is filled seperate from the fork outer tube both are typically measured in ML not in mm of oil level. fresh oil is your friend, not just in the forks, the shock as well, have you ever rode your bike hard and felt how hot the reservoir is change it and keep your nitrogen pressure at the desired set point
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What does it do, if you run a higher oil level than standard, or lower? Does it translate into harder/softer or is it just a recommended window of oil capacity levels? Suicyde?
What is the best method for oil level? Measuring down form the top of the compressed fork, or ratio cup with the recommended amout of ml's? I have been doing both as a double check for my rookie status, but all of the double checking adds to the repair time quite a bit. Thanks for all of the responses, hopefully I am not the only one that needs the education!!!!
The fork oil rests on top of the compression shim stack, less oil means a softer initial to mid stroke, more oil, stiffer initial to mid stroke. its a great tuning tool.
most forks from the 90's is measured in mm from the top, with the spring out and at the bottom of the stroke. newer forks like my '09 yz it is a measured amount that is poured in. check your manual for fork oil height and adjustment settings.
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and IMO the best thing to do when setting up you suspenders it to start with the sag. nothing is going to work right tell you set your sag. i find this to be a good right up on setting it. now if i could just come up with the cash to buy some new springs.
http://www.harrymoto.com/MX/RaceSag/set_your_race_sag.htm (http://www.harrymoto.com/MX/RaceSag/set_your_race_sag.htm)
Bob is right there are basics to making your suspension working correctly, all suspension bearings must be in good shape, you must have the right springs with the proper sag set, and generally speaking suspensions are set up for 175 lb intermediate riders so if you fall in that realm you might be good to go. on the 06 250 and up to 05 250f I always used a fork oil level tool, set mine at 100mm, the newer stuff is a bit different, there is the cartridge chamber that is filled seperate from the fork outer tube both are typically measured in ML not in mm of oil level. fresh oil is your friend, not just in the forks, the shock as well, have you ever rode your bike hard and felt how hot the reservoir is change it and keep your nitrogen pressure at the desired set point
Yeah My YZ I run at 100-102mm, I hear the new KX really likes 106mm
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I must be doing something right since in 39 years of dirt riding I have never had an issue with fork seals. Nada, never. Problem is I don't what I am doing right. When I sold my 92 KX500 it still had the original fork seals after 14 years of abusing it - no leaks (actually the KX never leaked a drop of anything ever - pretty darn good, my kids KTM leaks from everywhere). Reading Dons post mad me realize that the one thing that I always do is align the forks before I tighten the front axle. I never put a support between the tire and fender when trailering; I never have cleaned under the seals with film (although that sounds like a great idea); never used forkskins, etc. Anyway....food for thought. It is possible that alignment is one of the keys. As for ATF, I used it for years as fork fluid. My dad used to tell me that type A was 8wt and Type F was 15wt. Not sure if that totally true but it is an easy rhyme to remember. In the old days I used the A in most of my bikes. Presently I use F in the low-end non-cartridge type forks, F in my CBR900RR street bike and A in the high-end non-cartridge forks. In my fancy dual-chamber cartridge forks I am using 5wt fork oil in the inner-chamber and synthetic ATF "A" in the outer chamber for reduced stiction. Works for me. It is also a decent cost saving for those who may have 5 or 6 bikes at home. Cam.
PS the KTM forks leak like hell but they did when we got the bike. Time for a fix this winter.