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Airbox Breather Tube (aka OIL LEAK!!!)

61K views 56 replies 28 participants last post by  MPD193 
#1 · (Edited by Moderator)
For those that work on their own bikes or take them to a stealer.

IMPORTANT:
Do not try to block the seal from coming out or you could cause serious damage as it acts like a relief valve.
Here is a copy of a post that I have been posting for at least seven years.
This is about the hose behind the bottom of the airbox.



I do this every time I get my X back from the stealer

If the air-box is ever removed by you or the stealer, there is a possibility the breather hose for the crankcase could get pinched. (This hose is the pressure relief for the crankcase, so pressure dose not build up.)You could have a pinched hose.

If it is pinched, pressure will build up in the crankcase and blow the seal out around the shifter lever.
If this seal is ever blown out, you can put it back in by tapping it back in.
A simple way to check is:
Take the air cleaner cover off.
Take the dipstick out and lay a 3x3 single layer of tissue paper over the opening.
Take a common drinking straw and hold it over the smaller hole in the air-box, (the one that sticks out), and give it a puff of air. If it blows the tissue off, you’re OK. If not, the hose is pinched behind the air-box.



If the hose is kinked or blocked how long does it take before you start leaking oil as you're riding. As the engine warms up the oil expands and build up pressure in the crankcase and if the hose is pinched it build up enough pressure to blow the seal out around the shift lever. You just have to put it back in. I have heard of some that have driven many miles without any damage except for a mess to clean up and a dangerous oil covered rear tire.

Donut, Doug,Coloma, Mi.
:patriot:

 
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#7 ·
Thanks for making it a sticky so quickly. My only concern is the title, perhaps something like:

Airbox Breather Tube (aka OIL LEAK!!!)
 
#11 ·
Thanks poolmaster for making it a Sticky.
If it saves one person from going threw that mess then I am happy. There has been so many that have had this problem over the years. One was quoted $300 to just put the seal back in on today's board and I am wondering if the dealer would have told him the real truth and they probably would not even know to fixed the pinched hose.

Everybody's friend
Donut/Doug :patriot:
 
#13 ·
I just installed a hypercharger and ran into this problem. The directions for the hypercharger said to cab off that breather hose with a supplied cap and clamp. I guess this was the wrong thing to do. My question now is, can I run the bike with that hose not capped as it does nothing for the hyperchager any way. And do you just tap the seal back in with a hammer? Will it leak at all or should I get it repaired at the dealer. Thanks in advance.
 
#14 ·
On my Hypercharger there is a black plastic fitting that the breather hose is connected to. The fitting is in the downward sloping metal bit that connects from the carb throat to the hypercharger base. And my instructions refer to plugging off the tube for the PAIR valve system, which I had removed anyway. There is also a carb vent hose that connects to another black plastic fitting in the base of the hypercharger.
 
#16 ·
I think I have found the problem.The hose that I capped off is a larger hose than the others. I think that was correct. The hose that you are talking about that goes to the throat of the carb does have a kink in it. I think that is where the problem lies. So now its just to get the seal back into place. Is it just a matter of tapping it back in witha hammer?

By the way Blackdot. I used to live in Halifax. Spent 24 years there in the Navy before I retired 2 years ago and moved back home to Newfoundland.
 
#17 ·
The larger hose is to the paired valve system which is fine. Although you should just remove the system so you don't collect water in it. Yes definitely make sure the hose has no kinks it it at all. Without it breathing properly it builds up pressure causing the seal to blow.

And yes just tap it back in. Make sure it even and everything but there usually is no need to replace or go to the dealer.
 
#19 ·
OK. The kink is out of the hose. The seal is back in around the shaft. Filter changed. New oil in the bike. No leaks. I have not taken it for a run yet. One question. When I drove it after installing the hypercharger, when stopped at a light, smoke was coming out of the pipes. I took this as a sign the bike may have been running a bit rich. I did re-jet and add a shim when installing the kypercharger but I did not touch the mixture screw as the directions did not say to do so. Could the smoke have been from the crankcase over pressureizing? Thanks in advance for the replies so far.
 
#24 ·
mine was

I did the pair mod, put it back together and room it for a quick spin. I heard a bit if a leak of some sort after the few minute ride and started looking. I took the oil cap off the engine and with the pressure built up due to the kinked hose it pretty much popped off. I heard the release of pressure so I peeked carbon side to see if I could the pinched hose but no luck. I went to the opposite side of the bike and with a lamp could clearly see the pinched hose. I stuck my fingers in there and pulled a bit and in kinked it.
Thanks for the heads up on this problem.
 
#27 ·
Can you post a picture of the hose you are talking about? Also a pic of the seal or it's location. Maybe the diagram from the service manual would help!
 
#28 ·
I don't have any pic. But the hose connects at the bottom back of the airbox and goes up over the front calendar. The seal is around the center shaft of the heal toe shifter. On a C bike it is the pivot point for the shifter - same place. I doesn't get damaged so you should be able to put it back in.
 
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