General > Riding Tips & Tricks
Fork Seal Strategy
don46:
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
bigbellybob:
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
don46:
--- Quote from: bigbellybob on November 05, 2010, 04:13:40 AM ---
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
--- End quote ---
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
suicyde:
--- Quote from: Hillclimb#42 on November 05, 2010, 01:28:23 AM --- 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!!!!
--- End quote ---
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.
suicyde:
--- Quote from: don46 on November 05, 2010, 05:38:09 AM ---
--- Quote from: bigbellybob on November 05, 2010, 04:13:40 AM ---
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
--- End quote ---
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
--- End quote ---
Yeah My YZ I run at 100-102mm, I hear the new KX really likes 106mm
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