petcocks/reserve

[Sava66]

Hello all, Seeing how my odometer is INOP right now, my goal is to not run out of gas. I know it sounds simple, but people do it all the time!
One of the ways I think would be helpful would be to figure out if one of the petcocks could be used as a reserve. i asked the guy who owned the bike before me and he didn't have a clue. His way of turning on the fuel was to "just turn them both up". i tried just turning the left side to 12 and keeping the right side at 3 o'clock but then for some reason (joking) it just runs on one cylinder!
I know my bike is heavily modded but can anyone begin to tell me how I can figure out if there is a reserve petcock, one that I can flip on when the bike is getting low?

[Bob_Roller]

First, you have to make sure that there are two different length tubes on the the fuel tap inside the tank, some owners, have removed them, leaving you no notice that you are low on fuel, until the engine sputters and quits  .

The fuel taps on the airhead bikes, are quite simple, if the handle is at the 6 o'clock position, you are in 'Normal', fuel will stop flowing when you get to around .6-.8 US gallons in the tank .

Then you turn the handle to the 12 o'clock position, this 'Reserve', you've got about 20ish miles left of fuel .

With the handle in either the 3 or 9 o'clock position, fuel is turned off .

This is the position you should use, when the bike parked for the day .

Wouldn't be a bad idea, to remove the fuel line from the fuel tap and make sure the fuel is really shut off .

When I got my '82 LS two years ago, even with the fuel tap in the 'Off' position, the fuel wasn't shut off, the rubber washer inside the fuel tap had grooves in it, allowing fuel to continue to flow, even in the 'Off" position .

[Sava66]

excellent idea, Bob. Especially because the other day i was putting the fuel on and some leaked out, so it might be time for new tubes. So with the Norton, I rode normally with the left one off and the right one on, whenever I heard it spit and sputter, I turned the left one on. But you're saying, with the BMW,  I should keep them both "on" at 6, and then when it spits and sputters, turn them both to reserve "12"? I've been keeping them both on reserve. It is a different fuel tank so there might not be a reserve function as you said. i just stick a flashlight inside to check?

[Bob_Roller]

From the sound of your description, you have a fuel tap on each side .

The North American version twin shock bikes, only had one fuel tap, on the left side .

I don't know if you can see the intake tubes from the fuel filler cap area .

Only way for sure, is to remove the fuel taps from the tank .

BMW used two different fuel taps, one the Germa has the fuel line coming out at the 6 o'clock position, the other, Karcoma has the fuel line coming out at the 3 o'clock position .

The Germa tap has a small plastic fine mesh filter under the nut that secures the barbed fitting that the fuel line goes onto .

The Karcoma tap, should have a fine mesh metal screen inside the tank, covering the fuel intake tubes .

[Sava66]

removing the fuel taps (petcocks) requires draining the gas, right?

[Bob_Roller]

Yes it does .

Even when no fuel comes out of the fuel tap, there is still fuel around the area, so have a drain pan ready to contain the fuel when it drains out .

[Barry]

As Bob said you can't use all the fuel in the tank because the reserve straw is a little above the bottom not to mention there's another litre or so of  fuel on the other side of the hump. If you drain off as much as possible through the petcock and then tip the tank on it's side before removing the petcock you should be OK.

[montmil]

... I think would be helpful would be to figure out if one of the petcocks could be used as a reserve. i asked the guy who owned the bike before me and he didn't have a clue. His way of turning on the fuel was to "just turn them both up" ...

Do you have dual petcocks -left and right sides- on your R65 tank?

[Rob Valdez 79 R65]

Also, in many climates, you should drain your tank once an year and remove the petcock(s) to allow you to drain any water that might be in there.

It can get in by two ways, that I know of - rain leaking in, and condensation.

And I am pretty sure that water is heavier than gasoline.  The problem with that is, it stays at the bottom of the tank, slowly eating away at the metal.

If you have two petcocks on a twin-shock bike, yours either:
1) has a tank from a different model
or
2) has had a second petcock added to the original tank (not unheard of).

[Rob Valdez 79 R65]

Oh yeah, definitely a non-R65 tank!  

No wonder your "friend" thought you had a larger bike!  LOL!