Thinkin about tackling my fork

9 replies to this topic
  • jagarcia89

Posted January 10, 2010 - 10:28 PM


After watchin my seals leak oil for the past 2 rides I'm gonna give it new oil and seals. I am a certified bicycle mechanic and have done many high end mountain bike forks but have never done one on a moto. My questions are

what are the similarities and differences in the two?

What parts and seals should I replace while in there? Any other tips or suggestions?

  • grayracer513

Posted January 10, 2010 - 11:20 PM


Any other tips or suggestions?


You can start by telling us what kind of bike we're working on.

  • CaptainKnobby

Posted January 11, 2010 - 06:41 AM


hopefully it will be a Yamaha :moon:

  • jagarcia89

Posted January 11, 2010 - 09:41 AM


Oh sorry 98 yz400f

  • grayracer513

Posted January 11, 2010 - 09:55 AM


Those are the open bath, or single chamber KYB fork used on all '03 and earlier models. They're pretty simple. The manual goes start to finish through a full tear down, but there generally is no need to remove the base valve or damper cartridges.

Just remove the springs, remove the seal retainer snap rings, and pull the upper tube off the lower by snapping them to full extension sharply, as with a slide hammer.

With such an old bike, you will probably want to replace the bushings (the manual calls them "metals". Don't know why). These just snap in and out of place.

Look for scratches and dings in the inner tube. If found, sand them out with 240 or 320 wet/dry. Invest in a real seal driver ($35-60).

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • buzzfin

Posted January 11, 2010 - 06:39 PM


Watch this video, it will take you through it step by step:

  • matt4x4

Posted January 12, 2010 - 08:48 AM


as Grey said - but no need to invest in a seal driver or a bullet - a well greased decent thickness ziplock bag over the inner when sliding the seals on is all you need to protect the seals from the sharp edges where the bushing sits, and you can make a seal driver from appropriately sized ABS pipe sliced lengthwise - it works perfectly fine.

Only reason I'm saying not to invest in this tool is because it's a 1998 bike, you may not have it THAT much longer and the tool will be useless to you on all newer bikes. Now if you plan on keeping it for forever, buy the tool.

  • jagarcia89

Posted January 12, 2010 - 02:47 PM


yeah the bike is for sale as we speak so I'll pass on the tool. Im sure I can rig something up as Im doing this in my bike shop. Anyone know roughly how much oil I should buy??? I know this is in the manual but i forgot it at home and would like to knock this out today

  • grayracer513

Posted January 12, 2010 - 02:56 PM


You'll need two quarts; it takes just over one to do the job.

  • jagarcia89

Posted January 12, 2010 - 05:06 PM


Thanks guys. And grayracer- you yzdom never ceases to amaze me. I hot the fork done in about 30 minutes. These things are a breeze!

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