I dont see a vent hole on it but have tried cracking it open as well. Think I may just need a new carb not having any luck finding a new choke shaft or plate. I'll try and pull that all out and see if I can fix what I have but pretty sure I can't.

i know the throttle butterfly was available from the dealer. as they put one in ours.
try a thin o-ring on the shaft pushed against the body it might help it seal.

the other thing is have you got the throttle and choke butterfly's centred properly. loosen the screws hold em shut then tighten.
a smear of grease over where the shafts go through the body could help too.

sounds like you had a sticking float/float needle or it was vacuum locking the tank and not letting fuel through. get a 1/16th drill and drill a hole in the the domed edge of the cap.

yes a old trick to help a engine that hasnt run for a while is squirt of engine oil down the spark plug hole. ( i have done that myself a few week ago it does work. bloody thing wouldn't fire a shot of oil and away it went they can get stuck rings a little oil helps till the rings warm up and unstick em selves) actually its part of doing a compression test.

new bushes will help. any machine shop can make you some the shafts are simple. the cousin said to us about him line boring ours in the milling machine and fitting new bushings.

the linkage rods could be part of the problem worn ends or slightly bent out of shape would stop em closing proper.

The issue with the choke plate is that there are supposed to be two pins on the mechanism that turns the rod one was missing. I made a little rod to fit it but it only catches sometimes so when it catches it closes properly now but if it misses will only close half way. I reached out to a carb place that is checking if they have that part but do have a new original. No idea what the cost is on the new one yet but might have to go with that if they don't have parts. I'd like to be able to keep the air cleaner on but with the choke issue I have to keep it off so I can see if the plate closed or not. Getting good fuel through now spark is there and after adjusting the float again it was running but still needed hand choked. Luckily my hand was not there when one of the choke plate screws went flying, guess I didn't tighten it back enough.

I searched for any vacuum leak while it was going and couldn't find anything. I was using a stick to plug that exhaust manifold and pulling it didn't make a difference. I'll try adjusting the float again, that's the only thing that has helped. Just odd because it was at the measurement they called for but carb didn't like that. At this point I'm about ready to just buy the new one just to be through with this issue and move on but with my luck I'd get it and find out that's not the issue.

it could be such a fine leak you wouldnt find it. could be a hairline crack some where. could be bad rings. do a compression test.

I'll give that a shot need to buy a tester can't seem to locate my old one. Tools just like to dissappear whenever you need them.

Old hack
Pony gas engine intake leak 🤔 carb leaks can be identified by spraying ether, WD40 or carb cleaner around the carb and around the manifold while the engine is at ideal. If the idle changes there is a leak. Helps locate any leaky areas.

thats worth a try.

Agreed, I'll give it a shot after I have a chance to go to the hardware store and find a replacement screw for the choke plate. Have no idea were it flew off to but pulled the carb and it didn't land in the bowl and bore scoped the exhaust manifold to ensure it didn't end up in there. Seem to have dodged a bullet there luckily. Hopefully there isn't a Crack in the carb that I can't see because the carb shop that had one wants a thousand bucks for it.

$1K for a carburetor?
That is called "incentive", fix what you have!
CTS