Oil Glass problems 2010 YZ450F

the issue with this is that highly airetad oil lacks the proper lubricating properties. It therefore causes accelerated wear. In my opinion, if your having this happen something is wrong


You should be aware that the "highly aerated oil" invariably rises to the top of the oil supply, and that the engine feeds from the bottom.  Thus the oil actually being used by the engine does not generally include any air.  The aeration is in part a natural by product of the fact that the return oil pump outruns the oil incoming to the sump as a part of its design function to keep the sump "dry".  It inevitably slurps air and pumps the resulting foam back on top of the oil in the reservoir, and as pointed out, the oil itself will have a much lower tendency toward foaming when up to temperature. 


It is also true that certain oils have a much greater tendency to foam than others.  Lucas, for example, performs quite poorly in foaming tests compared with many others.  You might try switching brands to see what comes of that. 

Sorry for the late reply. The bike is at another location. I'm thinking I've overfilled the bike.

I've read the manual and noticed it says there is a drain bolt above the window glass. Do I drain only after starting the bike as I would checking the oil? Or do I drain the oil after its been ridden?

I'm sorry for the dumb questions guys. I really am new and I'm trying to learn. I came from the quad world (LTR 450), so yamaha is a brand I haven't dealt with. It just seems odd the situation requires so much knowledge before checking something like the oil. My quad has a dipstick; check and go. Simple

Re-read page 3-9 of your manual a little more carefully.  It says to start and run the engine, shut down, wait a minute, then:


3. Inspect: • Oil level

Make sure that the engine oil level is between the maximum level line "a" and minimum level line "b" shown for the oil level check win- dow.

Above the upper limit "a"Check that no oil comes out when the check bolt "1" for the oil quantity upper limit is removed.

If any engine oil comes out, drain it until its last drop is out.


The bolt is behind the shifter, not above the window, item #1 in the picture.


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