Thanks for the hints and tips guys, I appreciate them. Just for the record the cast part is a stationary part of the engine and won´t rotate in any way, so the surface quality and balance is not critical.
This week I decided to make the water tank for the upcoming water injection system, a couple of evenings ago I made a styrofoam mockup to find the right size and shape for the tank. The idea is to make it double as a chest rest so I won´t have to hang all of my mighty 67kg´s on my arms...
With the shape decided I started making the tank tonight in 1mm aluminum.
Not the best looking welds exactly, it would probably have helped if I had bothered to clean the oxide and dust from the aluminum before welding...
Oh well, it ended up leak free and that is all that matters. There is also a AN4 fitting welded to the bottom of the tank.
The result ended up the way I had pictured it, the water tank isn´t in the way for my helmet and with some padding on top I will have a nice rest for my arms while covering up behind the wind screen.
I ordered a water pump, pressure regulator and a high flow spray nozzle on Ebay last weekend so when I get it I can hook everything up and do some flow tests.
Cheers!
/Anders