Why Fuel Injection One of the considerations with engine design is its ignition and fuel systems. These can be a nightmare with holed pistons, detonation, burnt valves and seats etc if it is not right. A distributor ignition system has its ignition advance controlled by bob weights and a spring, which very often have slight differences batch to batch.
Many ultralight engines run with a fixed advance with a pickup on the flywheel.
These are run off sensors and in the case of the Ultratec we measure Throttle Position, Water Temperature, Air Temperature, Crankshaft Position, and Barometric pressure. Rich ratios wash the oil from the bores and carbons up the pistons and rings which in turn increases the servicing requirements and the associated costs. BTDC and on a distributor system it may be set static at 10 deg. and advance at the spring rate. BTDC at 3100 rpm that is what you get 27 deg.