Fuel Tank Petcocks

[decorn33]

My '84 has the standard left side petcock with the fuel line splitter that sends a branch through the air cleaner assembly to the right carb.  Has anyone successfully had their tank modified to add a petcock to the right side? Is the tank even set up inside to do that?

[MR.E]

I chopped a tank recently, i'll dig out the pics that may help you answer the question

Elliott

[Barry]

There is no outlet on the RH side. I recall reading that someone brazed a 2nd boss into the right side of the tank but it's hardly a minor task unless the tank is due for complete refurbishment inside and out.

[Rob Valdez 79 R65]

In over 30 years of ownership I never felt the need for a 2nd petcock.
If you DO happen to run out of fuel while on reserve, you can always remove the tank (< 5 minutes) and tilt it to the left to get all of that fuel to the petcock side.

But I don't mean to intrude on your fun.

[decorn33]

I was in a discussion with a buddy who has a /2 and he pointed out that the R65 tank has two low points in the design that his does not have.  On the left side it serves the petcock. On the right its just a low point. The suggestion was made that if moisture condensation were allowed to remain, it would be an obvious spot to rust if the lining were compromised, so it got me thinking about it.  I guess in these days of Ethanol gas though, water separation isn't as much of a problem as it used to be.

[Rob Valdez 79 R65]

In Indiana we have a pretty dependable lay-up in the winter.  I always chose to drain my tank at this time and remove the petcock which allowed me to clean everything out once a year.
Then I would let the tank air out for a few days before putting everything back together for the remainder of the winter.
As a result, I have a tank for sale that still has the original liner in VG condition.

[montmil]

Even if one does not live north of the Mason-Dixon, it's a good idea to drain and dry the fuel tank once a year. With the tank removed annually, an inspection can be made of all under-tank items that may need a little love.

This minor chore can be a tank saver -and there's no guarantee that twin petcocks will prevent water collecting in the lower seams of any Airhead.

An interior relining and repaint of the modified fuel tank is a foregone conclusion. That said, it's the bike owner's decision to mod, chop, cafe, customize... whatever.

[Barry]

A 2nd petcock would not allow a small amount of water to be removed or at least it would leave a much bigger volume behind than I ever found in a tank.

Anyone who has drained a tank will know that you cannot completely empty the contents via the petcock because even the reserve straw stands a little above the low point. This is a deliberate design to prevent sediment getting into the carbs. You have to remove the petcock to get the last 1/2 litre out and you really have to remove the tank or tip it well over to do that sensibly and safely.

There's no substitute for removing the tank and drying it out properly although having said that I'm not finding any detectable amount of water in these days. That's the trouble with ethanol. Water is absorbed up to the saturation point then the whole lot separates out so you are likely to find either no water or a lot of water.

[Matt Chapter]

My '86 tank has two petcocks, I'm not sure if the '85 - '87 tanks are a direct swap or not...

I don't particularly care for the second petcock on the RHS.. I dislike removing the throttle hand from the bars to turn it on / off / reserve, and with the occasional carb float stick, I'm much more likely to forget to turn it off when parking...

[Rob Valdez 79 R65]

I'm not sure if the '85 - '87 tanks are a direct swap or not...

They are not.

[DgM]

I added a right side petcock to a gas tank for my 1983 R65.  The tank had been stripped, I had a talented welder cut the bung from a bashed donor tank, cut and weld into stripped tank.  Smoothed welds, primed, painted, striped tank.  Connected gas line on right side to 't' fitting (as on left side), connected transverse hose to balance draining, ran short (as on left side) hose down to right side carb. Looks factory, not that big a deal but you need a donor tank with a good bung.  I know...bung.

[bruce_launceston]

If your thinking is that having a second bung will minimise the moisture sitting in the bottom of the tank then the design of the fuel tap negates this benefit.
There is a second short straw on the tap that prevents the draining dry via the tap.

I guess this is there so you don't pick up the shit that sits in the bottom of a neglected tank and suck it into the carbs.

Simpler to take the tank off every year or so and remove the fuel tap, drain the tank, air dry it then start again with clean fuel.


edit (Sorry Barry, I missed you post saying much the same).

[DgM]

The right side petcock allows ALL the fuel in the gas tank to flow into the carbs, save for the tiny amount swilling about under the petcock inlets.  The right side petcock releases the generous amount of fuel normally hanging around unused in the right volume of the tank, a sort of reserve to the reserve.  Regardless of single or dual petcocks gas tanks should be flushed/drained once a year to get rid of typical junk from the pump.

[georgesgiralt]

Hello !
On my bike manual, it is written to lean the bike on the left cylinder to get the remaining fuel available when running dry....
I've done this once, at 3 am coming back from Ireland on a French motorway. It was not enough to reach the petrol station. My wife still moans about it... 25 years after....

[Bob_Roller]

You need to get the front wheel elevated, like on a curb, or whatever you can find, the higher the better .

Then tilt the bike to the left .

I did some testing on this about 6 years ago .

I believe the additional volume of fuel was a bit under .5 gallon US, or around 2 liters, that I got out of the fuel tap in reserve after running the tank 'dry' in the reserve position .