Petrol tank breather lines

[injun]

After having taken off my tank( 2003 R1150R) for the first time, and having reassembled the bike, I only now realise that there is a need to be careful to mark which tank breather lines are connected to which, as - supposedly - failure to reconnect properly will give me big problems when I try to run my bike?

I dont think this issue is mentioned in the BMW repair and overhaul manual, but i see that some of you fellow listers have mentioned this when discussing the tank on/off drill.

So my questions are:

Does it REALLY matter if the breather lines are switched at the connections?

-And if so - how can I find out which breather line mates with which?

[digga]

When i took my tank off it was obvious which line went to which.
This was due to the fact that i had Quick Disconnects( QD's) fitted.
With the QD's they have Male/Female fittings which are reversed on the other line

It sounds as though your lines have the Qd's removed

[Ves]

When i took my tank off it was obvious which line went to which.
This was due to the fact that i had Quick Disconnects( QD's) fitted.
With the QD's they have Male/Female fittings which are reversed on the other line

It sounds as though your lines have the Qd's removed

Seems you're talking about the gas lines... he's talking about the breather hoses.

Yes, it makes a difference which you hook them up. In the future you can just make sure that one of the connectors stay on a hose that connects to the gas tank, and the other connector stays on a hose that goes to the canister or vent line. That way you can't assemble them incorrectly.

[boxermania]

Ves +1

There are many ways to identify, taping, leaving one plastic connector fiting on the ones coming from the tank and the other on the ones going away from the tank, but the easiest way for me is to use a paint pen and place dots on oither side of one of the hoses......that way I know those with the dots go together and so the unmarked ones.

[injun]

OK folks, but I flawed and did not mark them. So how do I now know which is which - and what are the conesequences of driving with them swapped?

[digga]

You are quite right Ves..... speed reading again

I think i only have one breather ( we don't have that canister thing),,, i'll check to night.IIRC thats the small diam' hose that connects to a plastic ridged connector just behind that panel/trim on the RHS??

[csalt]

Injun,
Should not be a problem for you as long as the breather lines do not go to the bottom nipple on the throttle bodies. My bike is a U.S. model and in the case of reversed hoses with the canister in place the vacuum created by the throttle bodies was sometimes connected to the drain line (by the right foot peg) and pulled in moisture from the drain line. Trace your lines down and they should be just overflow drains.

[Boxer]

I'm often confused about any number of things so I must confess, with as many times as I've had that tank off I can't remember which is which. Once I had to use the old blowing from the end trick with the gas cap open to tell which one was the overflow and which...whatever the other one is. There is a surefire way to tell by blowing backwards on the tubes. If air can be heard coming up out of the tank, then its the line to the cannister. If you can't hear air, and it feels like blowing up nothing, then its the other one.

Disclaimer: I may be totally confused again and have it bassackwards, but this is the way to tell if you can remember which way is which. Someone please chime in here and tell this guy the right way!

[Ves]

... Trace your lines down and they should be just overflow drains.

I think the point your making is that one of the lines coming from the gas tank is an overflow line and that is connected to the hose, on the motorcycle, that does not hook up to the canister... it just drains to the ground. The other hose from the tank hooks up to the canister.

How do you know which is the overflow hose on the gas tank?... Open up you gas cap. See the little hole on the rim? It's about 1/8" diameter. Blow into one of the breather hoses hooked to the tank. When you blow into one of them, air will come out this little hole. That's your gas overflow line. Hook that up so it drains to the ground and hook the other hose to the canister.

Right?

Disclaimer: blow... don't suck on the hose...

[boxermania]

injun

If the hoses were reconected wrong....as you didn't make that fact very clear in the wording of your first post, all you have to do is disconect the two hoses coming from the tank, after marking and switch them, there are only two possibilities.......and your first one try was wrong.......

[Buckster]

I did the same thing. It would be nice if they forwarned you in the manual.
Follow Ves's instructions to make sure you have them hooked up right and in the future leave one connecter in the bottom hose and one in the top hose that way there will be no mix up when reconnecting.

[injun]

Hello again folks,

Checked my bike again today. Seems like both breather lines end up behind the RH footrest, so switching them in the under-tank connectors should be of no importance. Is the charcoal canister thing something for the US market only? Sometimes US environmental regulations are stricter than the European ones.

(Still my EURO-spec BMW is much more environmental friendly than my old Indians, as there is no automatic rear tire lubrication, no spray lubing of the bikes and faces of fellas riding behind me, and no oil soaked asphalt wherever I park. Actually my Beemer has not leaked a single drop of any liquid on my garage floor in two years. With an indian that would have made me deeply concerned)

)