I am about to start sorting the coolant system on my engine. The bike engine thermostat/blow-off cap also has an overflow outlet to go to the expansion tank (which I dont currently have). Am i correct in assuming the expansion tank should then feed back into the radiator? The radiator I have does not have a fitting available to have a small expansion hose attachement. Is there an alternative way to connect the outlet of the exansion tank into the rest of the system?

Alternatively, how about using a sealed expansion tank, such that the air in the tank is compressed as the water enters the tank when hot, then goes back down the pipe back into the system as it cools? Any suggestions? Many thanks people.

[Edited on 2/11/07 by twybrow]

If the hose in the expansion bottle goes to the bottom of the tank it should syphon coolant back into the rad as the coolant cools --- depends on getting good seals on the rad cap and pipe work to the bottle.

However this the way most far eastern car cooling systems are plumbed

Ok, so it could potentially work. I would need to ensure the inlet/outlet to the tank is at the lowest point on the tank and that i have reayy good sealing around that pipe and the point on the filler cap. Sweet - that will make my build a lot easier...