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After my last ride I cleaned my bike up and noticed that I was missing about a 1/2q of oil out of the main case. When we went riding I was at the top of my site glass and later after cleaning and inspecting i noticed i was low. So I figured that i have a leak but found nothing. Checked radiator clean,checked air box clean, checked drain plug it was good, removed magneto cover it was dry. Has anyone had this problem before? My bike is an 04 so I am running out of ideas on what to check.

Fuzzy's old (stolen) KDX used to lose oil... but his leaked it out of the cover I think. I don't think you bike could eat it... could be wrong though.... Others proly know about it than me... What kinda oil are you using?

A bad seal could be the problem. It will sneak past and into the crank area, then burned during combustion. Here's the best way to check: Drain, fill with an exact amount, ride, drain and measure how much you pull out. If some is missing, and there's no external leak, you have a bad main seal. Not cheap!

How did you determine that you were 1/2 quart low?

Sounds like it may be a leaky crank seal. I guess the right could leak and the left not ? The right lets oil into the cylinder. Notice any extra smoke? My '98 was doing the same thing, new seals and bearings fixed it. A '04 seams kinda new for that though.

jason
when he told me about it, i said from the top of the glass to the bottom damn thats about a half a quart. probably where he got that. his bike doesn't smoke excessively and he said he wasnt fouling plugs. i also thought crank seal since there isnt any sign of an external leak but the thing is only a year old. anyway i told him to do what skipro said above just to see exactly how much was missing after a ride.

Are you guys sure the oil didnt just settle through the box and gears etc. Mine does that after an oil change, ie. reads full in the sightglass after filling it then lowers slightly after the engine has been run. Good luck

KAY DEE EXER wrote:Are you guys sure the oil didnt just settle through the box and gears etc. Mine does that after an oil change, ie. reads full in the sightglass after filling it then lowers slightly after the engine has been run. Good luck

That sounds more right.... I can't see how that new of a bike could develop that kinda problem.... but stranger things have happened.

Any chance the freshly used oil didn't have enough time to drip down and setle to a normal level? Any chance the oil level changes when hot compared to when cold??

Yeah, I think everyone is on track here....Need to ride it more to see if oil consumption is steady...

Does it smoke?

Any oil in your air filter box?

Did you bike spend much time upside down?

I was thinking about this today and boy,.....1/2 quart is ALOT of oil to go missing in a single ride. That's more than half the oil recommended to run in there. If the bearing seal was bad, you whould have noticed a drop in performance with the bike.
I noticed today that with just 1/2 quart added to my gearbox, the level is correct in the window. Or course running it, stopping and then checking showed a different story. I wonder if the last oil change was done using the sight glass and not running the bike after to get a good reading?
Most folks agree that a full quart of oil is a good practice with the KDX. The extra oil doesn't harm anythiing, it makes the bike quieter, and it's easy to see that you take out what you put in. I save the plastic oil bottle, then reuse it to drain my oil back into. A funnel is all it takes.

Let us know what you find out.

skipro3 wrote: Most folks agree that a full quart of oil is a good practice with the KDX.

The only problem I'v run into with using a full quart is that with my bike it tends to spit oil out of the overflow and on to my filter. So I pour a little in slosh it around a bit in there then drain and add the rest of the quart.

O.K., I just changed my oil this morning. When refilling, I noted that it took less than 1/2 quart to put the oil level just at the top of the site glass. I suspect that the oil was last filled using the window as the guide instead of by volume of oil. It did seem strange to add 2 times the amount of oil needed to completely fill the window though. I've never used the window other than to look at the condition of the oil since I knew a full quart in the tranny would fill the site glass completely. BTW with the bike running, looking into the site glass, it seems like there isn't much oil in there. It takes about 1/2 hour for the air to settle out after shutting down to have a clear view in there as well.

First I would like to apologize for not responding to everyones replies I have been way too busy even to turn on my computer. I really do appreciate everyone's input on my problem with my bike. I will try to sum up my problem with the missing oil.

1) It was not a result of a fresh oil change this was the second ride on this oil.
2) The bike does not smoke hardly at all yet.
3) I determined that I was 1/2q low because before the ride my oil was at the top of the site glass and when i noticed it low it was at the bottom of the site glass. My bike was cold then and it is garage kept and none was on the floor.

I am going to give a fresh oil change and one good ride a chance to see if it happens again but I am really concerned about damaging the engine more than just having to replace a crank seal. I know that a crank seal job wont be cheap but it will be cheaper than replacing an engine what do you guys think?

Any chance you may be holding the bike at different angles when checking the oil? At the exact same angle, there is not 1/2 quart difference between the top of the sight glass and the bottom.

As long as there is SOME oil in the crank, it won't be damaged. Burning crank oil also won't damage the bike. If the seal on the ignition side leaked then you might suck some air in and have a lean condition but I've never heard of damage from that.
So testing the bike by changing the oil, measuring exactly how much goes in, then how much comes out after an easy ride should be fine.
I'm not sure how much you are willing to take on mechanically, but you can save some cash if you are able to pull the motor out of the bike, tear down the top end, remove the flywheel and the clutch before dropping off at a shop to split the cases and replace the bearing and seals. A good shop can measure all the clearances and such for in spec. on the parts while it's apart too.
I know there's a way to pressure test the crank for leaks but I've never done it. Maybe someone here can enlighten us on that option to confirm a leaky crank?

Thanks for the info skipro3 I will check into the pressure test. As far as checking oil I am on a flat surface in my garage got bike setting straight up and down on a bucket.
I can do some of the break down myself and with the help of my buddy 89kdx200rdr we should be able to figure something out. I will let you all know what we come up with.