low compression... another rabbit hole

A leak test takes the guesswork out of the equation (if you trust the compression readings you have)

As long as the engine fires up and runs, I would put some good hard miles on it.  Come back in a couple thousand miles, double check the valves and compression then.  With the clearances at the minimum, you need to watch close.  Often times, bikes coming out of storage will have poor compression, which improves with usage.

And BTW, the photo of the tensioner posted is the later 750 style.  Some 1980's have the old style 650 tensioner, but my 1981 had the never type.

Updates!
soaked the cylinders in marvel mystery oil overnight, twice. Bought new compression tester. Also built leakdown tester. 

engine cold:
cylinder 1: 130+
cylinder 2: 110
cylinder 3: 120
cylinder 4: 120

leakdown shows it’s all in the rings. 
I confirmed by putting a tiny amount of oil in the cylinders and retesting. And by tiny, I mean not enough to even cover the piston. 
with oil, all 4 are approx 150-160. 

I think this confirms that the rings are the culprit. 
that being said, I’m going to try the “Italian tuneup” in the spring once I get some new tires for it. 

thank you everyone for the guidance!!!

In my experience all the KZs tested low on compression even when relatively new. If it runs good enough, I would just ride. They are not going to be a 100hp engine.

Thinking about it that past couple of days...
If the compression changes, does that mean that the vacuum also changes? as in should i check and re-sync the carbs after all this?
Or is the amount of change insignificant on a single intake stroke, as a compression test is checking "peak" pressure that the cylinder(s) can create?
Am I over thinking this?

Last followup (i hope!)
Got the bike up to temp this weekend. decided to check the compression again before winterizing it.
1: 150
2: 155
3: 150
4: 150

Success! Now to let it sit for months and hope it picks up where it left off in the spring.