Husky 224L is new, starts easy but when i start throttling, the string trimmer barely spins.

Question edited for clarity.
Question moved from MISC to make model category.

Check the video

https://www.google.com/search?q=224l+husqvarna+remove+head

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Disconnect the two halves of the shaft. It should be pretty easy. Inspect the drive cable to make sure it hasnt snapped. Also make sure the cable is inserted into the female half. Its a square shaped cable that spins and drives the string trimmer head.

You use no oil,use regular unleaded gas only,on 4-Cycle engine use gas,2-Cycle engines use the oil- gas mixture,your's is better cause you just need gas.I use Husq's too.

clean carb

Breakdown diagram for 224L

To remove the head to restring, push in the bumper cap/side tabs on the strimmer head, the top should then just pull off exposing the inner spool.

Sounds like a fuel starvation problem, Check fuel lines, filter and primer bulb, also carb may need cleaning or new diaphrams

Have you put the gear head on correctly.? Are the ends of the shafts pushed in far enough?

The throttle cables aren't adjustable. Make sure the other end is on the trigger correctly and that it is routed through the handle and the engine cover correctly. Also, make sure the throttle shaft and throttle plate (inside carb) are free and easy in their movement with the throttle cable off. The engine idle speed adjusting screw may be in too far also. Back it all the way out and then back in with the throttle closed Once the speed screw touches the throttle lever (what you hook cable into) on the shaft, give it about 2 turns in. This is about all you can do. If the cable is stretched badly (rare), it would need to be replaced.

flooding out...change the air filter...