Another place for dirty air to get sucked into airbox on '06 S3

[BulldogHooligan]

I have taken my airbox off several times and have always put the hoses back on upon reassembly. Recently, I blocked off the SAI and discovered a small nipple below the large port where the former SAI hose attached. After posting on this forum and receiving many replies, I decided to block off that little nipple because it allowed dirty air to get sucked into the clean side of the air filter. Well, guess what ? There is another nipple with a hose attached to the left rear of the airbox that is apparently just a drain tube. This nipple ports to the clean side of the airbox also and it just snakes down to below the bike.

Can I block this off ? Or, would it be unwise ? Is an airbox drain tube really needed ? At the very least, it should have some kind of filter attached to it.

[S3FTW]

I wouldn't block it off. If you do get going quick enough and great enough RPM's during the rain then you may start pulling in mist or small amounts of water, once collected along with temperature cycling and causing condensation if you have no where for that liquid to go it may end up in your engine.

Just my thoughts on it and I'm no professional but it seems a good idea to leave a drain tube. Maybe get a one way check valve so that it will not suck in air but will still let out any fluids?

[DavePreston]

I have ridden my 2006 ST in all sorts of Seattle weather for 14,000 miles, with no mods to the airbox other than a K&N filter. I would think there was a reason for the drain tube to be put there, and I don't see what you would gain being worth the possible problems caused by something the factory guys know and you do not. Since putting it there makes the bike more expensive to manufacture, I would doubt it was put in on a whim.

[Stampy]

Originally Posted by DavePreston

I have ridden my 2006 ST in all sorts of Seattle weather for 14,000 miles, with no mods to the airbox other than a K&N filter. I would think there was a reason for the drain tube to be put there, and I don't see what you would gain being worth the possible problems caused by something the factory guys know and you do not. Since putting it there makes the bike more expensive to manufacture, I would doubt it was put in on a whim.

+11111!!!!!!!!

[Martin_R]

Drain is probably there to prevent hydro lock and major engine damage on a spill.

Big problem on early Triples, where on a drop oil would flow through crankcase breather into airbox and into engine -> Cylinder(s) fill with oil -> Unsuspecting owner picks bike up and tries to start -> Engine hydrolocks as oil will not compress -> Connecting rods and/or crank bends -> Totaled engine.

So no, the drain cannot be blocked and I suspect a filter would prevent oil exiting too. I agree that it is bit of a stupid design. On intuition a better place to put the oil would be to lead it back to the crankcase. But then it should be some one-way passage so it does not end up leading even more oil into airbox.

[nodrog]

mine has a plug in the end of the hose, it came from the factory like that. its just a drain hose for any oil that may build up in the air box, its not designed to suck in air so it does not matter if its blocked or not. most other bikes i have owned have had a similar setup.