My Ryobi 725r starts, runs for a second or two then stops!

I would inspect carb and see what the difference is between 1/2 choke and no choke. Set the choke, move the throttle and look into carb- doesnt need to be running. Sounds like something is still restricting airflow at no choke.

Zama Carb? Turn both low and high meter screws 2 full turns counterclockwise, and idle speed control to maximum. Prime unit and start motor. Run for about ten seconds and then turn idle jet (clockwise) for maximum rpm and then lower idle rpms - readjust idle meter as necessary along with idle screw. Then gun unit at high speed and turn high screw for maximum rpm. Go from idle to max and make sure there is a smooth transition. If not play a tad with the idle mixture screw till that is achieved.

You may need to change the head for the curved shaft.

where is liaope platyphylla found

check plug and the HT cable the the on / off switch

Typical fuel line routing is:

One line (the one with the fuel filter in the end of it) comes out of the fuel tank and goes to the bottom fitting on the carburator. The second line comes out of the tank and goes to the bottom fitting on the primer bulb. The third section of line goes from the top fitting on primer bulb to top fitting on the carburator. Hope this helped and best wishes.

You can buy new Line to re-spool on your existing head

To get the original parts:
http://www.ereplacementparts.com/ryobi-725r-41bd725a734-handheld-trimmer-parts-c-7931_15633_18592.html

The lower flex shaft should cost around $40, unless you order it online and have to pay shipping. You should be able to get one from your local MTD dealer. (Ryobi is owned by MTD)

do you have the right kmix fuel to addat start on choke let run tell it dies then pump the ball on half choke and chage the plug