Yamaha F50A Service Manual page 26

GEN
INFO
General information
Acceleration control
This control is activated when the throttle valve is opened suddenly. If the engine speed increases
more than the specified figures, the control of the ignition timing transfers to the acceleration map.
Thereafter, the control of the ignition timing transfers gradually to the control map before accelera-
tion. If it was under warm-up control, the timing transfers to the warm-up control map, and if it was
under normal control, the timing transfers to the normal control map. The control described above
will be repeated if the engine is accelerated again.
Over-revolution control
This control operates by detecting the engine speed. If the engine speed increases to over 6,200
r/min, the ignition of cylinders #1 and #4 is stopped in order to regulate the speed. If the engine
speed increases further to over 6,300 r/min, the ignition of cylinders #2 and #3 is also stopped. This
control will not be deactivated until the engine speed drops below 6,200 r/min.
Overheating control
This control operates in accordance with the engine temperature, which is detected by the signal
that is input from the thermoswitch. When the microcomputer detects via the thermoswitch signal
that the engine temperature has increased to over 80 °C (176 °F), it outputs a signal to stop the igni-
tion of cylinders #1 and #4, if the engine speed is over 2,000 r/min. At the same time, the microcom-
puter issues a warning by operating the warning lamp and the warning buzzer. When the
overheating control is activated, it will not be deactivated until the engine is stopped or the engine
temperature decreases to under 70 °C (158 °F).
The determination of overheating stops when the engine is stopped. However, until the engine tem-
perature decreases to approximately 70 °C (158 °F) or below, the overheating control will be acti-
vated upon restarting the engine. Upon restarting, if the engine speed is under 2,000 r/min, the
overheating control will not be activated for 75 seconds. However, if the engine is operated at over
2,000 r/min for more than 25 seconds, the overheating control will be activated.
Oil pressure control
The oil pressure control operates in accordance with the signals from the oil pressure switch. The oil
pressure is determined to have dropped if the engine continues to operate at over 2,000 r/min with
2
an oil pressure of under 49 kPa (0.49 kgf/cm , 6.97 psi) for more than one second. When the oil
pressure control is activated, the warning buzzer sounds and the warning lamp illuminates. If the
engine speed is over 2,000 r/min, the control stops the ignition of cylinders #1 and #4 so that the
engine speed will not increase to over 2,000 r/min. Once an oil pressure drop is determined, this
control will not be deactivated even if the oil pressure recuperates, until the engine is stopped.
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