Reserve capacity

[Worty]

Just checking the fuel range of reserve on my '61 GF.  Ran out of petrol last week and had to get my dear wife to bring some out  .  I reckon 3 miles tops, and that was taking it easy.  I've got the reserve tap (no tube) on the o/s and used it today to try to use up the remainder of the fuel on a short run.  When it ran out, I took the taps off and recovered about a small plastic cup full of fuel.  It would be nice to have about 10 miles reserve at least.  All the japanese bikes I owned in the 80s seemed to be very generous.
I'm going to anticipate comments of 'don't run out' and 'top up sooner'  which is fine cos I'm not that daft.  Wondered if there was a way of increasing the range a bit or just being more careful now I now I've only go a thimbleful at my disposal.

[Lindsay S]

Hi Worty, the standard (3 1/2 gallon) tank on my ‘58 Flash has the lowest tap on the left so I use the right-hand tap as the ‘normal’ one. Both of the original Ewarts taps I have are identical.
When I ran out of fuel yesterday (26/1/‘25) I was about four miles from the nearest petrol station so I switched to the left-hand petrol tap and got there with ease at about 50 mph. When I filled it up, it took 11.3 litres, which is nearly 2 1/2 gallons, which would give about a gallon reserve. And yes, I had definitely run out on the right tap, tickling produced nothing on my finger!
I have been trying to find out what the ‘official’ reserve capacity is (which is why I landed on this post) but all to no avail (I haven’t asked Alexa yet!). there is no indication of what it should be in the ‘64 reprint of the owners manual that I have. So, until I do another ‘test’ like the unscheduled one yesterday, it looks like I have a reserve of one gallon on my bike.
Incidentally, when the fuel gauge on my R E  interceptor 650 starts flashing, that still has  about 4 litres remaining.

[limeyrob]

I've worked on the assumption of around 1/2 gallon at absolute best and more likely a few pints  There's the stand pipe height on the main tap - if it has a stand pipe.  The parts book lists both taps as the same part number which means the reserve is what ever stays one side of the tank. Its easy to open both taps for a fast run then forget to go back to one, I've done it!
If you don't have a stand pipe and have one tap as main and one as reserve then in my experience you can only count on a few pints if the road is bumpy.  A GF ridden gently could reach 80 mpg which would give 20 miles on the last 2 pints of fuel.

[berger]

you two tap people are lucky , i ran out on betsy a few miles out of yarnmouth and had to lean her over near onto the floor and blow into the honda tank , i just managed to tease her to a garage following my sat nav mate [ rip ] for about 8 miles with my bum tightening up and just got there as she conked out

[Lindsay S]

I wonder if the new Indian-made tanks don’t have the internal stand pipe that the original Birmingham-made tanks might have. Looking at my tank, the right-hand tap is slightly higher than the left but I can also see, from the outside of the right underside, what appears to be part of a tube going up into the tank. I can’t see much, looking in through the filler cap hole but when I get my new tank (on its way from India I hope!) I will stick my bore scope into my empty original tank and see what’s going on.

[Rex]

In my experience it's the taps which have the "standpipes" rather than the tanks, unless I'm misunderstanding what you mean?

[Lindsay S]

Well I am writing this with a bit of a red face! The bike cut out whilst on the right-hand tap again today and this time I knew I was not short of fuel. I again switched to the left side and all was OK. When we got home, I checked the right-hand tap and the flow was OK but when I looked at the carb filter, I found it choked with black debris adjacent to the inlet on the banjo that corresponded to the right-hand tap! I had thoroughly cleaned and rinsed out the tank before fitting it but I will have to keep an eye on that filter from now on. It beats why the filters on the taps don’t stop this stuff as their mesh looks a lot finer than that of the carb banjo filter.