Ram-Air intake.

[andyinchville1]

Good point I didn't think about the fuel float limiting the fuel.....how would pressurizing the entire carb help in light of the fuel float still?
Andrew

 

[jpilot]

Good point I didn't think about the fuel float limiting the fuel.....how would pressurizing the entire carb help in light of the fuel float still?
Andrew

Float-type carbs depend on a difference in air pressure to draw fuel from the float bowl, through the fuel metering jet(s), into the throat of the carb. The pressures of interest are the air pressure inside the float bowl and the air pressure in the throat of the carb. The float bowl is vented to the atmosphere so the air pressure in the float bowl is the same as ambient air pressure. The air pressure in the throat of the carb (when the engine is drawing air through the carb) is less than ambient air pressure due to venturi effect. If you force air into the throat of the carb, the pressure in the throat will be greater than normal while the pressure in the float bowl remains the same resulting in a loss of pressure differential and, consequently, a lean mixture. Force enough air into the throat of the carb and fuel flow through the metering jet will be zero, but you're not likely to get to that point with a simple ram-air setup at the speeds we get out of these motored bikes.

If you enclose the whole carb in a pressurized plenum, that pressure differential that the carb depends on to draw fuel through the fuel metering jet is maintained since the float bowl will be vented to the higher pressure inside the plenum.

I hope that answers your question.

 

[mnbiker]

BTW what kinda damage can come from overrich?

might get a little residue in the engine but at most just fowl a plug.

 

[smitty]

Zowie! All this information at my finger tips! I love this forum.

 

[reddbak]

Air Force 1?

Awesome scoop mate!

I'm fabricating a cold-air induction tube from the shell off a yabby-pump and running convoluted ag-pipe to the carb on the 50cc unit.

 

[Ghost0]

Just a tip from someone with some wind tunnel and fluid dynamics experience. You should remove the front section of your intake. The widened opening that you have created is actually decreasing the amount of air that your carb sees. What happens is you are trying to pack air and that doesn't work. Your goal is to increase the amount of air pressure that your carb air intake sees. To do this you need to go from a high velocity low pressure opening (small) to a low velocity high pressure area (large). I would say your middle section is good and it does go into a larger section at the carb. If you just take off the large area at the front of your system you should be in good shape. Since these carbs are so small I may actually try making the initial opening of you intake even smaller. I posted a picture of a proper air box off an F1 engine. Notice it goes from a small size to a large size.

 

[JemmaUK]

Just a thought but why not use the blower bentleys system...

a carb (standard float) bolted to a blower in turn bolted downstream to the intake of the engine/manifold.. saves the problem of pressurising the carb...

Jemma xx

 

[Dave.B]

modify an angle grinder with a fan, that would have the rpm to make a difference wouldnt it?