If the main metering rod is bent, causing poor engine performance, what should you do?

• A. Replace with a larger rod
• B. Replace the rod with a new one of same size
• C. Repair the rod
• D. Ignore the rod

Answer: (B)

The main idea is that fuel metering relies on a precisely sized rod to set the correct fuel flow. If the metering rod is bent, its effective diameter changes, which throws off how much fuel is metered at different engine speeds. That miscalibration leads to poor performance, rough idle, or fouled plugs because the air-fuel mixture isn’t what the engine design expects.

Replacing with a new rod of the same size restores the original calibration, giving the carburetor the exact fuel metering profile it was designed for. Repairing a bent rod isn’t reliable because even a small bend or hidden fatigue can leave the rod out of spec, and you’d risk another failure soon. Using a larger rod would alter the mixture in the wrong direction and worsen performance, while ignoring the issue guarantees the poor performance remains.