Bing needle - settings

[atoyot]

I understand that my 1977 40+ with a Bing carb will run on 10:1 thru 25:1 with no adjustments. Right now I'm keeping it on the rich side of that mainly out of, I don't know, tradition perhaps, or just a bit of caution. When I had a Featherweight a few years ago it was converted to 25:1 by swapping out the needle which, as we know, is a mm or so longer, and with the same taper along the same distance from the tip as the original. I measured and compared them....

Upon cleaning out the carb, as the engine's new to me, I notice that the throttle needle has several slots by which a keeper ring of sorts holds the needle in place. Moving the keeper ring to allow deeper needle penetration into the main jet is apparently the same as swapping for a longer needle in the other models. Has anyone played with different adjustments, or positions, of the needle in a Bing carb?

I know, "if it ain't broke, don't fix it" and this engine runs just fine other than firing only every alternate rev or less at under 1/4 throttle or so like my Featherweight did; model airplane people refer to this as "4-stroking" which is caused by an excessively rich fuel mix. That's apparently normal for a low-speed running Seagull. This is mine - http://www.youtube.com/watch?v=cfjpVoazL2Q

I, however, was born to fiddle with things uncontrollably. I tried 3 of the 4 different needle-to-clip positions on mine today just to witness what change might be seen. I can't say I noticed enough difference to tell. The needle's a good bit pitted and pot-marked from corrosion and probably ought to be replaced and so one wonders if that damage makes the height settings less relevant.

Another thing - this needle is a bit sloppy or loose-fitting as it hangs from the throttle piston unlike the Villers carbs, in which the needle is fixed pretty firmly in place.


Thoughts?

[Waggles]

Firstly I have to say I don't have any experience with the Bing carb but am commenting generally, am sure someone with more knowledge will be along shortly.

Certainly with the villiers carb raising and lowering the needle with the screw adjustment can make quite a difference, when I converted by 40+ I found at the standard setting it would do little but 4 stroke, 1 1/2 turns down and all is well, I believe Vic of this forum has a motor that needs the needle even lower than that.

I certainly think the 'loose' needle and corrosion can only hurt performance but obviously not by much! If the needle isn't central I would imagine the spray of fuel might be a little off centre but probably doesn't affect the amount of fuel sprayed so thats probably why it isn't making any difference perhaps?

Could it be the needle on the bing has much less of a taper on it? if so the height adjustment won't have as much affect?

[atoyot]

Thanks, Waggle.

Recall that the Villers needle has a flat top the diameter of the throttle piston's little "well" of sorts, that keeps the head centered perhaps 6 to 8mm above it's exit hole as it presses upon a spring. That is, the exit hole for the needle at the bottom of the throttle piston and the disc-shaped head of the needle work together to keep a Villers needle straight in line with the fuel jet opening. Add to that, the screw plug overtop of the needle and its flat bottom. There's plenty to stabilise a Villers needle.

The Bing needle presents through the hole in the bottom of that carb's throttle piston with no extra support for central location as such. My assumption is that the velocity of the fuel being sucked along the jet walls past the needle force the needle to remain centered, much like the ball inside a rotameter is kept from the walls of that device. So, interesting as the wobble is, it may not be abnormal at all now that I consider it for a while.

The slope of the needle isn't as dramatic as I recall seeing in my Featherweight's Villers carbeurettor, though it's been a few years.

See the diagram below, and how the Bing needle (#19) is kept in place by means of a circular clip (#4) that pinches the needle along 4 possible slots (not visible here), much like piston ring slots one above or below the other. The circular clip is pressed upon by another ring (#18) underneath the return spring (#17).



A limiting factor in my "tests" is that I was running the engine in a rather small test tank, and not out on the water. Easy as it is to adjust, I'll have to fiddle with this a bit next time I take this somewhere. It's only a matter of curiosity at this point though if I can get it to run more smoothly at an even wider operating range, that has to be good in some way.

[Waggles]

Interesting.

Pardon my ignorance ( never had a chance to look at one of these carbs ) but I note it has what is basically a similar setup to a villiers or a 416 even, but the body seems to have a second 'barrel' but without attendant jet etc, whats that all about then? could that be something to do with why the carb runs on such a wide range of mixtures? does it compensate in some way?

[atoyot]

I see what you're speaking of, and looking at the diagram it would look like a second barrel. In life, it's just a closed cavity with no holes, passages, vents, or anything for it. There's no apparent need for this except possibly for structural support.

That is, the top cap needs solid meat for screw bosses which are provided in the wall between the piston cavity and this mystery cavity; my guess is that the remaining chamber wall gives balance of downward pressure for the top cap when screwed down almost mid-span of the top cap.

This is only a guess of course.


--ted

[Waggles]

Strange design!

I think, going back to the original question that the needle position doesn't make much difference due to the taper on the needle and / or design of the jet carrier.

I was just sitting here wondering how on earth the carb could cope with such a range of mixtures when it dawned on me, CAN it actually run OK on 10:1? I have my doubts. If you look in the ID section of the main site I note that the Bing carb was only used from 1976 at the earliest ie very close to when ALL gulls were set to 25:1 ( 78 ) if you read the FAQ on running on 25:1 it says Bing carbs are OK on 25:1 as are later Amals ( 416 etc ) 'as they were set to 25:1 at the factory' I think this means that all Bings are 25:1 carbs NOT ( as could be implied ) that they work at 10:1 but you can switch to 25:1 without adjustment. I mean I wouldnt attempt to run my 90 with a 416 on 10:1 thats for sure!

[atoyot]

Hi, Waggles.

That's about the most rational theory ever and it makes perfect sense. That is, as rich as these things seem to run even on the suggested Villers needle setting and the traditional fuel/oil mixtures, those engines with a 25:1 carb and burning 10:1 probably just leaned out nicely.

Oh, you'll like this somewhat related accounting: I took a "new" to me boat [1980-something Harpoon 5.2] to a friend's place yesterday to use his pressure washer on it. The Briggs & Stratton 4-stroke started up just fine, ran for probably what was a float-bowl length of time and then flat out quit running. We choked it again and it ran fine, on half choke. We figure we must have dumped in some older oil mix from one outboard or the other, and what do you know? Too lean a fuel for the way this engine's set up (for plain fuel of course). Who knows how much oil mix was added to how much regular fuel already in there at the time? It's an example of how adding just 'some' oil in the gasoline/petrol affects the viscosity and all that. It couldn't have been terribly much considering the exhaust was not very blue or smokey, in the bright sun that is.

Thanks for sharing ideas back and forth on this. It's really easy to over-analyse some things and your suggestion works for me.

- Ted

[John@sos]

Hello Both, think the idea that they may have been on the cusp of changing to 25:1 might have some merit!

Sadly for those who bought them in 1977 Seagull insisted the mix was 10:1, so I wonder if they ran very lean but made loads of smoke, so they never noticed!

The needle has three settings and the normal is the middle, but one up would weaken it, and one notch down richen it, so a little adjustment. I have run loads of Bing Carbs and they would appear to be better in many ways to the conventional villiers, but sadly today few spares are available for them.

The float bowls are no longer available, and these do break.. the latest part to dissappear is the Air compensator cover, so protect your Bing from knocks and wire the cover on!

Regards,
John
SOS

[Waggles]

Well there you go and some sensible tips!

I think in general most people have the idea of adding more oil to protect an engine not realising it leans the mixture out. ( Not heard of it on 4 strokes though Ted ) this isn't helped by more modern practices, My M*riner 2 strokes instructions say run it in on 50:1 then switch to 100:1 No doubts the extra oil helps of course but you have to make sure the mix is OK too. I guess Gulls are not so sensitive obviously if the Bings run @ 10:1 !!!

Personally I run the M*riner at 50:1 all the time ( I'd like it to last a little longer than 5 years and the plug colour shows a good mixture ) and my 40 runs at 20:1 but I have adjusted mixture which was too RICH with standard 25:1 needle mounted flush so I know its OK.

Know what you mean tho, I too am a born Fiddler! I HAVE to know how something works or I am not happy!

Look after that Bing Ted

[smutts]

I know, I know, old thread, follow the link and click on "type 10", that gives some generic info on this carb.
http://www.bingpower.de/en/service/data-sheets/

I notice that as found, my 1977 forty plus had the needle set 3rd notch from the top. With oil at 20:1, This is rich as hell slow speed, and four strokes a plenty. Shut the fuel tap and it runs the same, then speeds itself up running really nicely for a few seconds before dying when the bowl's empty. This suggests the mixture is rich, passing through a sweet spot as the fuel level in the bowl lowers towards empty. So I will be fiddling with the needle at some point.

How dependant are seagulls on fuel cooling? Like chainsaws and such like?

[John@sos]

If you have a Bing carb it should be running on a 25:1 mix. If you put more oil in than 25:1 it will replace the petrol and the motor will hunt, unless you raise the needle. But as they run well at 25:1 so why bother.

They have to be on 2T for outboards though.

As for cooling by mix, well they must be some, but noone has ever tried to figure that one out before.

Since this thread was started I can now get most of the parts for Bings, except the air intake covers.. those, if you have lost it, you have to make up from a bit of thin ali plate, formed over a wooden block and with 4 small bits of ply glued in with sikaflex or similar, so the air can get round the corners and into the intake but water is kept out.

I can even get float bowls again, 2016 price £12.50!

Regards,
John
SOS

[headdownarseup]

I've had a little bit of experience with Bing carbs before now, and as John says, the middle position on the needle will do for most applications.
I have a few 40 models in my collection both old and new and most of the villiers carbed motors will 4stroke to some extent at low rpm's. At higher rpm's the motor tends to run much better as more load is put onto it. There's not really a lot of adjustment possible on the Bing carbs except for the needle position and that's about it. I wouldn't be too worried about a small localised area of pitting, as long as the carb is well cleaned and free of debris it should perform quite well. Don't forget both of the fuel filters, one in the fuel tap, the other in the carb body where the fuel line attaches. Blocked filters wont help much either.
Might be worth trying a 25:1 fuel mix too. As far as fuel cooling goes, never heard that before? A rich (or over fueled) engine will tend to run a bit cooler and possibly foul the plug a bit quicker, whereas a weaker (under fueled) engine will run much hotter. The trick is to get the engine running smoothly enough throughout the rev range with adequate fueling all over. Looking at the colour of the plug should help determine what's going on with the engine's fuel requirements. Basic stuff really.


Jon

[Charles uk]

Pistons are cooled by 3 methods,

Conduction through the oil between the piston body & through the rings to the water cooled cylinder walls.

Through the cooler fuel/air mix as it passes through the transfer port & over the deflector on the piston crown.

And through vaporisation of the fuel particulates in the fuel/air mix, which happens on all the warm / hot parts of the engine internals leaving the oil which does not vaporise, to lubricate all the moving parts.

Un vaporised fuel does not burn as fast as fuel vapour, one of the major reasons why 2 stroke motors run better when hot.

I have sent a few Seagull pistons off for analysis to find the silica content & still waiting for the results, so as to establish a safe maximum working temperature for my racing Seagulls.

So to summarise, a lot of the piston cooling in a 2 stroke is from the fuel.

[John@sos]

Who says we are too old to learn!

Thanks for that Charles, never knew!

Regards,
John
SOS

[headdownarseup]

I still like to "read" the plug after every couple of hours use just to satisfy myself all is well. If you know what you're looking at it should tell quite a lot about what's actually happening inside.
I'm old skool after all, and like to fiddle. (keeps me out of arms reach of the missus for a while at least )

Jon