2009 YZ 450F Oil Overflow

[dgk194]

Hoping someone has dealt with this - I have an '09 450F with about 9 hours on it. I have change the oil twice, replacing the filter both times and filling based on the volume spec'd in the manual. Before heading out on my last ride, I noticed a fair amount of oil leaked out of the overflow tube (from the cylinder head) after it had been sitting for a while. I rode it again, washed it, put it away, the next day I noticed it had leaked out of the overflow again.

Any advice is appreciated!

[grayracer513]

How much is a fair amount?

Review the oil change procedure here:

https://www.thumpertalk.com/forum/showthread.php?t=852961

If you did all of that correctly, then it should not be due to overfilling. But some oil dripping from the breather is inevitable.

[dgk194]

Thanks. It looks to be around 4 oz. It seems to happen after it has been sitting for a while - I noticed it when I came out to my garage the day after I rode.

[dvn]

Did you drain oil from both drain plugs? Sounds like its overfilled.

[washel157]

You cant go wrong with a quart and a half on an oil/filter change. There is also the bleed bolt in the head.

[grayracer513]

You cant go wrong with a quart and a half on an oil/filter change. There is also the bleed bolt in the head.

You put 1.5 quarts in an '06 or later YZ450 and you'll have oil everywhere. They hold a maximum of 1 liter if you change the filter. In fact, the '03-'05 models only held 1.1 L.

[Wfomx463]

could be due to over revving, if u ride way up in rpm and hit revlimiter a lot it will push oil out the breather. doubt it is due to worn pistion rings. my 08 holds 1250cc of oil with filter. perfect everytime.

[grayracer513]

my 08 holds 1250cc of oil with filter. perfect everytime.

It absolutely does not. If you drain the "tank" and the sump and change the filter, it takes exactly 1 liter to fill it.

Read the manual: 1 quart without a filter, 1 liter with a filter. "Total amount" includes the oil that will never drain out of the engine, and you only have to put that much in after a rebuild.

If you overfill an '06-'09 model, it will never really show up on the dip stick. This is because there is no extra space in the feed reservoir for any excess oil, and the overfill gets pushed back to the sump through the external pressure balance line that runs to the right crankcase cover from the "tank".

[dvn]

It absolutely does not. If you drain the "tank" and the sump and change the filter, it takes exactly 1 liter to fill it.

Read the manual: 1 quart without a filter, 1 liter with a filter. "Total amount" includes the oil that will never drain out of the engine, and you only have to put that much in after a rebuild.

If you overfill an '06-'09 model, it will never really show up on the dip stick. This is because there is no extra space in the feed reservoir for any excess oil, and the overfill gets pushed back to the sump through the external pressure balance line that runs to the right crankcase cover from the "tank".

Is there a downside to 100-200cc of extra oil? Just curious.

[grayracer513]

Is there a downside to 100-200cc of extra oil? Just curious.

Yes, if it is enough to cause it to be forced back to the sump, as it is in the Gen 2 450's ('06-'09). When that happens, the oil level in the sump is higher than it's supposed to be, and that can cause the crank to dip into it. That in turn causes the cylinder to be over-oiled, pushing oil past the rings, building carbon in the combustion chamber. There's also a power loss due to the additional drag. The additional oil vapors this produces will increase the oil out the breather, too. Better than running too little oil, certainly, but still not good.

In the steel framed Gen 1 450's, it didn't matter as much, because the space in the frame was the same as the 426, even though the fill amount was less. You could run the level up to as high as 1.6 quarts without forcing it back to the sump.

[Riding3]

Good explaination Gray, Now for all of the people who always put just a little extra oil in just to be safe? Are we wondering how much oil really is in the bike as we speak?

[dgk194]

Thanks everyone, this is helpful information, especially given that I am a recent 2-stroke convert!

I changed the oil and filter per the manual, it is not leaking now. Maybe I did something wrong on the last oil change.

Thanks again!