This Bosch electric water pump, part number 0392023004, is used in place of the mechanical pump.

Advantages of an electric water pump.

• Increased Power and Torque
• Increased cooling capability
• Eliminates Heat Soak
• Better control of engine temperature
• Flexible options for pump control

Some more information can be found here.

• Davies Craig
• Hayabusa Cooling System

A coolant flow diagram from the FZR400 service manual can be downloaded here.
Technical specifications for the water pump can be downloaded here.

	Once the original mechanical pump is removed you are left with a 38mm hole that needs to be plugged.
This bung is made from Delrin and has two grooves to suit 32.0 * 3.0mm o-rings. It is an interference fit of size-for-size.	Then just tap the bung into position with a nylon hammer.
Drawing of water pump bracket. Will be 3D printed in nylon.	Printed and fitted. No problems or clearance issues, so I can order some silicone hoses.
The oil pump has to be taken out from the other side of the engine and have the end of the shaft cut off. It used to drive the mechanical water pump, and it is not a good idea to leave it as an unsupported shaft.