Had to drop the coolent out of the bike for mantanence and now ive done that the water system keeps bulding up with air /pressure any tips or tricks to bleedin the coolant system thanks as i never had problem with it before

When you refilled the reservoir did you squeeze the hoses to purge the system of air. and was it ok before you drained the fluid.

Yea it was fine before i drain it . Yes pumped the pipes to get it through went out and found it was bulding up with pressure so air locked

It is meant to build up pressure when its hot, just top the coolant up again

Have you undone the bleed screw at the top of the radiator?

Yea the filler bottle dont get warm .. left it running for bit and the water in the tank was cold and pipes where warm

It is supposed to be a closed system under pressure. Think of it this way, the greater the difference between the coolant and the ambient air the more efficient the cooling system. Water boils at 100C at one atmosphere of pressure but at higher pressure the boiling temperature is higher than 100C so the cooling system is more efficient. That's why a pinhole leak in a cooling system is a problem. Not because it leaks fluid but because it depressurizes the system causing the coolant to boil. The coolant reservoir is meant only to supply coolant to replace lost fluid when the bike cools down again and the pressure in the cooling system becomes slightly less than atmospheric. This allows the system to replenish its coolant without sucking air into the system.