LtMukiwa

Youll probaly get some better advice on tuning engines than from me. But,

When I had this problem it was the needle valve too rich. Check the low speed needle is set to the factory setting, then lean the high speed needle a bit to see if it will start. 3/4 to 1 turn out.
I live in a hot climate and found the needles required to be leaner than the manual suggested.

Once you get it started adjust the high and low needle to as rich as you can, while still maintaining smooth operation.

Do a search on the OS engine forums as there is a few different theories on running in new engines.

Dont run it too lean.

Cheers