Roadster tank capacity

I asked a similar question a few years ago but I can't find the thread now.

I bought a new steel roadster tank to replace my fibreglass one and when I was leak teasting and flushing it with it in my hands I noticed how much fuel was still left in one side even after some acrobatic draining from the other.  The new ones not only have a high saddle but there are some baffles welded inside too which exacerbates the situation.  Therefore, when running dry on the normal side, switching to reserve side gives access to the trapped fuel in that side but still leaves an amount stuck in the standard side which can't flow round.

I resolved this in two ways. Firstly I set the fuel lines up as you suggested, with a cross over pipe between both sides and secondly by cutting the standard fuel tap down to the same height as the reserve.  Like this you have options. Run on one side habiutually and when that runs out use the trapped fuel in the other side as the reserve. Open up both fuel taps occasionally to equalise the fuel in both sides and peer in so you know what you've actually got in there, or use both taps and keep a good eye on the level.... but you dont have a reserve.  The down side is that after some spirited riding when on one tap its possibpe to slosh some from your closed tap side around and then when you run out you don't have anywhere near as much in the trapped fuel side as you hoped!  I've never got stuck yet using one tap with the trapped fuel as reserve.

I seem to only be able to use 10 litres of fuel between not over full and not running dry. Not much at all and certaily less than my fiberglass tank. 

I had the idea that as both Roadster variants had similar external dimensions, the thicker-walled glass-fibre tanks must have a lower capacity ?

Even at motorway speeds, I reckon on 100 miles to reserve on my steel-tank 850.

I fit the reserve tap on the right, which is not convenient for operating at the same time as trying to keep the throttle open but the alternative is that a visual check of fuel level via the right-hand-side cap suggests that there is more fuel than is actually accessible. The reserve stand pipes can be quite high.

We always used to go to rallies with a pewter tankard. I can confirm that these are quite handy for removing fuel and transferring it to the other side, but also that old fashioned pewter does rather hold on to the fuel taste.

Norton singles simply use one side as reserve with no standpipe which is what Graham P. suggests. It works well, but I suspect that the tunnel is higher and very little fuel passes over.

To access all the available fuel without having to stop and try sloshing it over the hump I use two reserve taps. After an experiment, where I strapped a can of fuel to the saddle, I know I can get about 8 miles to completely empty from going onto reserve on one tap.

Roadster Tank.

Capacity of the Roadster petrol tank can be increased by filling it up with the machine on the side stand; if your Ceandess cap rubber is in good condition then it won’t leak when returned to the vertical plane for riding.  I can achieve 140 miles before going onto reserve; single 32mm Amal concentric carburettor with a very gentle right hand. As ever, your tank’s capacity, and ironically in this case, mileage, may vary. 

I use two reserve taps on my steel tank 850 roadster. This is because when I used the standard arrangement I once ran out of fuel, looked in the tank and saw plenty of fuel but was unable to slosh it over to the reserve side despite leaning the bike over as far as I dared.

I made the same experiment, in my case I got only about 5 km, maybe because the road was bumpy and curvy and also some altitude-changes about 50 metres were involved.

I think there will be only sufficient reserve on a straight road without acceleration.

Regards Marcel

Edit: The slope was about 10% with the altitude-changes during less than 1 km distance.