Will start only with choke and die out when you take off the choke

need vehicle make and year. "Full" choke will always flood the engine causing it to dye. once running reduce choke. Is this automatic or manual choke?

Check fuel pump delivery for adequate flow. If when choke enrichment is applied and it runs, then dies when choke is off, fuel flow is inadequate and needs choke enrichment to compensate. Also, if engine dies or chokes when increasing rpms, this will be a symptom of too little fuel. Check fuel flow at pump, then, if flow is good, check for carb blockage, unscrew the jet and inspect, check the operation of the solenoid at the bottom of the bowl, it has a wire attached to it. Trace that wire to where it plugs in, unplug it and touch it to the positive pole of the battery, it should retract. If not you need a new solenoid that has the job of metering in gas to the inner bowl below the jet assembly.

check to see if you have spark to engine when it does this...more then likely you have faulty magneto

After you start it and are in the second stage of the choke (half choke ) let it run for awhile until it warms a bit then try openning choke and going to full throttle.

Do you mean that you can start it normally using the choke (that would be choke CLOSED), but then it dies immediately when you move it to run (that would be choke OPEN)? And if you leave the choke in the starting position that it dies after 20-30 seconds?----- If I have that all right, then you definitely have a restriction in the gas supply. Drain all of the gas from the mower and don't use any old gas. If you have any more old gas (from last season) don't use it. If this mower has a gas filter, replace it. Put just a little fresh gas in the tank plus a little of the cleaner. Start it up, do that a few times if needed. Use a fuel additive such as Sea Foam to keep the gas from gumming up so fast.

The machine is doing the right thing by dying. The role of the choke is to block the air intake and allow more gas to go into the carb. It is meant for starting a cold engine. If you apply choke to a running engine, it will flood the carb and cylinder and not allow it to ignite. The spark is enough to ignite a mixture os gas and air and not gas alone. Hence the engine dies. So give choke only when starting under cold/freezing conditions.
There is nothing wrong with your bike.

Most of the small outdoor power equipment that I have used takes the following to start:

1. Prime 6-8 times, or whatever the manual calls for.

2. Choke the carb to full choke.

3. Pull starter rope. It may sputter and die.

4. After it sputters and dies, put the choke on 1/2. Pull a time or 2 more and should start. Run like that 10 seconds or so, then take choke all the way off.

Most of the small outdoor power equipment that I have used takes the following to start:

1. Prime 6-8 times, or whatever the manual calls for.

2. Choke the carb to full choke.

3. Pull starter rope. It may sputter and die.

4. After it sputters and dies, put the choke on 1/2. Pull a time or 2 more and should start. Run like that 10 seconds or so, then take choke all the way off.

Sounds like the carb needs to be rebuilt. Those tiny jets will clog easily and need to be replaced. The diaphragm is also a large part of bogging and dieing. Hope this helps.

If it will start on choke and die when choke is taken off...the carb needs to be taken off and cleaned. The main jet in the carb is probably clogged.