RE: Saito FG-20 or 21
I think it is normally best to have the LS needle rich (try a full half turn richer) and then you can tune the HS about 10 clicks leaner to clean up the transition and top end. In my view, the best onground tune method is to point the prop to the sky. If it keeps running without missing a beat, it should not deadstick in the air due to the tuning being out. If it suddenly dies, try a bit richer on the HS. If it runs rough, try a bit leaner on the HS. Only adjust one click at a time if you are close.
Grab a sapre spark plug if you don't have one already. Mucking around with the tuning can get the plug pretty dirty and, when you have it running reliable (but it is still rough), a new plug might help.