Odd carb phenomenon

[11Rider]

Hi guys, while diagnosing a carb problem today (turned out to be a leaky, gas filled float) I noticed something that I've never heard discussed before. With the air filters off (I run pods), when you blip the throttle the #1 and #4 carbs shoot out a mist of some sort for a split second. The 2 and 3 don't. Bike runs perfect now that I fixed the float so I don't know if this is abnormal or not. Anyone notice this before??

[Rasputin]

Myself I have seen mist spit back from various carbs with me playing with them. I can not recall if it was a paired problem or not.
Just a couple of thought out loud her but I would check the valve clearances, and the ignition coil for 1+4 in case it is mis-firing. If you have the Jardine spaghetti pipes like I have on a couple of my bikes then I would suggest exhaust may be partially plugged. Of course the simple answer may just be in the carb settings themselves.

[JeffH]

mist of some sort for a split second. Anyone notice this before??

What was the Air Temperature and Humidity at that time?? Likely what you were seeing as you blipped the throttle was Condensation of Air as the air accelerated into the venturi. Same phenomenon as air gets sucked into a jet engine intake or the 'cloud' that forms over the wing of an airplane especially when in a high lift configuration. Just more prevalent in certain temp/humidity climatic conditions. That's what I'm guess you saw. In fact, I recall seeing an XS11 You Tube about tune ups that recorded the same thing as the momentary throttle rev caused the air vapor to condense and become visible in the Carb Intake.

Jeff

[crazy steve]

That's not that uncommon to see with individual runner intakes and/or short intake runners. Your 2 & 3 are probably doing it too, maybe just not enough to see. I would check the valve clearances to be safe, and some careful carb tuning could probably minimise it....

[Rasputin]

What was the Air Temperature and Humidity at that time?? Likely what you were seeing as you blipped the throttle was Condensation of Air as the air accelerated into the venturi. Same phenomenon as air gets sucked into a jet engine intake or the 'cloud' that forms over the wing of an airplane especially when in a high lift configuration. Just more prevalent in certain temp/humidity climatic conditions. That's what I'm guess you saw. In fact, I recall seeing an XS11 You Tube about tune ups that recorded the same thing as the momentary throttle rev caused the air vapor to condense and become visible in the Carb Intake.

Jeff

True enough but why would it only be on 1+4 then? I am learning as I go so bare with me here.

[11Rider]

Good thoughts guys. Now I'm concerned about my intake valve clearance but the bike only has 8k miles on it. The humidity was very high today, but I could feel that the 1 and 4 carbs would shoot air/vapor backwards whereas the two middle ones definitely did not. Every blip, exactly the same results.

[JeffH]

Your 2 & 3 are probably doing it too, maybe just not enough to see. I would check the valve clearances to be safe, and some careful carb tuning could probably minimise it....

+1 agree

I will try and find that You Tube video. I looked at it a dozen times because the way the 'cloud' formed in the Intake it gave the optical illusion that the vapor was coming Out. Actually it just formed and disappeared as the Air rapidly accelerated as the Carb momentarily opened up. Disappeared as quickly as it Appeared. At the moment of 'the vapors', did you smell raw Gas???

11Rider confirmed "Humidity was High today". I think this Cloud thing is what you were seeing. Why just 1-4? Well 2-3 are in the middle and things are hotter so it takes more for the air to condense. 1-4 and in free air. If the bike ran real lousy then I'd think maybe there was something wrong. However if it is running great, sounding great with good mpg then I'd be a little reluctant to tear into a maintenance project based on what you saw today.

Jeff

[Rasputin]

+1 agree

I will try and find that You Tube video. I looked at it a dozen times because the way the 'cloud' formed in the Intake it gave the optical illusion that the vapor was coming Out. Actually it just formed and disappeared as the Air rapidly accelerated as the Carb momentarily opened up. Disappeared as quickly as it Appeared. At the moment of 'the vapors', did you smell raw Gas???

11Rider confirmed "Humidity was High today". I think this Cloud thing is what you were seeing. Why just 1-4? Well 2-3 are in the middle and things are hotter so it takes more for the air to condense. 1-4 and in free air. If the bike ran real lousy then I'd think maybe there was something wrong. However if it is running great, sounding great with good mpg then I'd be a little reluctant to tear into a maintenance project based on what you saw today.

Jeff

Good possible explanation Jeff. I love this site for all of it's informed people. Thanks.

[11Rider]

Yes, very convincing and plausible explanation - thanks! Definitely was not gas so I'll go with the "cloud" idea.