I meant to add if you cut a new key you really added a lot of timing.
At about 1 deg per .006 you do the math lol.
You should get a timing light on there and see where you really are.
Also watch your head and exhaust gas temperature.
You may not hear the ping ( I have hearing loss ) but you will see the effects of too much timing as a drop in EG temp and increase in head temp.
There comes a point where the improvement drops off with more timing and you start to drop back.
But you won't appreciate it until you careful plot this out in fuel burn and power output.
A point comes when you are causing pressure spikes that are doing harm to the internal parts even though your real power is higher than you were with retarded timing.
I am going out on limb since we don;t have any tables and test data, but 30 deg advanced is as much as I am comfortable with suggesting as a maximum.
That's a .060 slice off a stock key and you have exceeded that by a lot.
One thing I noticed is you can never be sure where the starting point is.
Some clones are so out of the ball park they start life well under 20 ( for NOX maybe? or just sloppy tolerances I don't know )
Need a timing light.
The ignitions on these engines are very very stable.
Once you have a found TDC and back marked your flywheel ( or pulley what ever you are using its easy to see even with cheap Chinese timing light )
This Clone is set at 25 before TDC and runs just under 10:1 compression on pump gas ( this is a stock GX200 with the flywheel and head off a 160. The 160 flywheel is broached for 25 with the stock key so its a bolt on trick for more timing. It burns 91 premium ).
Now see how easy that pull starts, you should be able to get to 25 and still pull start.
But if you increase compression you will need less timing.
Your looking at the grub screw holding the pulley.
I can not see what engine that is.
But its big block.
I know they share a lot of parts and a stock head from a stable mate may fit that block and it may give you a compression boost.
I know you can use a 390 head on the larger Chinese 420 and 440 motors and get a compression increase of about 10:1.
If I was going to rebuild a generator specific for Gen gas I would look real hard at that option.
10:1 is a magic number it still pull starts, timing requirements are less and stock internal parts still work as long as you do not over speed them