oil spraying from silencer

04 yz 250

last season I really sunk the bike in a deep mudhole, cleaned up the bike got it running but there was oil spraying from the silencer; so I thought it would be a good time to tear down the top end and have a look.

Just finished doing the top end, repacked the silencer yet I stil have oil misting from the silence. I am concerend that this may be a blown crank seal. Any thoughts or confirmations would be helpful.

How difficult is it to replace a crank seal? does the motor have to be removed from the bike, I youtubed this but couldn't find anything.

The wet side crank seal can be accessed by removing the clutch and basket.

Here's what I would do. Change your gear oil, when you refill it, be as precise as possibly and measure out 750ml (don't trust the marks on the bottle). Ride it for while, then drain and measure the oil that comes out. It should be pretty close to the same.

Its easy as pie, remove clutch, remove basket, replace seal. You can do it with the bike laying on its side, you dont need to remove the motor.

To remove the clutch basket is it necessary to have a clutch holding tool, or is there another way? thanks!

Its not necessary but it makes it a heck of a lot easier.

I do it with an impact driver and put a towel between basket and boss, works always.

But with out the impact driver it could be difficult.



Clutch holding tool is a necessity for me. It allows you to remove the clutch and remove the bolt in the end of the crankshaft by holding the flywheel.

As someone said before, find out if it is actually trans fluid blowing from your pipe, not premix oil.

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