Losing maybe .25 litre for 60k ride seems the more stops i have the worse the problem. There is no external leak but the sytem pressurises when you rev the motor,5psi per crack of the throttle, I only tested 4 cracks of the throttle as this was 20 psi.I know that sounds like a head gasket but it doesn't leak back into the cylinder so I think its pulling air past the water pump seal.I recently replaced the water pump seal and found two problems, first the supplied oil seal was the wrong O.D and the two bearings that support the water pump shaft have worn the housing, this has me wondering if theshaft cocks over at high speed and allows air to get past the seal. Might try bypassing the water pump and see what happens.Sorry about the long winded answer but incl' info in case anyone is having similar problems.Testing can wait, riding tomorrow.