Fork Oil Change in 99' YZ400

3 replies to this topic
  • horseman3

Posted April 29, 2006 - 03:05 PM


Had some busted seals so i replaced them this afternoon. The shop told me to fill the fork leg back up 130mm from top with fork extended after cartridge had been pumped. As i finished this process the forks seem to me like they are too full of oil because they will travel approx 2 inches before what feels like totally hydrolocking. Im so confused as to what the whole process is now and not sure how much to remove. Any help would be great and thanks.

  • Satch0922

Posted April 29, 2006 - 04:15 PM


with the springs out, forks fully compressed, you should fill each leg to 100mm from the top

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

Posted April 29, 2006 - 04:32 PM


They were wrong if they told you that. Satch is right, fill them with the spring out and fully compressed. If you still don't get full travel out of the forks at 100mm from the top, you can increase the air gap(distance from the top)in 5mm increments. (if you don't already know, you can use a syringe with a hose on it or a turkey baster to suck out the excess oil, just mark the hose with the height you want and line the mark up with the top of the fork leg) If you want to monitor how much travel you're using, jot down how far the forks compress while you're putting oil in, then put a rubber band(or a zip-tie) around the lower fork leg to see how far they compress while you're riding. The air gap, as you found out, acts as a progressive spring inside the forks.

  • One Louder

Posted April 29, 2006 - 05:11 PM


and put on some SealSavers so you won't have to mess with this again! :crazy:

Related Content


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.