So I could smell coolant after riding my 650 but could detect no leak *anywhere*. I needed a pressure tester and thought about running out and spending a hundred bucks on a decent one. Then I noticed my bicycle pump sitting there and thought what the heck:
I unhooked the hose going to the reservoir and plugged it into my bicycle pump which had a little yellow plastic adapter apparently made just for this exact procedure. Stuck the reservoir hose onto the plastic adapter and pumped about 15 psi into it. Found the leak immediately around the upper radiator hose. I shall be using this little trick more in the future.

I unhooked the hose going to the reservoir and plugged it into my bicycle pump which had a little yellow plastic adapter apparently made just for this exact procedure. Stuck the reservoir hose onto the plastic adapter and pumped about 15 psi into it. Found the leak immediately around the upper radiator hose. I shall be using this little trick more in the future.