Compression readings can vary on
these small cubic motors depending on the unit.
What type or style of tester are you using?
These don’t have an idle circuit in the carburetor so you
need to lean the mixture out about 1/2 a number to get
them to run really slow.
Also the lift of the poppet valve will effect how they run.
To little and the motor wont speed up. To much and they
run like they are rich but leaning out the mixture doesn’t help.
Should be around 3/32. You can use a drill bit and compare
the movement. If it close its best to look elsewhere.
This can also cause one not to idle well.
https://youtu.be/NnDfmCQeoSo
Something else you should be aware of.
https://www.youtube.com/watch?v=cSZO047tTkk
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.