Iced Carb remedy? (Pictured Story)

[MG]

C'mon, don't be so damn logical!   

[a10 gf]

MG, correct about the "Kondensfjerner". Used in periods of frequent temperature changes, which may produce water condensation in the tank. AFAIK, this alcohol based additive breaks down water into much finer molecules and 'mix' it with the fuel into something the carb\injection does not mind too much, thus getting water out of the tank and fuel system. Seems to me the now common use of plastic material tanks on cars has lessened the need for this.

The additive will help starting\carburation\combustion, but not any frozen\sticking carb throttle.

Erling

[MG]

a10gf, the problem is the vaporisation of the fuel in the carb, which absorbs energy from the surrounding atmosphere, therefore cooling the carb further down and causing the water to condensate and finally freeze. If the water is bonded in the fuel it will not condensate and therefore simply not freeze and ice the carb. That was the mechanism I had in mind.
The carb or injection systems can deal with rather large amounts of water in the fuel, the problem that occurs are the ice crystals blocking nozzles, slides, etc.

[LJ.]

Thanks for the replies lads... although the problem wont be occurring too many times on the A10 as I'm using my M21 more so in the conditions due to the salts on the road, but an interesting problem never the less.

I think I'd prefer to go along with an external remedy rather than additives to the fuel, the unleaded fuel is crappy enough as it is. Triton Thrasher makes a good comment in removing the tufnel spacer and if the A10 was my daily transport I'd remove it until summer comes around. I wonder how they coped with icing on the carbs during the sixties? maybe most people had only short journeys to and from work then?

In a couple of days from now I'll be setting off on my journey to the Dragon Rally, to be held in North Wales. I'm wondering if I'll be getting icing problems on my M21, although I doubt it somehow as its a much hotter running engine, but, the carb is in the airflow and not directly behind the engine, it also has a thicker tufnel spacer. But then again I'm going to be stopping more often as there is no handlebar fairing so I'm going to be colder while riding. A full report back will be in mind on my return. Thanks again for suggestions.

[bsa-bill]

Neither my 61 or 59 A10 have tufnol spacers, It's not listed in my spares book either unless part No 65 - 232 is it, but is listed as a gasket and apparently uses two.
Strangely these are shown as fitted between the drip shield and the carb, hardly required I would have thought with an o ring in monoblock, also there are no A10  gaskets shown between the dripshield and the head only for A7 and A10 S/R.
Misprint in my spares book maybe,
Also I note different part numbers for Dripshields for Alloy heads and cast heads.
Sorry this is getting away from LJs BirdsEye carb

All the best - Bill

[MG]

Bill - the tufnol spacers should prevent the heat from the head to be transferred to the carb and hereby lowering the performance of the engine (heated air contains less oxygen per volume unit due to it's lower density). I suppose they are some kind of aftermarket-mod, quite common though.
The dripshield for manual advance mags are recessed to stay clear of the advance lever cable, which is not necessary for the auto advance mags. Maybe this explains the different part number for the sports models with the alloy head. Just a guess.

[bsa-bill]

Thanks MG
 I have a thick (3/16 ) fibre washer between head and dripshield that I rasped to a wedge shape to make a bias washer type thing, convinced myself that it helps a little, might be rose tinted thinking though

All the nest - Bill

[a10 gf]

Getting rid of water residue in any fuel supply to any engine is a good thing, and a small dose of alcohol in the tank now and then does the job. Every gas station in the whole country here sells it.

As for LJ's sticking throttle problem, needs anti-icing lubrication of the carb body to help the throttle sliding properly, I'd say nothing at all to do with fuel.

[muskrat]

G'day all,
            when I lived in the bush I would use a cap full of metho in the generator or chainsaw to help with water in fuel problems. One for the tank, two for me.
When racing at Eastern Creek running methanol the carbs would ice up at the end of the straight wide open. A bit scary going into turn one at 200k's so i would hit the kill button for a few seconds and they would free up. So I figure it's not so much as water in the fuel but condensed water on the outside freezing the carbs. It never happened running petrol. Motors run a lot cooler on alcohol.
Cheers

[LJ.]

After a very cold past six days riding I've had no problems at all with the M21, and I was watching most of the time. Seems just as I thought, that with a hotter running engine I'd not have any problems.

[Josh Cox]

L.J.

The problem you are having with your carby is a very common one, especially a concern in aircraft, go talk to your local flying instructor, he'll probably be able to show you the skids mark in his undies due to icing issues.

With the operation of a carby, there is a low pressure inside the throat of the carby (sucking of the engine), when you decrease the pressure of a fluid ( air in this case ), it lowers the temperature of the air mass, when you are at high relative humidity and lower temperature, ice can form in and even block the throat of a carby, in and aeroplane this can be the start of a very bad day (hence the skid marks).

If the problem you wish to solve is:

1) the visible ice in the carby body, spray it with CRC, Lanox or similar, this will stop the ice bonding to the body,

2) loss of power due to blocked carby, have a small tube in the throat of the carby sucking hot air off the exhaust, this will increase the inlet temp of the air and perhaps avoid/melt ice, but this will decrease the density of the air, i.e. less power at the back wheel.

Heating the fuel is another option, but in my opinion you'd need balls of steel to try that one, what's the flash point of your fuel, I would not want to find out.

[dpaddock]

Well, if you have water in the fuel it will go to ice around 0 degC in the tank and/float chamber. It will therefore never get to the air stream.
As pointed out here elsewhere, it's moisture in the air that's the culprit. The air temp in the choke drops as its pressure drops because of the venturi effect, and produces ice. The only solution is to heat the air above that ice point as it enters the carb. Not too easy to do, but perhaps deflectors could fitted, as suggested.

David