Oil Drip (from bottom black tube)

[Townie_imp]

Hi Folks,

My first post here (though I've been lurking for a month or so), and thought I'd ask the collective about something I'd saw today.

2014 CB1100 (Canada model), about 300Km on it so far (1 month).

After a 2 hour ride today I parked the bike. An hour later I saw a bit of oil underneath the bike, about 2" diameter spot. Looking closer, it's a very slow drip from a black tube near the side stand (the black tube is next to the pink, plugged tube).

Is this something I should be worried about? Oil level in the window looks fine, ie. I don't think its overfilled. This is the first time I've seen this, and I would have noticed it if it happened before.

Thanks!

[Lord Popgun]

Are you sure its oil? The little black hose is the Fuel Tank Breather hose. The plugged hose is the Crankcase Breather Drain Hose.

Did you over fill the tank by any chance?

[Townie_imp]

I thought it was oil, since it looked like oil and was of similar color to new oil (remember, only 300Km on the bike). It also left an oil-like stain on the interlock brick many hours later. If it was fuel I think it would have totally evaporated off the brick in the heat of the sun.

But now when I check the black tube, there are no traces of anything. If it was oil, I would think there would be small amounts at the end of the tube.

So, let's assume it was actually fuel that dripped out. I think this tube is for fuel tank overflow. But the tank was only 2/3 full. It was a reasonably warm day (25degC), but that shouldn't cause any big amount of fuel expansion.

It also looks like I had some drip out overnight last night in the garage. Cold engine. The only thing I did prior to this was clean the headers (Optiglanz works great), with a thorough rinse with the hose. This must be a red herring, though the timing is an awful coincidence. Never had any fuel/oil dripping prior to the cleaning & rinsing.

[TonUp_imp]

2014 CB1100ex
My bike did the same after a long run. Looked like orange gunge - a mixture of oil and grease. It dropped out of the black hose pipe near the sidestand. It does not do it all the time. Checked the oil level, all ok.

It could be some sort of packing grease applied during assembly?

[SMI Tool_imp]

I lube my chain too much and get a small drip from down there.

[Lord Popgun]

2014 CB1100ex
My bike did the same after a long run. Looked like orange gunge - a mixture of oil and grease. It dropped out of the black hose pipe near the sidestand. It does not do it all the time. Checked the oil level, all ok.

It could be some sort of packing grease applied during assembly?

Its weird that it would be anything but gas. The service manual says it is the tank breather, but I have not followed it to see if they have it mislabeled.

[Lord Popgun]

OK, I traced the pluged line hanging down and it goes to the back of the air box. I think there are/is some miss-labeling in the service manual. Edit to add: or I guess not. The common service manual says: A crankcase breather separater is necessary within the system to prevent moisture from contaminating the engine. Moisture vapor is not allowed to pass through the air cleaner and into the engine. Moisture is collected in a sealed crankcase breather tube.

Then it says you pull the plug and drain it.

Haven't followed the black one yet (labeled as tank breather)

[Townie_imp]

I was only able to trace the black tube to the air intake area, and then I lose sight of where it goes.

When the drip happened in the driveway, I mopped it up with some paper towel. It seemed to have an oil-like consistency, and that amber color of new oil, but I didn't give it the sniff test to see if there might be any fuel in it. I'll do that if it happens again.

I suspect you're right that the black tube is the fuel tank breather. But it's weird how this drip happened, or what the liquid actually was.

[Lord Popgun]

I looked at the black hose on the bike using an inspection mirror and more in depth in the manual.

The fuel tank breather hose comes from the fuel tank and goes to the EVAP canister. From there it comes out another fitting on the canister and hangs down by the plugged hose.

On one drawing the black hose that hangs down is called the fuel tank breather hose, and on another it is called the Evap Canister Drain hose.

Just for info, there is another hose on the canister--Evap canister to solenoid valve hose.

I can imagine that any fluid that sits in a can before draining out may be, well, nasty.

If you would like to see the drawings, PM me your email address. We cannot post copyright material on this site.

[Pterodactyl_imp]

You could try plugging the line with some absorbent paper towelling (kitchen paper) and the removing it after running to get a better idea of the amount of, and the type of, fluid you are reporting.

Cheers