Air Box Connection

When I bought my 2007 it had a red hose all the way from the small tank up near the headstock running to the back of the CARC.
Looking under the tank I see the spigot is labeled Airbox.
The airbox has a hose at the top all folded up but it's about 6" too short to reach the spigot the front, was there something else in between.

I'm thinking I should just run the red hose straight from the tank up front to the airbox

What do you think?

The hose folded up at the airbox is probably the gearbox breather, all the CARC bikes had one.

I'm guessing the red hose is an extra provided by the previous owner. Personally, I'd leave it where it is.

So the gearbox breathes into the airbox then

No, the gearbox breather hose just goes up under the tank and is usually tied to some point on the airbox.  It is not connected to the airbox internals.

Here is the hose of which I speak, definitely attached to the Airbox but too short to reach where the red one is.
The red hose used to go all the way to the back of the CARC but I shortened it and dropped out the bottom of the engine,
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The black one was just coiled up.

That's the gearbox breather, it simply vents to atmosphere. From memory it just pokes up somewhere under the seat/around the airbox.

The thing is, unlike the engine where there is always positive pressure due to leak down past the rings and a constant change of volume of the crankcase as the pistons whizz up and down the gearbox has a constant volume and the only real *Change* to its pressure occurs as it heats up and cools down and the 'Air' and 'Oil' inside it expand and contract. That change is pretty minor so all that you need to do is vent it so that it doesn't pressurise the seals.

Nothing should ever come out of it oil wise. If it does it's an indicator that something horrid is happening in the box which is unlikely with any of the 'Nuovo Six Speeds' as they are pretty much bulletproof!

Pete

PS. Unless it's the curly hose that goes to the middle of the throttle bodies. If that is the case it's the stepper motor hose and needs to be plugged onto the spigot on the airbox. Bit hard to see in that pic. Sorry.

Kiwi_Roy wrote:

.... The red hose used to go all the way to the back of the CARC ....

What? Where?

First of all, looks to me that the gearbox vent is probably the hose seen at the bottom-right of the photo, the one that goes over the pump plug...

The 1100s "Blow-by system", as it is called at the part catalogue, should be this:

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- Running a vent from the "housing" (as it is called at the part catalogue) at the end of the CARC (or anywere) is uselles as at the 1100 is is vented through the pipe "8". FYI, this vent, makes a hudge diference in the operation of the "blow-by" between the 1100 and the 1200...
- Running a drain is also uselles, as whatever oil in the "housing" is aupposed to be drained from it, returning to the engine through the pipe "10"
- The "housing" is supposed to be conected to the airbox, at the airbox "port" shown at the image, so oil fumes (if any) eventualy get burned.
- The pipe that is too short to connect the "housing" and airbox, is maybe one of the other pipes marked "14"? Or someone has cut it short?
- I'm not very surre that the red pipe is connected to the correct port of the "housing". The image is not very exact regarding the "housing" ports

Looks like someone messed something, trying to fix something - or nothing.
My guess is wanted to avoid the "too much oil in the airbox" issue, that should not appear at a 1100, as it has 2 major differences to the 1200 - the "housing" is vented, and the oil flow to the cooler is thermostaticaly controlled. If there is excessive oil in the airbox of a 1100, there is some problem...

Lastly, the airbox should have no openings to the enviroment after (downstream) the airfilter, either open ports or ports conected to pipes that are open, as it will draw whatever can fit through this opening. An open (lost plug) airbox drain pipe, down near the weel, may bring to the engine more dust that if there was no arfilter at all.

Thanks Pete, I agree with Petros the gearbox breather will be that smaller hose to the right.

In the diagram Petros posted it clearly shows the "the housing" (1) coupled to the airbox with the long hose (14),  to the tit above the left intake rubber. The marking on "the housing" supports this, it has "Airbox" in raised letters beside where the red hose is at present.

In hindsite the mystery black hose was connected to the 3rd connection of the idle speed stepper valve. I have it off at the moment trying to fix it but it was connected where the hose (14) is shown in Petros's diagram, clearly wrong.

Perhaps the PO thought there was too much oil in the airbox so vented "the housing" (1) to the rear of the CARC with the ugly red hose. I seem to recall you caution against over-filling the engine oil.