Pop off pressure

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savageboy69

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Hello I run a g230rc in my 1/4 scale and I've been looking on the net and I hear a lot about pop off pressure and how a lot of the same carbs are all different as far as pop off pressure. Does any one know what pressure to run for optimal performance?
 
savageboy69 said:
Hello I run a g230rc in my 1/4 scale and I've been looking on the net and I hear a lot about pop off pressure and how a lot of the same carbs are all different as far as pop off pressure. Does any one know what pressure to run for optimal performance?
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What do you mean POP OFF pressure???????

whart type of carb do ou think about.

as far as i know there are noe pop off valves on the Walbro carbs.

to get the right information on thius subject ask the guys that talks about that pop off pressure, maybe they can get you the right information on the subject
 
Pop Off Pressure - The pop off pressure is not an adjustment that exists on the carb, but rather a specification that is a combined function of the needle valve size, and the spring rate of the float arm spring. This specification has a wholesale effect on the fuel metering in the 0 - 40% fuel range. Because the pop off pressure has this far reaching range that overlaps with several other metering ranges, we consider it a fundamental starting point.

The term "pop off pressure" refers to the amount of fuel pressure needed to push the float needle valve away from it's sealing seat. Pop off pressure is checked with a hand pump that is fitted with an in line gage. The pump is connected to the fuel input fitting of the carb. The return line fitting is then sealed off with one finger while the pump pressurizes the float chamber. The pressure reached on the gauge when the needle gives way is called the pop off pressure. "Adjusting" the pop off pressure is discussed below. If you don't have a pop off pressure gauge, you should get one that has a gauge and pump capable of 30 psi. (Most Mikuni distributors carry them) At the beginning, it's only important to check that the needle holds the pressure back with no leaking up to the point where it pops cleanly away from the seat. Perform the pop off test several times to confirm the actual pop off pressure. Initial pop off pressures on the Mikuni and Kiehin carbs (unless otherwise specified) should be no less than 25 psi and no greater than 35 psi.


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Basically....Don't worry about it as it's preset in the carbs and non-adjustable.
 
Ducky said:
Pop Off Pressure - The pop off pressure is not an adjustment that exists on the carb, but rather a specification that is a combined function of the needle valve size, and the spring rate of the float arm spring. This specification has a wholesale effect on the fuel metering in the 0 - 40% fuel range. Because the pop off pressure has this far reaching range that overlaps with several other metering ranges, we consider it a fundamental starting point.

The term "pop off pressure" refers to the amount of fuel pressure needed to push the float needle valve away from it's sealing seat. Pop off pressure is checked with a hand pump that is fitted with an in line gage. The pump is connected to the fuel input fitting of the carb. The return line fitting is then sealed off with one finger while the pump pressurizes the float chamber. The pressure reached on the gauge when the needle gives way is called the pop off pressure. "Adjusting" the pop off pressure is discussed below. If you don't have a pop off pressure gauge, you should get one that has a gauge and pump capable of 30 psi. (Most Mikuni distributors carry them) At the beginning, it's only important to check that the needle holds the pressure back with no leaking up to the point where it pops cleanly away from the seat. Perform the pop off test several times to confirm the actual pop off pressure. Initial pop off pressures on the Mikuni and Kiehin carbs (unless otherwise specified) should be no less than 25 psi and no greater than 35 psi.


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Basically....Don't worry about it as it's preset in the carbs and non-adjustable.
Click to expand...



so what you realy mean is the pressure that opens the float needle?

as far as i can se the walbro carbs have a fuel pump that gets pulses from the crankcase, this pump feeds the crab with fuel from the tank.
the float needle is managed by the float membrane on the top og the carburetor.
on one side of the membrane we have atmospheric pressure and on the other side the float needle an spring. the float needle will open when the level of fuel drops and will be pressed open by the membrane when the pressure in the float chamber drops under the atmospheric pressure.

as far as i can understand it wil give no effect whats so ever to play with this setting. to low float level and the engine runs lean at top speed. to high a level end teh engine will act erattic at idle and low speed.
 
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I didn't actually write the info myself, only the last bit which is basically it's not an adjustment worth investigating on our engines. :)
 
Pop off is adjustable simply trim spring to lower psi for nitro/methanol pop at about 12 hold at 6 about a half a lever down with gasket installed
 
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