09 yz450f front sproket leak

I just put my bike back together after a winter tune up, never touched the front sproket. Never leaked before but as soon as i started her up a low leak started dripping from my front sproket. I did put her on her side so i could open up the clutch. Would that have caused this? Anyone with advice would be awesome. Thanks!!

maybe its time for a new sprocket

Your counter shaft oil seal might be worn and needs replacement.

New seal needed

Remove the sprocket, pop out the old seal and press in a new one. Give everything a thorough clean first. :smirk:

If you have any problems getting it out one trick is to run a small wood screw into the metal part of the seal a little bit so you have something to grab a hold of to pull it out.

Oh, and don't forget to lube the lip of the seal up with some motor oil before you install it.

So got my new seal, tried a few times to get the old seal out with no luck, tried the wood screw idea but couldn't get it to hold, maybe it was to big of a screw, gonna try again tommorrow. Any more tips would be greatful. thanks again guys

Two approaches to take:


  1. Using a punch or screwdriver blade, tap around the edges of the seal, driving it IN a small amount. This will break the bond between the case and seal.
  2. Using a wire hook, machinist's pick, etc., pull the seal out.


  1. Remove the steel collar from the output shaft
  2. Insert a tool under the seal and pry it out

You can often just catch the outer edge with a small screwdriver or knife blade and pluck them out that way.

If the collar doesn't want to slide off:

  1. Tap the output shaft straight in toward the opposite side of the case. This will break the bond between the O-ring on the output shaft and the collar.
  2. With the trans in gear, grab the collar with a pair of pliers and turn it on the shaft as you pull.

  • There is an O-ring on the shaft under the collar. Replace it.
  • The collar may have a groove worn in it by the seal. If so, replace it.
  • Don't install the seal too deeply. Insert it no farther than flush with the case.
  • The undercut side of the sprocket (if it has one) goes IN.

Using your advice got it off and new one on! Works great, get some good riding in this weekend finaly thanks!

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