RE: Pulse water pump.
Mikuni pumps are made of any metal and will have corrosion as I know.
Best pump concept is Walbro and its clones. IMHO!!
Cheapest clone could be ordered at Hobbyking.
Have one and the only visible difference to the original is the color of the rubber valves (yellow instead of orange).
Hobbyking pumps are sold by MHZ Germany and have been imported to Europe by the customers as well.
No issue known so far.