2010 YZ450F Oil Leak



New to the forum and 450 dirt bikes. Recently bought a 2010 YZ450F bike and love it. I failed to notice the oil leak when looking the bike over, and I'm wondering if this problem is simple, or needs to be taken to a shop to be torn down. On a scale from 1-10 of my mechanical skills, I'd say I'm a 4. The pic shows the oil leak; looks like the left side crankcase cover. Are these plastic plugs and oil seals, or is this something related to a cracked case and I'm looking at a rebuild? Any help for this newbie would be appreciated. Thanks!


Edited by oneindustree

If you mean its leaking from around that cap its probably just tge o ring behind it

Yeah man, that cap. I looked at the owners manual, I'm not seeing an O-ring behind the cap. I'll prob order the oil plug set and replace it and see what happens. Have you needed to replace these before?

Never had to replace mine. I have an 03 and an 04 yzf and a 79 honda they all have o rings not 100% sure bout your bike though but its gotta seal somehow

These are just plastic caps to be able to see inside at the crank correct? I was worried it was part of the crank case cover and had to be replaced

The center one gives access to turn the the crank so you can use the top one to locate the timing mark.

Hopefully seller didn't represent as 2010. Must be something earlier. Looks very clean.

Definitely not a 2010.  '08, '09 maybe.

I'm just saying but that looks like a stock photo of a new bike.. I'm going to guess that's not the actual bike.. But for sure not a '10 in that picture.

Guys, thanks for the responses. you're correct, the bike shown is another photo on the net. Here's an updated photo of my bike. Is it odd the crankcase cover is black,or did Yamaha build some 2010's with this color?

Jeez guys, sorry still getting used to this site


Edited by oneindustree

Jeez guys, sorry still getting used to this site

Ahhh. Good, I was hoping someone didn't try to scam you. The side cover has been painted black. Inspect the mating surface of the plug O-ring to make sure it's not causing the oil leak.

Well damn. I'll pull it off and sand it down. Drain the oil, take the cover off? Is it that simple?

Well damn. I'll pull it off and sand it down. Drain the oil, take the cover off? Is it that simple?

Pretty much. You could get away with not changing the oil if you tipped the bike over on its side too :D

I'd try some spray paint remover and a power washer first. You may be able to avoid sanding.

Edited by x_JT_x

You guys are awesome. I'll ask my questions about riding tips in the general forum section

No need to drain the oil or remove the cover. The problem is almost certainly damage to the O-ring or dirt under it, or it's just missing. Paint shouldn't be an issue, although there could be a built up dried drop on the seal seat.

If you run the bike for about a minute before you open that up, no significant oil will be lost, since the bike is a dry sump system. Read about that in Common Threads.

Anyone happen to know Allen wrench size for these two plugs?

If I recall the smaller of the two is an 8 Allen,. You should really have a set and test them though

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now