No oil on dipstick

Hey! I just put a new clutch in my 2006 YZ450F.Replaced the oil filter.Put 1 full liter of Maxima 10-40 in it,started it,idled it for 3-4 minutes,shut it down ,checked the dipstick...nothing.Waited a few more minutes and checked..... nothing. Put 1/4 more liter of oil in it,started it up again,same procedure........nothing on dipstick.Filter is in correctly.Maybe a bad oil pump?Any suggestions????Thanks!

you should be able to tell if there is proper oil circulation by loosening the dip stick while the bike is running. Oil should bubble out. If it doesn't the oil is not circulating properly.

I checked the oil pressure by loosening the check bolt and oil almost immediately came out. I'll check the dipstick thing tomorrow.

What might be blocked if oil is not getting to the dipstick area?

I had the same crap on my 06. Could not find the problem. I drained oil back out and checked oil filter (SS) and put back in. No oil on stick. Got pissed and rode it anyway for over 30 hours. Finally took off the stater side cases and found hole about the size of a dime under the balancer shaft( went to oil tank). Found the peice. Took it out and have put over 75 more hours on it. Factory is dry sump, now I have a wet sump. Oil pumps out my inspection hole also. Have spoken to 3 other people that have had the same thing. The case is VERY thin in there.

If you have oil at the check bolt, you must necessarily have feed oil pressure, which means you must also have some oil in the reservoir in the front of the crankcase. If you get oil leaking out around the dipstick when you loosen it with the engine running, then you have return oil, too. At that point, one of two things is wrong:

Either the pressure balance vent line that runs from the right crankcase cover to the oil "tank" are is blocked, pinched, or obstructed, or you have the same problem that mx369 details.

BTW, mx, I would fix that by hammering out a small piece of aluminum sheet to fit over the hole. Drill and tap two or three very small holes to anchor it. Clean and rough up the surfaces and apply some Loctite Epoxy Weld Bonding Compound, ans screw it together. Over coat the screw heads to seal them and prevent their loosening. Or get something welded over it. Not good to run it like that.

Thanks guys.After reading your posts I saw your older ones and read them too.It's alot for me to comprehend,but I'll try to figure it out step by step.As soon as I get this problem taken care of I'm gonna sell this bike and get a YZ250 2 stroke.I bought a Yz125 a few months back(my son doesn't like me riding his!) that I have more fun on than my 450,but I'm a large(fat) guy,so I'd like to have more power at times.Although part of the reason my 125 is so fun is it's lack of power(so to speak).Even though I've only been back on a dirtbike for 2 1/2 years after 28 years off,I've come to find that I still like the light weight,powerband hit,freewheeling feel of a 2 stroke.Way less moving parts,less expensive,and easier to work on is a bonus too.I feel like a mechanical genius working on our two YZ125's!Thanks again for the help,guys.

Still working on this.....removed dipstick while bike was running,and it had a ton of air pressure coming out and oil coming out in a very light mist.Should oil be pumping out of there and making a huge mess?Cos' it's not.Just a fine mist.I'm gonna go check the vent hose frome the tank to the clutch cover side.There is also alot of air coming out of the valve cover vent hose,which I think is a good thing and means it's not blocked,right?

The oil that is pumped to the "tank" adjacent to the dipstick is from the return pump. This picks up oil at the sump screen, then pumps it through a passage built into the left crankcase cover (see the picture). By design, the return pump outruns the feed pump so that it keeps the sump "dry". That means that after the engine runs for a minute or so, most of the oil is sucked up off the sump floor, and after that the return oil will be an intermittent, rather than steady stream. If you loosen the dipstick just after an oil change, or just after starting a bike that has not been run in a couple of days, the return stream would be steady at first, then break up as the sump is dried out.

The pressure and mist suggests that you may indeed have the same hole in the casting problem as mx369 did. If you can get that kind of crankcase pressure/pulsation out of the dip stick hole with the vent line disconnected at the tank, I would say it was very likely. Remove the left crankcase cover (flywheel cover) and look for a hole in the area around the balancer shaft.


Okay...hose from tank to clutch case seems very clear and there was a good amount of air coming out of the dip stick hole and the opening where the hose attached.I am going to remove the flywheel cover.I have not yet drained the oil to do this,is this okay?

Assuming it has the suspected condition, you will want it laid over at least at a 45 degree angle to remove the cover in order to avoid dumping a bunch of oil out.

Okay....ooops,dumped out a ton of oil.Maybe all of it. No hole anywhere around that shaft or anywhere inside case.I did,however,find a small piece of metal sitting inside the Rotor.Almost as big around as a toothpick and about 1/8" to 5/32" long.And also a very small other little chunk.It definitely has a sheared or broken look to it.Could this be the Woodruff Key?What next,Grayracer?

Pull the flywheel and check, or post a picture so we can take a look.

My friend said it wouldn't even kick over or start if it was the key that was sheared off.Does this sound correct?Because it kicks over and starts just fine.

Wouldn't run.

If the dipstick is screwed in, can you blow air through the vent fitting on the tank and into the crankcase fairly freely?

how would I do that?

By the way...the little piece of metal is magnetic. ...............The vent holes and tube all seemed to be clear before I took the oil out and the cover off.No obstructions in any of the holes,either.

how would I do that?

Connect a hose to it and blow, if you don't have a compressor.

Okay....Yes,I can blow through it very easily.All passageways are clear. Did you say that if the hose from the tank to the clutch cover is pinched a bit,my dipstick might not read at all? I did notice it is kind of tight coming over and around the case into the clutch case. verify checking the check bolt...I started up my bike and immediately loosened the check bolt.Within seconds it was dripping oil.I saw something earlier about holding the kill switch,but that isn't what my manual describes to do. So...I've put it all back together,filled it with oil and it's still not reading.My local Yamaha shop said just keep filling it,up to 1 1/2 liters and keep checking it.I'll start on it again tomorrow evening after work.........I'm kinda done for the night.Thanks!

Okay....Yes,I can blow through it very easily.All passageways are clear.
You say, to be clear, that with the drain plug in, you can screw the dip stick in place, and blow air into the vent fitting on the tank freely?

You should not be able to do that. That would indicate a leak from the tank to the crankcase somewhere.

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