What is "base advance" on an Ignitech ignition and how do I set it?

Base advance is the ignition timing when the pickup is at the end of the pulse lobe on the rotor. The unit fires at this point after start and at low rpm (up to the first rpm point of the advance map), which keeps the timing stable at idle. It cannot be changed by software; it is fixed by the physical position of the rotor and pickup on your bike, typically around 10° BTDC (range about 3–22°). You must enter this value in the Ignitech PC software so that the advance map matches the real timing. To determine it: mark the rotor and engine at 25° BTDC, load a map with a flat 25° plateau between 3000–5000 rpm, check with a timing light and adjust the base advance value until the marks align. For multi-lobe pickup systems the software defines a "virtual lobe".