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What's this hose for?

Posted: Mon Jun 11, 2018 8:50 pm
by slowdown

Over the weekend I decided to do an SAS removal, charcoal can removal and fit a new airbox.

I'm all done now, just waiting for the new filter oil to dry, and then will re-install everything. However, I found a mystery hose, and its making me have a lot of questions about what it is and whether I screwed something up, or somehow disconnected part of my cooling system. This hose isn't referenced in any part of the SAS removal instructions, so I don't think its related to that system.

The mystery hose has been on the bike for as long as I can remember. It was attached to a little holder on the Left side of the radiator. The terminal end that was visible when the bike is put together has a clamp and a screw plugging it up. The other end was somewhere inside the bike, as I discovered when doing the SAS removal.

When I was removing the SAS, I was working in the front left of the bike. There I found the other end of this mystery hose, and I believe it was connected to nothing. I pulled it out of its holder on the Left hand side of the radiator, and traced it to its end. I don't think it was attached to anything at all. Its possible that it was, and I inadvertently disconnected it. As it wasn't attached to anything as far as I could tell, I removed it.

Incidentally, while doing the install of the airbox I had my coolant compensating tank exposed, and I noticed that it is very low. The bike has been running around 180 degrees F. There has been no coolant leaking on my garage floor or anywhere else that I've ever noticed.

There are 2 hoses that take off out of the coolant compensating tank. The one at the bottom of the tank seems to run over to the right hand side of the bike and connects to the cap on the radiator. The second hose that takes off from the top of the compensating tank runs forward on the bike, and then down in front of the front cylinder (behind the radiator), and just terminates 5 or 6 inches from the ground. It isn't plugged up, it isn't connected to anything. I assume this is a drain line for the compensating tank in case it is overflowing, but since I'm a very amateur mechanic assuming anything is not desirable. Is this supposed to be plugged up, or connected to anything? Do either of these hoses have anything to do with my mystery hose with the bolt in it?

I looked at a few parts fiches. They show the 2 hoses coming out of the compensating tank, but it doesn't show where they connect to, and I can find anything that references the mystery hose.

Re: What's this hose for?

Posted: Mon Jun 11, 2018 10:24 pm
by slowdown
I'm silly. I found my answer after reading through several threads here, revisiting the old airbox, and reviewing the Rottweiler supplied directions again.

The mystery hose is simply a drain line for the stock airbox, which is now sitting in the trash can per Rottweiler directions. The part shows up on the parts fiche when one looks under the air/filters section rather than the cooling system section. The parts fiche even shows the bolt in it. I do wonder though -- how is it supposed to drain anything from the airbox when there its plugged with a bolt? I remember now, when I pulled this hose off the bike it was partially full of gasoline-smelling fluid. I'm kind of confused how its supposed to be drain hose when one end of it is plugged off however. :?:

Maybe someone with same question in the future will see this thread.

Carry on!