If you have ever flown RC with glow engines, you know that bubbles in your fuel line means the "klunk" line, or pickup line in the fuel tank is sucking air. Your engine will lean out unpredictably and erratically and many times will seize your motor.
I was at the airport one day in the 90's during the time when several of our RC Club members had bought an airplane or an ultralight. One guy was agonizing because his clear blue fuel lines to his Rotax 582 carburetors were showing bubbles in the line, moving toward the carbs! He asked me an another guy what was wrong and how to fix it. This other guy who was not as diplomatic as I am took scissors and cut all the clear blue tubing off the ultralight and stuck black Neoprene tubing in its place. He told the ultralight owner ..."Now, your bubbles in the lines are fixed for good."
Now let me explain why the very knowledgeable friend made a smart change, and why this thread is titled "Flush the Commode."
Worrying about bubbles in the line on an RC glow airplane is wise. Worrying about an aviation 2-stroke having bubbles in the fuel lines is down right stupid if you have float-type carburetors. Here's why. The Bing 54 carburetors have a reservoir bowl, a float, a needle-and-seat, and a fine screen around the Main Jet pickup tube.
Your bathroom commode is a very accurate scaled-up carburetor. The carburetor is always flushing into the intake. Fuel in the "tank" or float-bowl reservoir doesn't lean your Rotax of bubbles come through the fuel line because the fuel in the float bowl vibrates enough to pop most of them and the ones that don't pop, get eliminated when they pass through the fine screen near the pickup tube. The fuel pump pushes gas to the carbs...just like your water pressure sends water to the commode. The float on a lever closes the needle tightly against the seat as the tank gets full. When the flushing partially empties the tank, the float goes downward and raises the needle from the seat and lets more fuel into the reservoir, just like the commode.
If you see bubbles in your clear fuel lines, end your worries by installing black neoprene tubing.
Bryan
I was at the airport one day in the 90's during the time when several of our RC Club members had bought an airplane or an ultralight. One guy was agonizing because his clear blue fuel lines to his Rotax 582 carburetors were showing bubbles in the line, moving toward the carbs! He asked me an another guy what was wrong and how to fix it. This other guy who was not as diplomatic as I am took scissors and cut all the clear blue tubing off the ultralight and stuck black Neoprene tubing in its place. He told the ultralight owner ..."Now, your bubbles in the lines are fixed for good."
Now let me explain why the very knowledgeable friend made a smart change, and why this thread is titled "Flush the Commode."
Worrying about bubbles in the line on an RC glow airplane is wise. Worrying about an aviation 2-stroke having bubbles in the fuel lines is down right stupid if you have float-type carburetors. Here's why. The Bing 54 carburetors have a reservoir bowl, a float, a needle-and-seat, and a fine screen around the Main Jet pickup tube.
Your bathroom commode is a very accurate scaled-up carburetor. The carburetor is always flushing into the intake. Fuel in the "tank" or float-bowl reservoir doesn't lean your Rotax of bubbles come through the fuel line because the fuel in the float bowl vibrates enough to pop most of them and the ones that don't pop, get eliminated when they pass through the fine screen near the pickup tube. The fuel pump pushes gas to the carbs...just like your water pressure sends water to the commode. The float on a lever closes the needle tightly against the seat as the tank gets full. When the flushing partially empties the tank, the float goes downward and raises the needle from the seat and lets more fuel into the reservoir, just like the commode.
If you see bubbles in your clear fuel lines, end your worries by installing black neoprene tubing.
Bryan
