Intake valves? Need diagnosis - video/audio provided

[hotshot38]

2005 GZ250 7500 miles (bought it with 4500 miles)
So, I was driving down the highway to work a couple of days ago...about 70mph for 5 mins, gave it a bit more throttle to get around a car and all of a sudden I lost power. No significant sound, just like it ran out of gas, but without all the sputtering. I was able to glide to the side of the highway and wait for AAA.

Here's the video of the 'clicking' sound it makes when I turn it over.


A video of the moment it broke down:

I used a stethoscope to determine the sound is most prominent near the intake valves. I removed the cover and they are still moving up and down while cranking.

Recent work:
Valve adjustment 500 miles ago. - ran fine, lots more power
Carb Clean 100 miles ago - starts awesome....no more 10 minute choke sessions
Changed air cleaner
Changed oil 50 miles ago (yes, there is oil up near the intake valves when I took the cover off)
Bike ran PERFECT for the last 100 miles since the carb cleaned. Golden pipes and nice color on the spark plug.

Steps taken:
- yes, gas going to float bowl
- yes, spark

Any help appreciated on the cost and complication of doing a valve job or worse.

Thanks,
Sean
- mechanically competent, but not a mechanic, and certainly don't have the tools for an engine rebuild.
(Also, I own a 1988 Goldwing GL1500/6) but the GZ is more fun to drive!