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Fuel tube size for 95AX and 1.20AX


Old 09-12-2011, 12:12 PM
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Default Fuel tube size for 95AX and 1.20AX

What is the correct fuel tube size for these engines? There are no recommendations on the O.S. or the Tower sites.

The 1.20AX hasn't been installed yet. The 95AX went from being touchy but working to not working. The club's engine guru has spent several hours trying to get it to run reliably. If, and that's a big if, the plane gets off the ground, the engine quits after a few minutes. Usually, everything gets adjusted, and as the throttle is advanced for take-off, the engine dies. All of your previous suggestions have been done, to no avail. The only thing I haven't changed is the size of the fuel tubing. Since life is too short to fuss with a temperamental engine, I'll be looking for something different.

I just hope the 1.20AX works better.

Thank you,
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Old 09-13-2011, 06:43 AM
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Default RE: Fuel tube size for 95AX and 1.20AX

For up to a 1.20-size engine, we just use regular medium tubing. If an engine will run for only a few minutes while flying and then quit, it's going lean. Usually, this is because there's not enough fuel pressure. Your muffler may not be able to pressurize the fuel tank enough to give you good fuel flow. This is quite common with aftermarket exhaust systems. You may also need to check the pressure lines to make sure the tank is actually being pressurized. Running a too-large prop will also cause problems. Make sure the engine is getting well cooled. O.S. recommends using large props for low noise. Lower nitro content will also help because the engine will run cooler.
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