Ok so trying to figure out what is the coolant flow direction in water cooled Ducati's? Anyone knows which one is out, which one is back in and what is the 3rd connector for? All located around water pump?
Hard to describe, but as I see it, the coolant flows from the pump out the forward-facing pipe on the cover to the thermostat. If the thermostat is closed (cold engine) it is diverted up to the Y connector on the horizontal head and hence to the T-piece. Since it can't return through the radiator because the thermostat is closed it can only return through the cylinder heads and out of the cylinders back to the pump via the pipes from the cylinders to the other 2 connectors at the back of the water pump. When the thermostat is open (engine hot), the route is from the thermostat through the radiator via the bottom hose and out the top, back to the heads, out the cylinders and back to the pump.
This picture is from the workshop manual but I think it shows the flow in the wrong direction because the bottom hose always gets hot first.
Ok I seen now 3 different pictures and it still does not make 100% sense. One form Diavel does but on that diagram pipes are way different. I will need to work on it more. Quick question I have a smaller radiator from CBR250R. It hose connector is 18mm so I would need two adapters one form 27 to 18 and one form 25 to 18mm. Will that be a problem? As in flow restrictions will they create to much pressure and entire system will let go or squeeze water in to engine?
Looking at Diavel diagram bottom hose and rear hose pump the water out, middle one is return form radiator. So assuming we bypassing radiator. It goes out to vertical and horizontal at the same time. It goes via vertical cylinder, then head and comes out to T junction where it goes down to horizontal as there is flow restriction after T. From there in the Y joint it goes via horizontal head, then cylinder and back to Thermostat that directs it to water back connector. Bottom water out connector also goes to Y piece at horizontal head, then via head, cylinder and back to radiator. I am basing that on hoses I have form ST2 that do not connect in the same way your picture shows. It connects like picture below:
I doubt if the smaller diameter will make much difference as the hoses between the cylinders and the water pump and from the thermostat to the T-piece via the horiz head are around that size. The smaller radiator might be more of a problem though.
