09 yz450f front sproket leak

8 replies to this topic
  • charles_guy91

Posted May 23, 2011 - 04:50 PM


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!!

  • yz450fcranker

Posted May 23, 2011 - 11:31 PM


maybe its time for a new sprocket

  • dirtcrow

Posted May 23, 2011 - 11:39 PM


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

  • jratcliffe3

Posted May 24, 2011 - 12:27 AM


New seal needed

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  • dgcars

Posted May 24, 2011 - 12:53 AM


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

  • RiderX

Posted May 24, 2011 - 05:33 AM


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.

  • charles_guy91

Posted June 06, 2011 - 01:56 PM


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

  • grayracer513

Posted June 06, 2011 - 02:24 PM


Two approaches to take:

  • 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.
  • Using a wire hook, machinist's pick, etc., pull the seal out.

  • Remove the steel collar from the output shaft
  • 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:
  • 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.
  • 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.

  • charles_guy91

Posted June 09, 2011 - 09:54 AM


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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