'02 YZ426F oil change problem

I just changed the oil on my 426. After draining all the oil and replacing the oil filter I went to refill the oil. After 3/4 of a quart the oil began over flowing from the filler tube. I checked the oil level and it was ~4" above the max oil level on the dipstick. I started the bike and the level remained the same. I let the bike sit for a bit and went back to check it. When I checked the dipstick while the bike was off and cold the dipstick was dry. I started the bike and the level rose to ~3" above the max. level on the dipstick. Could this be an air bubble or something? Any thoughts on how to fix it. I don't want to run my bike without adequate lubrication and I don't want to take it to the shop if it's an easy fix. I'm new to dirt biking but I love it and really want to go riding tomorrow so any help would be greatly appreciated. Thanks in advance!

Did you drain the oil from the sump and the drain located at the bottom of the frame down tube ? If you didn't this could be why you have not been able to put in as much oil as you were expecting.

Assuming you did, the correct way to check the oil level is to run the motor for 1-2 minutes, turn it off, and then check the level.

Check the maintenance sticky posts, there is a link to an owners manual there. you will find the manual most helpful.

Thanks, yeah, I drained the oil from the frame and bottom bolt, and took off the oil filter cover to change the oil filter, so I'm positive there was no residual oil left in the engine.. My main concern is the huge fluctuation in the level of oil from when the bike is off and when it's running. The past 2 times I changed the oil, I added 1 quart and then started the bike. After I had the bike started I added oil until it was at the correct level on the dipstick. The level would only fluctuate maybe 1/2" - 1" from when the bike was running, to when the bike was off. This time however, it barely got a quart in before it started overflowing, and now the dipstick's dry when the bike's off and ~3" over the max. level on the the dipstick when it's running. I have the PDF of the manual, which I downloaded and used to change the oil. I did it exactly the same way as before but now I ran into this problem. Am I just an idiot? Should I just add oil until it's at the proper level on the dipstick when it's warmed up and turned off? Is it normal for the oil level to be so high on the dipstick when the engine's on (i.e. is it normal for the level to fluctuate so drastically?) and drop dramatically as soon as I shut the engine down? I simply don't want to jack my engine up by running it with too much or too little oil. Thanks again for the quick response!

I have never checked the oil while the engine is running. Is that when it is so high, while it is running? If that is the case just add some more and recheck the proper way as you have already stated....with the engine warm and off and let it sit for a few minutes before checking. I have an 02 WR but which is basically the same engine and mine takes over 1.5 qts

Don't check the oil level with the engine running.

Run the engine for 1-2 minutes and shut it off. Then check the oil level.

The reason the oil level 'appears' to fluctuate is the engine runs a dry sump system. When the bike is sitting for a while the oil will drain (in part) back into the bottom of the cases. When the engine starts and runs for a short time the oil in the cases is picked up and circulated in the lube system.

By running the engine a short time and the turning it off to check the oil, you get a measure of the operating oil level.

I had an '03 YZ450 that I could never get a consistant level on the oil, even when done exactly by the book. It still overflows anytime I pull the dipstick out of the frame. I finally just started changing the oil very often and put in the recommended amount (as stated in the service manual) and tried not to worry about it. It hasn't blown seals or crank brgs or valve train parts so I guess its ok. A good friend of mine is the head mechanic at a local shop and said some of them behaved that way when he was setting them up out of the crate, and he didn't understand why either. Dig that old two stroke Ratio-Rite out and put the exact amount in and change it more often if you can't figure out any other way.

I wasn't there, so it may seem odd for me to argue this point, but you clearly did not drain the oil from the frame this particular time if 3/4 quart made it over flow from the top of the filler.

Drain the frame, drain the crankcase, change the filter, and it will take 1.6L of oil to bring it to the correct level every time.

The oil level will appear high while it's running because the return oil flows over the dip stick as it returns from the crankcase. Oil must be checked after running the engine for 60 seconds, shutting it off, cleaning the dip stick, and inserting it without threading it into the filler.

The oil level will show low or no oil if the engine sits longer than as little as 30 minutes due to oil draining past the oil pump from the tank.



Thanks a lot for all the responses. This website is a great resource and I'm glad that I found it. As for the issue I was having, I started the bike, ran it for 2 minutes, shut it off, and checked the oil. The dipstick was still dry so I added about 1/2 a quart and it's now at the correct level. Still not sure why it started overflowing initially cause I did drain all of the oil (Frame, engine, filter compartment) but whatever the reason was, it seems to have resolved itself. Thanks again guys, I really appreciate it.

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