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Roadster Reserve

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Roadster Reserve

Posted by gary_painter at October 30. 2018

My Roadster petrol tank will be in need of new taps when the time comes to put some juice in it.

I was studying it the other day and wondered if the main feed had a stand pipe, as the reserve tap is specified by a label.

Yes it does have a stand pipe and the reserve does not, as per standard practice.

However I also observed that the tunnel seems to be higher than the stand pipe, so the reserve side will only ever hold what is below the tunnel regardless of the level that the stand pipe drains the main side to.

So I have a question for you buffs... If I run two "reserve" taps. In other words two without stand pipes, then will I get a sufficient reserve capacity from the fuel stranded in the opposite side of the tank to that which I first use?

It just seems to me that once the level falls to the top of the pipe on the main feed, then the fuel below it, in that side of the tank, is left behind and not useable? How can it make it's way to the reserve tap? Without the antic of stopping and leaning the bike over, to tip the fuel over the weir of the tunnel. (Or is that the second reserve..? Undecided)

If I'm right I should extend the range of the main tap and still have the same in reserve. by using two non-stand pipe taps.... What do you reckon?

Re: Roadster Reserve

Posted by john_holmes at October 30. 2018

I bought a TR6 fitted with 2 reserves, ran out of petrol and turned the second tap on, got 200 yds and ran out. The vibration and movement reduced the amount trapped by the frame rail to virtually nil. Fitted a main tap promptly.

Re: Roadster Reserve

Posted by mark_savage at October 30. 2018

Previously gary_painter wrote:

My Roadster petrol tank will be in need of new taps when the time comes to put some juice in it.

I was studying it the other day and wondered if the main feed had a stand pipe, as the reserve tap is specified by a label.

Yes it does have a stand pipe and the reserve does not, as per standard practice.

However I also observed that the tunnel seems to be higher than the stand pipe, so the reserve side will only ever hold what is below the tunnel regardless of the level that the stand pipe drains the main side to.

So I have a question for you buffs... If I run two "reserve" taps. In other words two without stand pipes, then will I get a sufficient reserve capacity from the fuel stranded in the opposite side of the tank to that which I first use?

It just seems to me that once the level falls to the top of the pipe on the main feed, then the fuel below it, in that side of the tank, is left behind and not useable? How can it make it's way to the reserve tap? Without the antic of stopping and leaning the bike over, to tip the fuel over the weir of the tunnel. (Or is that the second reserve..? Undecided)

If I'm right I should extend the range of the main tap and still have the same in reserve. by using two non-stand pipe taps.... What do you reckon?

I've fitted two reserve taps to get the full capacity of the tank, it's a Roadster so it's needed. There's plenty of fuel left on the other side of the tank as you have already observed once one side is drained. I have to be careful sometimes as I run with both taps open. I haven't run out....yet.

Re: Roadster Reserve

Posted by gary_painter at October 30. 2018

I think we'll ALL run out of petrol in 200yrs John. I think you did well really..

The tunnel must be configured differently on your TR6 for the fuel to level out to that extent. Thinking about it most bikes have a more acutely angled top tube than a Commando, which extends much further back than normal and lies flatter. That makes most tunnels low enough at the rear to need a stand-pipe to form a reserve. The tunnel on the Roadster does seem a lot deeper than I've seen on other bikes and doesn't drop away much at the rear either, hence my thinking with a "natural" reserve.

However you did get me thinking how the fuel sloshes around in there, and I concluded that most of the surge is going to be back and forth from braking and accelerating. So the fuel can quite easily level the sides when it's all up the back end, but hopefully to a lesser extent on the Roadster with it's high tunnel.

 

Mark, thanks for confirming my thoughts. You obviously though along the same lines as me and tried it out. Pleased to hear that it works. How far do you get on reserve in this configuration?

Re: Roadster Reserve

Posted by richard_mills at October 31. 2018

I have run out of fuel with my steel tanked Roadster with main and reserve standard type taps. With both turned on I could not get anymore fuel into the carbs but I could see plenty left in the reserve side of the tank. Leant the bike over as far as I dare but none went over!

Got fed up with standard and similar taps leaking and therefore change to two BAP taps without standpipes ; one can use reserve taps or main taps because the standpipes can be pulled out after unscrewing the filters. Have got BAP taps on a number of bikes and never had any leaks......... yet!

This arrangement frees up a lot of extra fuel but I keep an eye on the mileage since refueling and refill soon after 100 miles has passed. On a tip I saw on the Access Norton website, I fitted a 'knitting register' on the choke cable to record the mileage reading when refueling. If, like me, you have never heard of a knitting register then look them up on eBay. Only problem was to get a size which would go over the cable nipple but not be loose on the cable itself; heatshrink tubing or pvc tape is useful here.  If only Norton had fitted a trip odometer; too expensive I suppose.

 

Re: Roadster Reserve

Posted by gary_painter at October 31. 2018

I'm pleased to hear from another advocate of two reserve taps. This is obviously a simple way to make the most of the meagre Roadster capacity.

My Ducati Monster also has about a 100 mile range, so I rely on the trip heavily.

I was lucky enough to find a lovely pair of pristine clocks for the Roadster at a bargain price from far off Pheonix, Arizona. (not much damp in that part of the world!) When they landed from across the pond, I was a little disappointed to discover that a trip meter is not standard equipment on the '72 green blob instruments. So thanks for the heads up with the Knitting register.

I notice that they only record two digits, which should be enough, but if four are required then it's just a matter of fitting two registers.

They come in lots of colours too, so should be able to co-ordinate with the bike.... Good call Richard. Thank you.

Re: Roadster Reserve

Posted by mark_savage at October 31. 2018

Previously gary_painter wrote:

I think we'll ALL run out of petrol in 200yrs John. I think you did well really..

The tunnel must be configured differently on your TR6 for the fuel to level out to that extent. Thinking about it most bikes have a more acutely angled top tube than a Commando, which extends much further back than normal and lies flatter. That makes most tunnels low enough at the rear to need a stand-pipe to form a reserve. The tunnel on the Roadster does seem a lot deeper than I've seen on other bikes and doesn't drop away much at the rear either, hence my thinking with a "natural" reserve.

However you did get me thinking how the fuel sloshes around in there, and I concluded that most of the surge is going to be back and forth from braking and accelerating. So the fuel can quite easily level the sides when it's all up the back end, but hopefully to a lesser extent on the Roadster with it's high tunnel.

 

Mark, thanks for confirming my thoughts. You obviously though along the same lines as me and tried it out. Pleased to hear that it works. How far do you get on reserve in this configuration?

I wouldn't know how far you could go until it ran dry and hope not to find out but I had to do about 10 miles to the next petrol station once. However in theory the amount left on my reserve side won't be any different to the amount that would be available If I used a main tap instead of a reserve. it's a small tank I try to top up in plenty of  time anyway, the extra available fuel due to two reserve taps is rarely called upon in reality.

Re: Roadster Reserve

Posted by david_broadbent at November 20. 2018

Gary, I think the fuel tap suggestion is excellent! Have you got around to it yet and if so, does it work in practise? Presumably you can now see the main tap side empty when you need to open the reserve side?

Dave

Re: Roadster Reserve

Posted by gary_painter at November 20. 2018

Thank you Dave.

Sorry to say that I haven't tried the idea out yet, as the Commando is going to be a very long project, though it might see the road some time next year.

Mark and Richard above, seem to have tried it with success and I see no reason why it shouldn't work, I will certainly be giving it a go. To the extent of carrying a petrol can with me on one of the first rides, to see just how far the reserve takes me.

 

I assume you would be able to see the level in the right hand side of the tank, but I'm not sure many people look to see if they need to switch to reserve?

It usually goes rather quiet when you need the reserve! So just a matter of reaching down and turning on the relevant tap whilst still rolling and she will soon sputter back into life.

Re: Roadster Reserve

Posted by marcel_walti at November 25. 2018

Hello

have a Roadster Mk3, I tried it with two reserve taps, the range after one half was empty and I opened the second half was about 5 km (road with some curves), therefore I went to the original configuration with a main and a reserve tap, that will last about 30 km

Regards Marcel

Re: Roadster Reserve

Posted by christopher_winsby at November 26. 2018

I thought you used to be able to get taps with two positions main and reserve but have not been able to get them. I have had similar problem, I have a Lyta tank. Using a main tap gives a short range before the reserve is required and two reserve taps does not give much reserve range. On longer journeys I carry a 2LTR reserve can or larger.

I use Bap taps from Andover Norton having the filters fall of other taps, they were brass filters soldered together then glued to the brass taps.

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