Anti-ThermoQuad? - Page 3 - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

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post #21 of 29 Old 04-30-2019, 02:04 PM
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A propane torch used on the base of the down-draft single barrel carbs on my 1951 Willys wagon & 1955 Chevy 3100 pickup worked every time.
They both had the wire mesh oil bath air filters. (Could this have extra chilled the incoming air?)

After changing the Chevy to a K&N, I don't recall carb icing happening again. But it was no-longer my daily driver either.

pdwestman
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post #22 of 29 Old 04-30-2019, 02:12 PM Thread Starter
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Quote:
Originally Posted by pdwestman View Post
A propane torch used on the base of the down-draft single barrel carbs on my 1951 Willys wagon & 1955 Chevy 3100 pickup worked every time.
They both had the wire mesh oil bath air filters. (Could this have extra chilled the incoming air?)

After changing the Chevy to a K&N, I don't recall carb icing happening again. But it was no-longer my daily driver either.
Never say never, but I canít imagine how either an oil bath or oiled foam air filter would affect carb icing. Unless the oil film that these salve on the inside of the carb was enough to let the ice gradually stuff off and go through the engine rather than build up inside the carb. Pure speculation here though.

I believe that by far most of the chilling of the air is from the evaporation of the gas and secondarily from the pressure drop through the venturi. That is why part throttle tends to cause icing when full throttle will not.

Carb icing is a very complex process with many variables so I think it is nearly impossible to generalize.
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post #23 of 29 Old 05-01-2019, 04:38 PM
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Is it the same principle as when you drain the tank on your air compressor and the nozzle frosts over ?

Never pick a fight with an old man.. If he's too old to fight, he'll just kill you..
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post #24 of 29 Old 05-01-2019, 05:25 PM
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Is it the same principle as when you drain the tank on your air compressor and the nozzle frosts over ?
Yup, pretty much that same thing. Or tire valves after seating the beads.

pdwestman
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post #25 of 29 Old 05-01-2019, 05:28 PM Thread Starter
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Is it the same principle as when you drain the tank on your air compressor and the nozzle frosts over ?
Yep. And the same principle that allows refrigerators and AC to work.
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post #26 of 29 Old 05-01-2019, 09:12 PM
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Is it the same principle as when you drain the tank on your air compressor and the nozzle frosts over ?
As my chemistry teacher used to say, "It is your friend the ideal gas equation PV=nRT"

Pressure x Volume = Amount x Temperature (R is just a constant to make the units work)

The carb causes a pressure drop resulting in a temperature drop.

Good source material from AOPA as well.

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post #27 of 29 Old 05-01-2019, 09:25 PM Thread Starter
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Originally Posted by jncdi View Post
As my chemistry teacher used to say, "It is your friend the ideal gas equation PV=nRT"

Pressure x Volume = Amount x Temperature (R is just a constant to make the units work)

The carb causes a pressure drop resulting in a temperature drop.

Good source material from AOPA as well.

jncdi
Yes, but this is the smaller contributor. The main culprit is the heat of vaporization of the gasoline. Together though, they can wreak havoc in the right conditions of temp and humidity.
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post #28 of 29 Old 05-01-2019, 10:26 PM
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Adiabatic expansion process = cold or ice.
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post #29 of 29 Old 05-11-2019, 12:30 AM
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[QUOTE=Tom Schmitz;683123]This is an interesting article that frames the problem from a light aircraft perspective. This quote from the article:

"In reality, certain situations are considerably riskier than others. Icing is most likely to occur—and to be severe—when
temperatures fall roughly between 50 and 70 degrees F and the relative humidity is greater than 60 percent."


I don't know anything about carb icing. In fact, I never heard of it before I read this post. However, I can tell you that here in Adelaide, South Australia, the temperature and humidity range mentioned by Tom are the norm during late Autumn (now) and through winter and early spring.

The current conditions in Adelaide are: 16.2 Degrees F and 70% relative humidity. As we get into winter, which begins officially in June in the Southern Hemisphere the temps will drop more towards 50 degrees F as maximum temps during the day. These conditions would be typical for a the large proportion of the Australia Population that live in the southern states.

So perhaps, if it's true that our winter weather conditions are conducive to carb icing, tt would support the argument that the AU carby set up is supposed to prevent carb icining

Last edited by timberfoot; 05-11-2019 at 12:36 AM.
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