Help stopping an oil overflow while doing wheelies

Hey, guys. Merry xmas and happy new years!

I'd like some help in figuring out a way to stop my bike from having the engine & transmission oil from overflowing out of the large overflow tube that's located on top of the cylinder head while I'm doing extended wheelies.

I've noticed that after I've done some wheelies my bike leaks oil through that tube, which comes out from the cylinder's top and ends with all the others that exit from the carburator, near the base of the swingarm.

My bike is a 2007 KTM 250sxf.

Any help will be greatly appreciated!


huh. Never heard of that before. I ride my yz for miles on the back tire with no oil leaking. You could try a small filter on the end of it.:busted:

A small filter on the end of it?

I'm sorry, I don't follow... What type of filter? That wouldn't stop the oil from going out of the cylinder and into the tube, though... would it?

No not really,but it might keep the oil from getting under your tire while going down the road. There is no way to really cure your issue since the air pulses are traveling in both directions.

You could try re-routing it so that when your on one wheel the breather hose would be at 90degrees with the ground:thumbsup:

That sounds like a good idea, thanks for the tip, I'll get to it now!

Hey, thanks for the tip, though I'm sad to say it didn't work... now my engine's all coated in oil :busted:... time for a wash.

I'm thinking of plugging the tube with a screw, that'll stop the oil from leaking out. Do you think that will create any problems with too much oil filling up the cylinder?

You cant plug it. Its a breather tube :busted: Besides races arent won by wheelies anyway. Yea there fun, but they chew up your tire's, and in your case Gets oil everywhere.

I think you have another problem. Try posting in the ktm forum:thumbsup:

make the hose longer and have it go up towards the handlebars.

How much oil are you putting in the motor?

hehe... I don't wheelie while racing, that's while I'm out, illegaly riding on the street :busted:...

I'll try that rerouting option again and post in the KTM forums, thanks. I've got about 800ml of oil, I think... I put in what the manual recommends, but since it started leaking I've just added enough to keep the glass eye filled, since after wheelieing for a while it drops to the point that it can't be seen through the eye.


I would get some hose and route it in the other direction. Try routing it around the left side of the motor (above the ignition cover) and then down the front downtube of the frame. This way you still have the proper venting, it still can dump under the bike, and when you are doing extended wheelies the vent end will be higher than the oil level in the cases so it won't run out.

Of course, if you are also into extended stoppies then you will be puking out oil when the bike is standing on its' nose!

Sounds good, I'll do that this afternoon, tell you how it went later.

Thank you!

No stoppies, though... too scared of doing an endo...

Nope... I'm sorry to say, routing the tube up the frame towards the handlebars didn't solve the problem... Still get oil expelled by the compressed gases that pressurize that breather tube. Any other ideas?

Nope... I'm sorry to say, routing the tube up the frame towards the handlebars didn't solve the problem... Still get oil expelled by the compressed gases that pressurize that breather tube. Any other ideas?

Okay, the ultimate solution. Maybe!:thinking:

Route the hose up to a catch can that you can mount somewhere. With the "can" mounted vertically, have the breather hose enter from the side at about the middle. Stuff the can full of coarse foam, and then have the breather hose come back out the top.

The theory is that the oil that is blowing out of the crankcase will hit the foam in the can, and thus kind of capture it, filling up the bottom of the can, with the case still able to breathe out of the top. You will need to drain the can every now and then (maybe more) to get rid of the oil, but it should at least keep it from going everywhere else.

The issue, is where to put the can, and how to route everything. Moroso and some other companies make ready made oil catch cans like this for racing cars. I also ride a turbocharged snowmobile that has this modification done as the high boost pressure causes a lot of oil to be blown out of the motor on occasion.

If you want to attempt this, good luck!

My 525 does it also , I took hose up frame to radiator gaurd and put a small lawnmower " plug in " hose type . Little foam filter in it . Still blows some oil out , if I lay it over in crash :thinking:

Unfortunately, none of these solutions seemed to work for me... I think it might be too much oil, though I believe I had the recommended amount. I'll drain it and add the recommended amount and let anyone still reading this if the problem's solved. Today I rode for a while and the oil overflowing was almost none after doing wheelies.

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