What? Out of petrol? Consumption concern.

[CrispinA10]

 
Despite high winds just been out for a 20 mile spin on my new 1961 Super Rocket RGS replica. Ran out of petrol, fortunately about 300 yards from home. What's going on? I filled the tank (over three gallons) two weeks ago and have only done about 90 miles on that tank.
30mpg. Is that possible? I'm running in, so have never exceeded a third throttle and not topped 60mph yet. The tank wasn't empty, I should add - rocked it from side to side to try and eek a little extra out and I could hear it sloshing. There are two lever-type taps. I had assumed one was a reserve, but not sure. Whatever, neither allowed any fuel through until I walked home and returned with half a gallon. I tried tickling before filling, and nothing. Filled, tickled and kicked and it roared into life. Should one be a reserve with a lower level? Whatever, surely it shouldn't be using fuel that fast. Plugs are sooty all over thread and electrode, although core is healthy chocolate. The bike seems to be running fine - air lever fully open when warm and I'm not using the advance retard yet apart from starting, partially because I'm scared of it. The builder made a mark in red paint on the "safe running" setting I and I leave it there while running.

[Topdad]

Know its obvious and excuse in advance but no leaks ? particularly when standing ,do you leave her on a side stand and moving onto anther recent post does the oil smell of petrol . Mine does 55-60 to a gallon not going mad but keeping up with the traffic, so its a bit excessive to say the least, best of luck, Bobh

[Triton Thrasher]

Yes one tap should have no pipe sticking up into the tank.

Normal riding is done at full advance.

There are mixture adjustments on the carburettor: idle mixture screw, needle position, different slides, main jet. Amal tuning procedure is in the manual.

Don't use an old needle jet.

Choked air filter also causes rich mixture.

[RichardL]

Crispin,

I hope it makes you feel better to know that I also ran out of fuel this last weekend, but not in as fortunate a proximity to home or other fuel. Thanks to GPS on my phone, I found fuel "just" two miles away. My wife was out of state, I wasn't going to leave it just standing on the side of the road, and I didn't want to pay about $200 for rescue. Temperature outside was just under 80 deg F. I started pushing, some up some down (about equal). For the first 3/4-mile I was still wearing my helmet and no one stopped to help (on a pretty well-travelled road). Within about an 1/4-mile after taking off the helmet (exposing my grey hair) a man and wife stopped to ask if I needed help. He was about my age and wearing a Harley- Davidson shirt. They offered to drive up the road to find gas and bring some back if the station had a gas can. Well, I had stopped pushing at the one remaining farm house along this industrial road to see if they would sell me some gas. No one home, but my new friends pulled up as I was walking back down the drive. They had bought a gas can and a gallon of fuel to get me on the road, as it did. I was really thankful, because another mile of pushing would have laid ahead. I knew they would not take money for the kindness. They just said "pay it forward."  [Now, this story does not compare with one that Richard (Orabanda) must be able to tell about running out of gas while riding 1/2-way out to the other side of his cattle station (or is it sheep?) and having to push his bike back 82 miles.  ]

After that, I plan to get the correct petcocks for having a good reserve on my 2-1/2 gallon tank. I was also running rich and, apparently, getting even worse than the 30 mpg I was expecting. Regarding the reserve, up until last Saturday I thought there would be enough on the other side of the tunnel to provide a couple of miles. Proved not to be the case.

Richard L.

[CrispinA10]

No leaks - no pong of petrol nor marks and stains. I do know a bit about Amal Concentrics, although am no expert, but spent a long time fettling the Enfield until needle, slide and jets were spot on (with a lot of help from Hitchcocks). What is odd about the Beezer is that the carb seems to set up fine by the builder, and it was checked by the bloke who sold it on (Eddy Wright of TT sidecar fame). It all looks new and I would be surprised if the needle and jets were not new. It was a nut and bolt rebuild and ticks over perfectly. Yes, it's full advance on the lever while riding. So I'm not entirely sure that it is running rich. There isn't an air filter to get blocked, and it's only done 150 miles since engine rebuild. Guessed (probably wrongly) that the light soot was due to running in and excess oil making it through the piston rings before they are properly bedded in. The centre core looks healthy enough - sort of chocolate brown, but there is a hint of soot. Because it is running so well I thought I would try hotter plugs, which have now arrived and I'll fit them tomorrow - Champion N5Cs.
If I am barking up the wrong tree and the bike really is running rich, I'll have to start thinking about the carb, perhaps raising the needle clip a notch as a starter. Apart from sooty plugs and dreadful petrol consumption, what are the indicators of really rich running? And could rich running really halve the fuel consumption?
I will also drain the tank and have a look at the levels of the tap tubes.
Many thanks for the suggestions.

[CrispinA10]

Richard, thanks for that - I feel almost guilty at having run out of fuel so close to home. The old A10 is a heavy beast and I wouldn't want to push one too far, particularly uphill. And certainly not 82 miles. Is that true? Flamin' Nora! Interesting though that you mention less than 30mpg while running rich - I think I had better pull the concentric apart and have a look tonight. I reckon it must be that. By dint of good fortune the old bored out Enfield has the same Concentric Mk I and I have a box of spare needles, jets and slides at the ready.
80 degrees? Blimey. It's about 55 here in Hernhill as the sun begins to sink and there's a chill wind whistling. But at least I'm not pushing a Beezer to a far distant cattle station. In fact I'm disappearing across the lane to the Three Horseshoes for a well deserved pint.

[Triton Thrasher]

A hint of soot isn't too bad, if it's what I'd call a "hint."

A rich needle height and/or slide cutaway and/or worn needle jet can get MPG down to low 30s, with apparently not too bad running.

[Ted_Flash]

Hi Crispin,

My contribution is: petrol theft.  Was she left unattended?

[CrispinA10]

Right. She must be running rich then. Nope, no chance of petrol theft. Locked away in Fort Knox style shed with alarm and CCTV and never been left unattended. So I'd better start looking at that concentric...seems like I'm underestimating the soot. I had assumed that smooth running meant properly set up carb, but very useful to know that it could well be far too rich a mixture. I'll start with the needle notches and see what happens.
Thanks for all the suggestions.

[muskrat]

G'day Crispin. If your running a concentric on an alloy head you may be having fuel level (float) problems. At that downdraft angle to get the right fuel height the float is touching (or almost) the base of the body. This will un-seat the needle causing a very rich mix. Fuel height for a concentric is between 0.170 and 0.240" below the body/bowl joint, measured on the side below the idle screw.
Cheers
ps. you need to make a tool out of an old bowl plug with a clear hose attached to check the height.

[RichardL]

The old A10 is a heavy beast and I wouldn't want to push one too far, particularly uphill. And certainly not 82 miles. Is that true? Flamin' Nora! Interesting though that you mention less than 30mpg while running rich .....

80 degrees? Blimey. It's about 55 here in Hernhill as the sun begins to sink and there's a chill wind whistling. But at least I'm not pushing a Beezer to a far distant cattle station. In fact I'm disappearing across the lane to the Three Horseshoes for a well deserved pint.

Of course it's true and it was 140deg F.!! (Well, maybe not, but I bet he's got some story like that, being out in the expanse of Western Australia.) My daughter's name is Nora and I could see calling her "Flamin' Nora". If it's not actually crude, it fits.

I wish I could go across the lane to the Three Horseshoes.

Richard L.

[duTch]

   If it has a reserve function, maybe it's blocked....?

 I run out occasionally, but the Gutzzi is a bit heavier than the Beeza ... get about 10K/Litre on both

[wilko]

Disconnect your fuel line from your taps and make sure they don't leak. Half of your fuel could have flowed into your crankcases.

[CrispinA10]

Some interesting suggestions, for which many thanks. I rode round to see a bloke in Herne Bay yesterday who is a BSA enthusiast (and Norton and Triumph and Harley) but has a fine pair of Gold Stars. He looked at the plugs and said that they do not show rich running and that the thin layer of soot is just fine - the core is chocolate brown and just fine and dandy.
He also reckoned that 30mpg isn't unusual, and that's about what he gets from his DB34s.
I could understand that more if I'd been thrashing it, but I'm running in, haven't topped 60mph in fourth yet and treating it very gently.
I don't think the reserve tap is blocked because I can see fuel flowing freely when I tickle carb, but that's worth investigating. Perhaps both pipes are too high in the tank - there was quite a slosh when I rocked it.

[Dynamo Regulators Mike]

60 mpg is closer to usual. Must be running rich. A small change in fuel level in the float chamber or air screw adjustment will make a big difference, especially running at those slow speeds.
Try running with one petrol tap closed. That ought to double it