Iced Carb remedy? (Pictured Story)

[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

[a10gf]

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