Well, I'm shocked.

I stand correcteded.

 

AIUI, carb icing is caused bt the temperature drop from the petrol
evaporating. It's certainly got nothing to do with windchill, as
evidenced by the fact that you can get it while the bike is
stationary.

 

I thought it was caused by the pressure drop in the venturi. (There's
still a 'wind' in the carburetificator)

 

There would be _some_ evaporation going on, but yes, the expansion of
the mixture due to the pressure drop would cause the more significant
cooling effect.

 

I wonder why I've never suffered from carb icing.
Perhaps some bikes are more prone to it than others.
Or perhaps it's because my throttles are WFO all the time. ;-)

 

Erm no.
Carb icing is caused by the pressure drop as the air passes through
the venturi of the carb.

 

Half the problem (ime) was that the carbs wouldn't ice up at constant
speeds, it'd happen when you'd been giving it **** across country then
had to slow down for a village or it'd be fine if you were just
ambling through town but as soon as you opened it up on a faster road
the carbs would ice up.

It did seem to improve when I changed from the normal air filter to a
K&N one on my 9R but that might have been coincidence or the fact that
I stopped commuting on it at about the same time.

 

No. AIUI it's more likely to happen in high-flow situatins, no less.

 

There are sevral factors involved.
1) Fuel injected systems do not have a venturi so dont suffer icing.
2) Small bore carbs are more prone than larger bore types but give
better fuel economy.
3) Intake air temperature is affected by location, often pulling air
which has been warmed passing the engine.
4) Carb body temperature is affected by both location and mounting
method.

 

Every day's a school day.

 

Actually, it's caused by the temperature drop as the air expands
coming out of the venturi.

 

Good attempt. Must try harder.
The air will still be cooled as the pressure reduces through the butterfly
but warm petrol squirted at high pressure from an injector will not be affected.

 

I tried to keep it simple but .....
The increase in velocity through the venturi causes a pressure drop.
Not as simple as it might first seem.
Plenty of room for pedants in this one <B

 

Well I'm gonna claim at least a partial whoosh.

 

Indeed. I wonder if he thinks he's got away with quoting other
people's ideas as his own?

 

Takes heat to evaporate [1] fuel - the heat has to come from somewhere,
the carb body, the air passing through, and the temperature drop causes
moisture to condense out and freeze.
Nothing to do with 'windchill' as we know it from riding along, although
a case could be made that an unclothed human can be regarded as a
carburettor, but that would be silly.

[1] The purpose of the carb is to atomise the fuel, but evaporation
takes place also.

 

Nah. I can buy one for the Scim.
It's likely the particular method that Ford use that's patented, as
electrically heated windscreens are older than Moses, and older
technology might be more expensive and/or less reliable than the Ford
way.

 

heh

 

The 9RC2 had a recall due to the carbs icing. A man in a garage "did
something" and I got a certificate and everything.

 

Actually, it's not that complicated.

Indeed: what do you mean by pressure?