What should always be verified before operating an engine for the first time after an overhaul?

Verifying magneto timing and spark plug condition is critical before operating an engine for the first time after an overhaul because these factors directly impact engine ignition and overall performance. Proper magneto timing ensures that the spark occurs at the right moment in relation to the piston’s position, which is essential for efficient combustion. If the timing is off, it can lead to poor engine performance, misfires, or even engine damage.

Additionally, checking the spark plug condition is important because clean, functioning spark plugs are necessary for reliable ignition. Worn or damaged plugs can cause misfires, increased fuel consumption, or incomplete combustion, leading to potential engine failure.

While the other aspects are important for overall engine health and operation, ensuring that the ignition system is set up correctly is paramount for the engine's first run, particularly after significant servicing like an overhaul.