mini 1000 losing water

[oldboyracer64]

hi pal got a mini 1000 it runs at normal temp but after about 20 miles i find i need to topup the water, we have replaced head gasket,thermostat,rad and flushed the system out any ideas the water is coming out of the over flow of the rad we think

[Cooperman]

Change the radiator cap. It sounds as though it's not sealing or it's spring is so weak it is allowing the water to evaporate off.Are you absolutely sure it's not the head gasket.
I know you changed it, but did you check the condition of the head surface when you did it? Maybe it needs a light skim.

[interloper]

Have you checked the water pump? these can leak.

[oldboyracer64]

re water pump thats new as is the rad cap been told that the rad cap is the max 15 psi ?