ok, the pump is in the gear box.a lifan 140 and a yx la de da feeds oil from the crankcase, just under the cylinder.
everything thing else pumps the oil up around the bottom stud/cylinder bolt on the kickstart side.(honda posties, lifan, loncin, ducar etc)
the oil normally is directed straight from this bolt through the plate on the engine head and down through the centre of the cam shaft.
as picture above suggests^^^^^^^ this plate is modified with hose fittings to direct oil from the stud bolt, through the cooler first, and then into the camshaft.
all the modification that is needed is remove existing plate, and replace with one with hose fittings....once again, picture above^^^^^^^^^^^^ this is usually two m6 bolts with 8mm heads, and a long bolt through the camshaft, that has a 10mm head. the kit should come with a new gasket as well.
some kits use banjo bolts(picture above,^^^^ and its using two hex head bolts instead of 8mm heads) some use plain hose clamps... all a matter of how much you spend.... banjos are pricks if you need different length hoses, by the way...
i prefer the head feed set up, as the oil is heated up on its journey through the cylinder, and having the cooler after seems more effective. but wtf would i know
im running both types on my lifan 140
just cus i can....
mounting the cooler itself, on the other hand, requires some fiddling around, making space by moving other parts around, then welding a bracket where needed to bolt the cooler to... where it has good airflow, usually just behind the forks(watch that it isnt so close it restricts steering and that the hoses will reach, plus the mudguard clearance) or be dodgy like me when i first got one and zip tie it to the handlebars
<<<<temporary measure to test effectiveness
then theres a wide variety of actual coolers to choose from. some are useless. some arent. some are heavy, some arent....