help for d4 pony engine

"Ran 30 seconds and then died" sounds like a plugged carburetor fuel inlet needle or stuck float. I would at least take out the drain plug on the carb bowl and see how much gas flow you are actually getting once the initial gush is over.

If you want to work on the float and needle, it is simpler to remove the top of the bowl by itself than to take off the whole carb. 4 screws and take the fuel line loose and its off. The float should rest on the closed needle with the top surface parallel to the bottom of the cover when you flip the cover over upside down.

To clean the bowl and fuel passages in the bottom of the bowl you can easily remove it with a 7/16 universal socket or even a plain socket on a universal joint. Just two 1/4" bolts through the cast iron carb body that hold it on. Be careful not to loose the bulls-eye gasket and carefully tighten the two bolts when reinstalling the bowl. It is pretty easy to strip the threads in the pot metal bowl. Drilling the soft plugs on the main and compensator passages takes only a few minutes and then you can ream out all the accumulated rust and varnish with a drill bit. This can make a dramatic difference in the performance of the engine especially under the load of turning the main under compression. An engine with these passages plugged is usually temperamental as far as choke and throttle settings, requiring quite a bit of choke at all times and still being prone to choking down. The soft plugs are easily replaced with lead shot or blobs of solder from any kind of soft wire solder. I melted a blob into the hole and then tamped it in tightly with a small punch after it cooled.

Paul, update your "My Profile" up top there on the right, with your location (city and state) - there might be a member close by that can assist.
If it ran great, and the timing has not changed since then, then either your spark is weak (a weak spark can still appear ok when you lay the plug on the head to check it, but when it's under compression in the cylinder, it can disappear), or you're not getting the fuel / air mix to the cylinders.

Thank you all for the info. I am hoping to get some time in the next couple days to look at your recommendations. I am located in Gilroy, CA. If anyone is nearby that could offer some assistance I would be more than happy to compensate you for your time.
I am not much of a mechanic. The tractor was left to me by my uncle. It is actually the first "vehicle" I ever drove so has a lot of sentimental value to me. I use it several times a year doing small jobs for a few people.
Thank you!!

Yes, you definitely have members in the vicinity. Hopefully when they read of your plight, there'll be a rescue mission mounted! : ) At least there'll be a chance to jaw about these machines. You've come to the right spot Paul; there is a wealth of knowledge and experience here, and a great bunch of folks as well!

You must be working two probs, 1)You reversed the plug wires and it went from no action to a 30 sec run. If your mag is like mine the rotor is uni directional. 2) After it stared that is a fuel prob, follow ccjersey directions.

Yep. An engine that will run for 30 seconds does not have timing problem.

Thank you all again!! I was really hoping that CCJersey was not going to be right cus his fix sounds the most complicated! HAHA. Unfortunately, I am not able to have the tractor at my house so someone may have reversed the wires just to mess with me.
Could it in any way be the wire that is attached to the "on, off" switch for the pony? I am wondering if it could have a slight worn or even broken spot.
Of course now we have rain for a couple days so it might be a few days before I can get back to it.
Again, thank you all very much. It's really great to see all the quick responses.