What are the initial settings for the low and high screws on the carb after bottoming them out.

screw jets in untill they bottom out slightly then--
high jet one full turn out
low jet one and a half turns out
slight adjustments might have to be made once unit is running
hope this helps

I haven't heard of Ryobi using a carb different to most similar machines which use a small diaphragm-type carb which uses suction impulses from the 2-stroke engine crankcase to lift fuel from the fuel tank into the carb. There is generally one screw which is a throttle stop and two screws which are fuel volume screws; one with a greater influence at low speed and idle and one with greater influence at high speed. The low speed screw does have some influence at high speed and the high speed screw does have some influence over low speed fuel mixture.

The basic settings of the screws should not be lost and if stripping and cleaning the carb each screw should before removing be carefully turned in, counting the turns, until it bottoms so after cleaning it can be returned to its former position.

The amount of adjustment from the position the manufacturer set each screw to would typically be in the order of plus or minus one-eighth of a turn and if adjustment of more than about a quarter-turn is needed it could indicate the carb needs a thorough clean.

Making an adjustment of one screw means adjustment of the other is almost inevitable. The basic requirement is for the machine to work under load efficiently at high speed and it is usually desirable the machine will be capable of idling. Obtaining both is rather a balancing act and will need some patience and time making minor adjustments of each screw and in practice some compromises must be made and if hard work at speed has been achieved it usually doesn't pay to try too hard to achieve a smooth idle.

Initial settings are one full turn CCW on both low and high side adjustments.

What product and model etc?

Starting with the question which screw is which: the low speed screw is closest to the engine and that makes the high speed screw farther away. Set the screws 1 turn out and then adjust as needed.

Not knowing the model, you can always look on the body of the carburetor, there should be an "H" for the high speed mixture screw and an "L" for the low speed or idle mixture screw. Both screws should be set initially 1 to 1 1/2 turns out from seat and then the carb. will have to be fine tuned from there. The high speed screw is adjusted when the throttle is in fast position, at 1 1/2 turns out you should have a slightly rich mixture so you may need to slowly turn it in until you hear the saw's rpms start to increase. You want to find a medium point between too rich and too lean. The low speed or idle mixture screw is set the same way just at idle rpm instead of full throttle, find a medium between too rich and too lean. You should be able to throttle form idle to wide open without any "lag" or "stumbling". You can also offset any rpm change at idle with the idle speed screw (not to be confused with the idle mixture screw). Hope this helps.

The high speed mixture screw is initially set at 1 & 1/2 turns out. Then adjust it to give good acceleration and top speed, while not closing the screw more than you need to. The low speed mixture screw is set at 3/4 of a turn out. Adjust that, to give a smooth idle. The 3rd screw, the idle speed screw, is set to give a low idle speed without stalling.

left and right screws are for high and low revs bottom screw is mix or drain card screw

all 2 cycle weedeater type carb diaphram presets / initial settings are 1.5 turns after a gentle close. You will of course have to dial them in after the initial start.. (1 and 2 screw types)

tighten the left screw and right screw all the way.
losen the left screw 1 full turn and the right screw 1.5 turn and that should be the factory setting good day.