Here is a cheap way to get some pressure in the system and find your leak
with the engine cold.  Hook a bike pump with a gauge up to your pressure  tank.
I use the hose going to the pressure cap and just put one of those  tube
inflator adaptors to the hose.  Pump up to like 10-15psi and look for  your leak.
Just make sure to not pump it up past 10-15psi and you should  be good to go.
 I have found several leaks with this.
YMMV

Kevin
87 Westy