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Milky residue on slide and in carb 05 yz 85

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Hey guys any ideas what's going on with this milky residue, I have been playing with the needle and air screw cuz it was to Rich but now I'm getting this milky residue. It's a humid day we pooring rain earlier so there's deffs moisture in the air.

any help thx 

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I have a similar issue on an rm125 and I think it is moisture coming through the air filter. Worse on humid days and after washing and not covering air filter well.

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This topic is worth revisiting during spring and fall when temperature and moisture swing throughout the day.

1. When a vehicle has been sitting overnight, the entire intake system is below outside temperature.

2. When humidity is high, even a slight lowering of temperature can result in condensation. If there is dew anywhere else, one can also find it in the intake system.

3. People forget about the heat of vaporization of gasoline. Before and during WWII, it was common for that evaporation to cool aircraft carburetors below the freezing point of water. As gasoline was evaporating , water was condensing and freezing within the carburetor, eventually causing it to malfunction. By the time it was inspected, the ice would have melted and heat conducted from the engine might even have evaporated the water. The military was aware and was gradually replacing plain carbs with heated ones. A freezing carburetor possibly caused the death of bandleader Glen Miller. https://www.warhistoryonline.com/war-articles/proof-glenn-miller-rafbomb.html

4. The problem is not unique to a specific carburetor or even to carburetors at all. No carburetor type and no type of fuel injection changes either the amount of heat required to evaporate gasoline or the amount released when water condenses or freezes. Fuel injection just does not have any critical moving parts near or past the point where gasoline meets airflow.

5. The kind of gasoline does matter somewhat. A higher proportion of components with boiling points below that of water cools more and causes more condensation. Relatively little of those components may still cool the system but may not cool it below the dew point at all. That is always a production compromise because components with higher boiling points (such as ethanol) may not vaporize even when well atomized or may subsequently condense against metal.  Is that not the behavior that we expect from the premix oil?

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