GAS TANK VENT

[DgM]

Removed gas tank from my 1983 R65, observed vertical metal tube open end down coming from tank.  Is this the breather/ vent?  I was under impression venting was through gas cap.  Any procedure to clean tube?  Tank has some crud and while cleaning would like to address everything at same time.  Any help would be appreciated.  Thanks.

[MrRiden]

DgM,
That tube is an over flow drain. Look inside the filler opening and you should see a small hole right at the neck, that's the other end. It is meant to catch and drain excess fuel from expansion or an over filled tank. There should be a hose connected to the bottom tube to direct any dripping away from the hot engine. you should be able to push an insulated piece of wire through or just blow it out with compressed air.
rich

[montmil]

I also found the overflow drain tubing missing from the tank overflow vents on both my '81 and '83 R65s.

Believe someone in our group actually had a brief fire while fueling his bike due to this issue. Anyway...

I visited the local Ace Hardware & BMW Supply store and secured a couple nylon 90-degree "L" fittings that would accept some vinyl tubing matching the O.D. of the drain pipe. One really short and one lengthy piece of tubing, a few black zip ties routed the drain line to a convenient sized hole on the left side passenger foot peg bracket and I'm now a bit safer. Any fuel overflow dumps on the ground beside the rear tire.

[DgM]

Thanks for info.   Will install hose and away from top of engine.  Does overflow act as vent also?

[Yikes]

You're right the first time.  All the venting is through the cap.  If you are not experiencing stalling (remedied by loosening the cap) or hear bubbling in your tank when you open the fuel stopcock after being shut for a while,  your cap is venting OK.  

[tagordon]

First let me say, do not ask me how I know.
Do not allow gas to get on your tires.
Gas will cause your tires to check and possibly fail.
OK, I had the misfortune to have a very small leak that did not leave any stain evidence.
It sprayed gas on my rear tire which checked.
Manufactor replaced under warranty as no evidence of any cause other than defect.
Second tire not replaced under warranty.
Currently on third rear tire this year and very careful tofrequently inspect bike for any fluid leaks.

[Rob Valdez 79 R65]

What is 'checked' in 'Merican English?

I have never heard of gasoline having such an extreme effect on a tire.

[donbmw]

I have seen jet fuel deform tires. A tire would have to stand in a large amount before you would see a effect from gas. I think a oil or brake fluid would do more harm than gas.

Don