I have a DA50 that had been running great, it 1st began to not run well, and over time it got worse. After rebuilding the carburetor by the recomendation of desert aircraft, it will now start and ideal just fine but when I advance the throttle it dies. I have adjust the low and high speed needles back to factory settings and then tried to tweet them to no success. I can get full throttle if I chock it just right. (Choke partly closed)

I am out of ideals, anyone have any suggestions?

Sharpy, make sure you have the metering diaphragm, the one with the four mounting holes in it, against the cover and not the body of the carburetor. Dan.

Did you check the reed valves while the carb was off? Those could be an issue.
Next is if the reed valves are okay, sounds like your needles are way out of whack. Start at about 1 1/2 turns out and go from there; high adjust first, then low, then back to high. Check the transition, if it dies it's too lean, if it does a lot of burbling (some is necessary and acceptable since there's no accelerator pump) it's a bit rich.

It sounds as if you starving for fuel at the upper end of the RPM range, open the HSN up some more until it will take throttle W/O any choke.
Then adjust the bottom as necessary for a smooth transition.
If that doesn't work there is something wrong inside the carb like a dirty screen or miss adjusted fuel metering needle. or even the gaskets on the pump side reversed. Try the easy stuff first(HSN) then if you need to dig into the more complicated parts of the carb.

Thanks for the replies all. Pump diaphragm is on cover side and gasket on carb side. When I rebuilt the carb I made sure I put the new parts in the same location as the old parts. The screen was filthy when I tore it apart and thought with a new screen and blowing out all the holes with carb cleaner I had fixed the problem. But no such luck. I will put your suggestions to the test tomorrow morning.

Hmmm, on the pump side of the carb, the diaphragm should go towards the carb body with the gasket towards the cover plate. Just the opposite placement on the regulator / metering side of the carb where the gasket goes towards the carb body.

If you rebuilt the carb and did it correctly. and it still wont run most likely the ignition is going bad. Been there. Same symptoms and a new ignition was the fix...

When I 1st rebuilt the carb I had glanced at the reed valve, and had thought it looked OK. But after taking the carburetor off again to double check everything I inspected the reeds more closely. Two of them were well seated against the housing with good pressure holding them in place, But, two of them were not fully seated, I could see a sliver of clearance between the valve and the housing. I guess this can explane how I could get a great ideal but could not advance the throttle at all without it Dieing.

The Carburetor is so simple I was sure I had rebuilt it properly, all the way down to checking the settings of the metering valve.

I have ordered replacement from Desert Aircraft.

Thanks to everyone who gave me suggestions.

Please refer to posts 5 and 6 above. Are you sure the pump diaphragm is installed correctly as from your description, it in incorrect. Perhaps you just mis-spoke regarding diaphragm / gasket placement. The pump diaphragm is under the heavy cover retained by the large single screw. The regulator diaphragm in under the cover retained by (4) screws. If pump pressure is low or non-existent, the engine can still run with the choke closed a bit or with needle settings opened farther than normal but it won't run right.

According to the welbro carb parts breakdown I have the diaphragm on the side of the metering valve is called the pump diaphragm and as I said it is next to the cover with the thick gasket next to the carb. The diaphram on the other side where the fuel enters the carb and then passes through the little screen is called the valve diaphragm and it is next to the carb body with the thick gasket next to the cover.

I can see we are saying the same thing but using different terms. Thankyou for making sure I was doing it right.

I spoke with the techs at Desert Aircraft, and they agreed the reed valve could cause the problem, we troubled shot it over the phone and with their guidance we eliminated the ignition battery, and the spark IC as possible problems. They did however say that there could be a very small piece of trash stuck in the high speed circuit and that I needed to be very sure that it is cleaned out.

Sounds good! Just wanted to make sure a small detail wasn't being missed. Sometimes its hard to be clear when communicating on these forums.