There are several things to remember when removing and refitting a Honda radiator.
The first is the fragility of the unit. Most modern Honda radiators are made from an aluminium centre core capped on both ends with plastic tanks.
The Honda radiator plastic end tanks are also fairly fragile and great care should be taken to not knock the plastic locating pins.
NEVER remove a Honda radiator cap from a Honda radiator expansion tank or Honda radiator whilst the engine coolant is still hot. Great pressure can build up in some Honda radiator systems and the fitter must be sure that the engine and it's cooling system have had sufficent time to cool.
If your replacement Honda radiator is of copper and brass construction be careful not over tighten any threaded fittings such as the hole for the Honda radiator fan switch. The fittings are only soft soldered into the Honda radiator tank and can easily be broken if over tightened.
If your Honda radiator has an inbuilt oil cooler with threaded fittings for the pipes ensure they are not cross threaded when attaching.
Always, always, always replace the anti freeze solution when refilling the Honda radiator. The antifreeze also acts as engine coolant as it has a higher boiling temperature than water. Aways use the manufacturers recommended solution and observe the correct ratio of water to anti freeze.
When you are confident that the Honda radiator is fitted correctly and all pipes are sufficently tightened you will need to run the engine until it gets warm enough for the thermostat to open and circulate the water through the entire system. It is ESSENTIAL to remove any trapped are from the Honda radiator cooling system as air expands greatly and can blow a Honda radiator from the pressure build up.
It is advisable to set the heater temperature control to HOT as this will allow water to circulate through the unit. Do not switch the fan on as this will only slow the process of heating the system.