I would like to know the float level for a dt 125 carb

you may have bad piston rings or the float level in carb is letting fuel to pour into cylinder and it is seeping down do a compression test if compression is good remove carb and clean it and check the float level there are videos on you tube for this good luck

try your reeds they might be fouled they are vary easy to fix just gotta take your carb off to get to them

ajust floot level

There are three things that could be causing the problems you mention.
(1) You could have a bad four hole washer in your fuel petcock that is causing fuel flow issues. Rebuild or replace the petcock.
(2)You could be have issues with a sticking float needle or an incorrect float level (or sunk float). Clean the carburetor , check the needle for wear, check the float level measurement, see if the float sinks or floats in gas.
(3)You could have a bad gas cap (gas cap vent) that does not allow enough air into the tank fast enough when it is full. Replace the gas cap or unplug the vent in the cap.

just make it look lever and straight, nothing should be bent in there, take a different or old junk carb apart and you'll see what i mean, they're all the same.

Check if the spark plug is getting sparks.
Check if the spark plug is wet with fuel after a few cranking.
Hope you have cleaned the carb well ..blowing compressed air to its jets and also checked the float level inthe float chamber.

not sure of the exact height, but if you hold the carb level with fuel hose attached and pushing float up with finger, turn on petcok and slowly lower the float until it is just above horizontal. at this point, gas should start to flow out of the needle & seat.

if float turns off gas too soon, then engine will starve.

if float doesn't turn off gas, then it will flow out of the carb overflow tube.

This may not apply to your bike but a lot of the smaller engine 2strokes can still run but backfire if they have one broken reed valve.