Gear oil disappearing

[Bz1hx]

Hi All,

Hoping for some insight on this issue. New-to-me 2001 KDX200. Keep in mind I’m only 3-4 rides into ownership. I seem to be going through excessive amounts of 80w-85 gear oil. On Wednesday evening it was full (top of sight glass). Went for about a 2-hour ride on Thursday and it’s now below the bottom of the sight glass. Absolutely no obvious leaks and no excessive exhaust spooge (some drippage down the pipe, but it’s not spewing oil on the fender). Coolant is clean & full. Solution for now is to keep topping it up, but I see splitting the case in my future. Two questions: 1) Am I overlooking a simple fix? 2) Does a comprehensive rebuild kit exist or am I on my own piecing together parts?

[KDXGarage]

Welcome to kdxrider.net.

Are you checking the level with the bike on the kickstand or with the bike in a level, riding position?

[Bz1hx]

Thanks! Glad to be here.

The bike sat on the stand for a several days before riding and oil was checked the day after riding. It sat on the stand overnight after the ride. Checking the oil level on the stand; bike is level.

[KDXGarage]

Is any going out the vent tube?

[Slick_Nick]

Might have a failed crank seal and it's burning it.

[Bz1hx]

Is any going out the vent tube?

Not that I can tell. I would think it would be a massive leak if it were.

[Molly's 70]

If you don't figure it out, a leak down test will help.

[Bz1hx]

If you don't figure it out, a leak down test will help.

Would that help determine if there’s a leak or blown internal seal? Guess I’m not familiar with a leak down test on a 2stroke.

[Molly's 70]

Leak down testing will let you know of any leaks. i.e.. seals, gaskets, basically anything that can leak.
Watch some YT videos.

[Mnolan660r]

I have recently completely rebuilt 2- 98’ 220R’s and a 97’ 200. Some observations that may help guide you in the right direction:
-the case halves are sealed with FIPG, there isn’t an actual gasket. All 3 had failed and transmission oil was getting into the “lower void” below the crank, (not the area where the crank is).
On 2 it was also getting into the crank case lower end, and I assume being burned up.
-on 2 (one of the 220R,s and the 200) it was getting into the flywheel area. This one was a bit of a mystery to me, but I would recommend pulling the plastic side cover and making sure it is bone dry. If there is any “oil” in there, it’s most likely a bad main seal, or possibly transmission oil, like on the other 2.
-on one of the 220R’s (the one that isn’t mine) the owner told me that his still eats transmission oil, like what you have stated. We have had that motor completely torn down 4 times now, with a second set of factory new seals, and 2 different types of FIPG (yamabond and locktite 518) and the problem still persists.
I originally used the locktite 518, and have used it for many builds with no issues. We are not sure that the case halves sealing are the issue, but are at a loss.
Make sure to re-gasket the plastic flywheel cover, and torque to spec- don’t over tighten!!!

Hope in some way this helps.

[Bz1hx]

UPDATE. I have not done anything to the bike other than ride it. Somehow, as if by magic, it’s completely stopped going through gear oil. No loss at all. None. I’m baffled. I suppose the crank seal could have reseated or swelled but I have no idea. Just thought I’d share

[KDXGarage]

Thanks for the follow up. That is a good way for it to happen.