Wont run up to speed without choke partially on. Where are the carb. adjustments? Does it requir a special tool/

May be plugged carb but often this is high speed and low speed carb adjustment. Requires special tool to fit adjustment screw...i always take the carb off and use dremel to cut these two air mixture screws....cut a slot on the top turning them into a slotted screw, then open each one counterclockwise 1/4 turn when carb is reinstalled. Run it and make adjustments two low and high speed screws till it idles nice and throttles up smooth and quick.

Your main jet in carburetor is fouled and needs to be cleaned out. The choke circuit bypasses it but when you remove the choke the gas is supposed to go into engine via the main. If clogged, the engine will quit for lack of fuel.

Either clean the carb and jet or replace carb. And yes, newer carbs have basically non a adjustable jets which is ridiculous since each engine is unique and has to be properly matched to new carb. Way around this is by either buying the special tool (he-- with them) or using a dremel tool to cut into head of adjuster a slot so that you can use a regular flat blade screw driver to adjust.

There is an adjustment. But need special tool. That may not be the problem though. If you are running ethanol fuel in it it nay have gummed up the inside of carb so it wont adjust. If you try adjusting you may lean it out and burn it up.

Most of the newer equipment have EPA carbs that wont allow serious carb adjustment without special tools. The tools are only supposed to be sold to service shops who will make adjustments and then put limiting caps on the adjustment screws. Anyone found defeating these systems can be fined by the EPA. If you think your carb is running a bit lean just use a little bit of choke and see if the engine picks up a bit. Then you can try mixing in some fuel system cleaner into your next tank of fuel and see if that gets you back on track. It is the cheapest way to go before spending any money on shop service or new equipment.

Be safe and good luck!

Possibilities include:
Carburetor has internal air leakage (requiring choke to create more venturi air velocity and hence vacuum to suck fuel through jets)....if older...gaskets dry out...short of "kitting" carburetor can try tightening all carb assembly fasteners....likewise insure carb mount to cylinder is tight. (more daring diagnosticians have lightly sprayed fuel source to external surfaces to detect air leak...engine speeds up when fuel is sucked through air leak)
Another possibility is that the fuel jet is dirty, making fuel restriction..
For that matter, other air/fuel channels can be partially/completely occluded by particulates of corrosion/dirt/etc that can accumulate in the fuel system...let alone plasticizers leached from fuel tubing by alcohol and/or other solvents in the fuel....not to mention other petroleum distillates the can build up with evaporation of fuel during storage....or even as simple as water condensing..
If has conventional adjustable fuel float in float bowel, can be adjusted so that level is a little higher, allowing easier "suck" of fuel through jet and into venturi air stream..
And of course a partially clogged air filter (or even one that looks clean, but the fibers have been swollen by water or inappropriate cleaning solvents).

Your fuel mixture may just need adjusting or your carbs may need some cleaning the adjustment is a bit painful as it requires a special tool for the carbs if you take it in for a oil change ask em about adjusting the carbs for you - a good shop will have it done in a jiffy

is fuel filter in tank clean?

The fact the choke must be 2/3 applied to obtain a smooth idle indicates not enough fuel is being supplied by the carb at idle speed. Applying the choke richens the air/fuel ratio.

I suggest you revisit the carb idle air/fuel jets, air passages and any adjustments as well as checking for intake air leaks.

Your trimmer is starving for fuel. If it is less than 18 months old, my guess is that it just needs a carburetor adjustment. If it is older than 18 months, it should have the carb cleaned and rebuilt, or replaced. Check with homelite.com for the cost of a replacement carb, sometimes they are less expensive than having the old one repaired. If it just needs an adjustment, find a local repair to do it for you. Homelite requires a special tool to adjust the carb, and won't sell the tool directly to consumers. Some shops will sell the adjustment tool. No special tools are required to replace the carb, just basic tools.
Good luck!

You need to play with the timing adjustment, either on the spark plug, or the gap between the contact and the magneto.
That'll do it ;)
Don't forget to rate, thanks