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Wheelies leaking a lot of oil in the airbox

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I did a minute and a half wheelie up a hill, getting past balance point, and at the top, the bike died. It couldn't idle and was exhausting smoke when revved. My airbox was dripping oil from that rubber one way valve at the bottom. It shat a surprising amount of oil when I pulled the valve off. The same happened yesterday on a smaller scale, so I had oil with me. I let the airbox drain and topped it off, checking the oil level on the way home. Pulled into the garage with oil at the top of the acceptable level on the dipstick, and only residual oil leaked out on the way home. No worries, this was almost exactly at oil change time.

So first thing's first, I need to clean: air filter, airbox, and airboot. And wash the bike due to all the oil getting flung around by the rear tire. Anything else to clean? Maybe remove the breather box and drain that too?

Secondly, how do I prevent oil loss like this in the future? I don't want to stop doing 12 o'clocks, and I don't see why I should have to. My friends with DRZs can go higher than me, and while they said they sometimes find a small amount of oil in the airbox, but never had it drip out the valve.

I don't want to add a catch can, I want all my oil to stay in the engine. This thread on supermotojunkie mentions running the hose to the breather box from the engine up higher, but the pics are dead. http://supermotojunkie.com/showthread.php?115626-Got-oil-everywhere-Wheelie

I know there's some spongy stuff in the box too. Mine is 11 years old, idk if that shit goes bad. Should I get a newer box?

2017-05-01 19.02.05.jpg

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i'd say just be sure your not over-filing it, its a dry sump and doesnt need to be topped up every other day .. and im imagine you could actually get a ~3' piece of hose and route it up high to the front of the tank from the breather box and then down to the air boot ...

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Definitely not overfilling. I check level the weekly and rarely add any. 

I'll look for some hose. I was just at the hardware store getting hose for my pipe slider. Didn't see any like this. Anyone know a good place to find this stuff? 

Edited by HansLanda

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Did you check the tank for blockage?

I don't ride mile long wheelies but I had the same issue when I eliminated the oil tank. I don't notice the issue with the tank back on. My wheelies only consist of riding it thru the gears, quarter mile or a little better max. I don't do them repeatedly either.

Did you look online at industrial suppy stores such as McMaster Carr or Grainger for hose?


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@ohiodrz400sm No, haven't touched it yet. But I took a look at the hoses and wanted to be sure which one we're talking about extending here. Is it part 9, 10, or 16? I believe it's 10.

Here's an airbox pic to illustrate the amount of oil that got inside. A surprising amount. I'll take the hose with me to a few different hardware stores tomorrow, if I can't find some hose there, I'll get the measurements and look online.

2017-05-02 17.28.12.jpg

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I would lengthen the hose from the box to the air boot. If you lengthen 10, I would think the engine will still be able to push the oil to the box. Once it's in the box the path of least resistance is to the air box while vertical.

You could use the E model FCR bell adapter, air boot, and run 16 up under the tank with a filter on the end.



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Forgot to attach parts pic. I took a look last night and assumed 10 was the one to modify. And it wouldn't be too hard, both ends of the hose are accessible with decent room to work with. 16 However is in a very tight spot. Seems like unless I use a 90° fitting on the box pointing toward the cylinder, it will be hard to route this toward the front. Screenshot_1.png.d86d27c20d64ffe4caad92f7112acd16.png

For the secondary filter option, what would this accomplish? Just being able to zip tie the vent line up high anywhere? How high is high enough? Also still not sure where to route the thing. People say 'under the tank' but with a 3.9 gal, there's not a ton of room. I could probably zip one of these at that open triangle in the frame south of the dipstick.

P1030016.jpg.74ba1abd774f75882a8196cb1d08fd28.jpg

Edited by HansLanda

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Leave 9 and 10 alone. The one you need to mess with is the one attached to the airbox. 

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Ok I found the hose at O'Rileys, got 4', ended up cutting it down 10.5". The OD is 5/8", and ID is 3/8".

With the FCR and Clarke 3.9 it's a very tight fit, and there are not a lot of routing options. I ended up going under the airboot where it meets the carb. Then up to the triangle in the frame, and back down to how it originally routes to the airboot.

Went for a rip and it acted normally. Did some wheelies and didn't notice anything in the airbox. But I need to pack some oil and go back to the wheelie hill to pull another long one to really test it.

The first route the hose takes, going under the airboot doesn't sound ideal, since the point of this is to get the hose pointing up. But in a wheelie, this angle will theoretically be less downhill than the stock route. The route up to the triangle will be very uphill for the oil to travel.

Screenshot_2.png.090d5187b73af5d3d13189f8ead06f36.png

Screenshot_1.png.cf0aafc0bed5aaf2547ee95c28ef9a06.png

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6 hours ago, ohiodrz400sm said:

In the 2nd picture, the hose(9) back to the cylinder looks pinched?
Also, your lock nut is loose on the MCCT.

Both problems got fixed before the test ride, don't worry! I had to remove the MCCT and exhaust to get some working space.

Hose 9 had a bend in it before this all started but was not and is not pinched shut. But good eye, if I should shorten the hose just a bit to straighten it out, oil flow back into the engine should improve! I could probably cut a piece off my new hose and fit it without taking the box off again. That box is a bitch to get on and off.

Edited by HansLanda

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Ok I fixed hose 9. It wasn't completely kinked but now it's straighter. Yes, Ohio, I put my exhaust back on! XD

590be615bb826_2017-05-0417_51_53.jpg.8f050afaf5e5d919e2c495edb6679db8.jpg

Did a 10 mile ride to get to the wheelie hill - some 70mph freeway, and some small wheelies. Checked oil level at the bottom of the hill and it was at the top of the acceptable range (yes, I'm checking the right way - cool down 3 mins, then dipstick without screwing in).

Did a wheelie, shorter than last one. Same result. I let the airbox drain, and checked the oil level - bottom of the acceptable range. I topped it off and went home. Checked oil level at home and it was at the same spot.

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I know my oil's quite black, I did say this was at oil change time. 

Edited by HansLanda

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So what next? I guess confirm that the breather box can actually separate oil? I can pour some oil into hose 10 (hose from valve cover to box) and open up hose 9 to see if it actually can pass through.

What else can I do besides finding a more uphill route? This would be difficult to do with the limited space possibly even with 90° fittings. 

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Hypothetically speaking, what would be the worst case that would could happen if hose 10 just connects back to the cylinder? Too much pressure in the cylinder and head and pop a gasket? I guess I don't understand this engine's oil system and get why this is necessary, all the oil should just stay the engine.

Edited by HansLanda

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Have you ever heard the DRZ run with only the header? Makes the MRD sound like a stock CRF50.

If you got the E model bell adapter and air boot you could eliminate the possibility of oil going into the intake entirely.

Measure what's actually comes out when you change the oil.

Don't connect the breathers. I did that to a pitbike once. Lucky the running problems began before any seals let go.

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1 hour ago, ohiodrz400sm said:

If you got the E model bell adapter and air boot you could eliminate the possibility of oil going into the intake entirely.

Not a real fix though. The E hose goes to the ground instead of the airbox. This would only stop oil from getting in the airboot, but I would still lose oil.

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Not a real fix though. The E hose goes to the ground instead of the airbox. This would only stop oil from getting in the airboot, but I would still lose oil.


You could route it anywhere. If it is still pushing oil out and you have it routed under the fuel tank then you have an issue.

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30 minutes ago, ohiodrz400sm said:

You could route it anywhere. If it is still pushing oil out and you have it routed under the fuel tank then you have an issue.

Yes, I do. So I'm hoping maybe the box simply doesn't let oil exit back to the cylinder, and I could just buy another box. But I know it's a long shot.

27 minutes ago, ohiodrz400sm said:

How long time wise are your wheelies?

Test 1 was 90 sec, very vertical. Test 2 (with new hose routing) was about 45 seconds, very vertical. About the same result. 

 

 

Edited by HansLanda

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