Yamaha FZR400 Digital Ignition Control System. The FZR400 electronic ignition that sparks the engine is computer controlled and operated by the digital microprocessor. It has a pre-programmed ignition advance curve. This programmed advance curve closely matches the spark timing to the engine’s ignition requirements. Only one pickup coil is needed to meet the requirements of the digital igniter unit.

The digital igniter also includes the control unit for the electric fuel pump. The FZR400 electronic ignition system consists of: Pickup coil, Wave-shape shaping circuit, Edge detection circuit, Latch circuit, Microprocessor, Free-running counter, Comparison circuit, Register, Flip-flop circuit, Driving circuit, Ignition coil, and Digital igniter unit. The following schematic shows the Yamaha FZR400 Digital Ignition Control System Circuit and Wiring Diagram.

Yamaha FZR400 Digital Ignition Control System Circuit Wiring Diagram

1 Main switch
7 Fuse “MAIN”
8 Battery
9 Fuse “IGNITION”
10 “ENGINE STOP” switch Diode block
13 Sidestand switch
14 Sidestand relay
15 Digital igniter unit
16 Ignition coil (#I and #4 cylinder)
17 Ignition coil (#2 and #3 cylinder)
18 Pickup coil
19 Spark plug
27 Neutral switch

The following operations are digitally-performed by signal from the pickup coil signal:

  1. Determining proper ignition timing.
  2. Sensing the engine revolution speed.
  3. Determining timing for switching on ignition coil (duty control).
  4. Increasing ignition coil primary current for starting the engine.
  5. Sensing engine stall.
  6. Preventing over-revolution of the engine.


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