It sounds like the idle fuel cicuit is plugged.. If the engine is like new, the fuel mapping should be close enough to at least run for the most part...
The newer carbs have no fuel adjustments... The idle fuel adjustment is a brass jet, that technically needs to be changed out with another to be right, but you can also run them a tiny bit loose to cause an internal fuel leak and supply more low speed fuel...
The idle jet is screwed into the side of the carb, primer bulb side, just above the bowl, towards the front of the carb near the intake.. There's a small plastic cover, half the size of a pencil.. you'll have to pry that out with something. Probably destroy it.. That is no problem as you don't need it....
THEN the jet itself is a long brass screw...... Take it completely out...
I think first thing I would do is pull the idle fuel jet out, and blast everything clean with carb cleaner.. If you go buy a new can of carb cleaner, it should have a red tube you can use for poking into small passages.. Use that tube to put right down inside the hole where you removed the idle jet.. Then just blast the hell out of the inside of the carb... THEN clean out the jet itself... Right down towards the end of the jet, there will be a couple small holes.. like three or four hairs huge.. :doah: If they are clogged you're done for, and you'll need to clean em out.. Carb cleaner and a super small wire works pretty great...
THEN just put it back together and see how it acts... The jet is supposed to be tight.... But if it (works but is too lean) you can leave the jet slightly loose to create a leak, and let the engine get more fuel.... If you tighten the jet up, then it's too lean, you can use your screwdriver to crack it loose.. if you go very very slowly.. You can screw it out super slowly, and it will almost work as an adjustment..
It only works for less than one full turn usually.. AND IF you leave it loose, it will fall completely out.. :facepalm: SO you have to take it out, then booger up the threads, or glue it into place with silicone or something.. So it can't move, and stays just loose, exactly where you want it...
OR you can get the older adjustable carb for like an H50 or HS50 type motor, then convert all the choke and throttle shafts out, so that it will work on your OHV engine..
