Get yourself a 12” section of 1” wooden dowel and use it as a stethoscope to determine where the noise is actually coming from.

That's a very interesting noise.  You are in a difficult situation.

As I recall, you don't do the work on your bike.  You take it to a shop.  If that is the case, what do you hope to accomplish by posting the video?  

IMO, you would be better off finding a really good trustworthy shop and let them figure it out.  Typically, the advice provided on the forum is utilized by the person asking the question.  Putting the forum members in between you and the shop only adds confusion. It erodes trust between you and the shop.

On the other hand, if you were to do the work yourself, then you would always have first-hand knowledge of exactly what has been checked, how it looked, if it was tight or loose, how it was adjusted, etc.  You would also learn a lot, improve your skill set, and accumulate the necessary tools.

If I got your situation wrong, please set me straight.

The noise in your vid seems to be more predominant at the top of the engine, and you say it is on the left side.  My vote is decompression release mechanism.  Loosen up the cable and see if the tapping goes away.

You can see some of the mechanics with the tank in place.
But to see if the cam hits the rocker, you need to pull the tank and front inspection cover then rotate the crank while observing the rocker

och wrote on 07/29/23 at 16:52:55:

If the cam is hitting the rocker… no
If the valves are loose… no
If the cam or rocker are worn… no

Try these tests.  Quick & dirty, no need to disassemble anything.  You can see from my 2nd vid that the release mechanism can make a noise similar to yours.

Free play check

https://www.youtube.com/watch?v=uOJmXTcOiI8


Noise check, engine running

https://www.youtube.com/shorts/6MKigSVNKQ0


It seemed like a good opportunity to learn something so I gave it a whirl.  Got me thinkin that I need to check this when I do my clay checks for piston-to-valve clearance.  Something I didn't consider.  There's always something lurking around the corner.

Good luck.

Thank you so much, I will definitely check that mechanism!

I eliminated the decomp system completely.  In place of the cable to actuate the exhaust valves I used a small 2” Allen head bolt.  It’s an easy push on the bolt with my thumb to open the valves briefly upon hitting the start button.
I’ve had this setup for 5-6 years and have only needed to use the mechanism one time to start the engine when it was on the compression stroke.  Other than that one occasion it spins up and starts fairly easily every time.  Keep in mind that I have the 97mm flat top piston with greater than 10.5:1 CR, due to the larger bore and with my head having been shaved 0.015”.