Air bubbles in carby bowl drain

Fuel runs out fuel hose when disconnected from carby ,
Can leave bike sit for a day with fuel turned on and it still won't idle when started,
Idle screw is fully screwed in.
Pw50

Ok pretty sure air may be drawing past screw when it's undone maybe.

Yeah that's about my next move ,
have swapped between old and new carby twice ,
pulled old carby down and shined led torch through jets and venturies
Blew compressed air through,

New carby is on bike haven't even had the bowl off it , but both carbys act the same.
It's either fuel or a air leak by the sound of it when it dies or fluctuates , but I have all but ran out of things to clean , test or replace.

Pretty convinced it has to be carby,
105 psi compression
Crankcase holds 7 psi for hours,
Exhaust defiantly isn't blocked,
Fuel cock filter is clean and fuel bowl fills,
Beautiful blue spark,
Tried with start switch disabled no difference,
Idle screw fully in,
Reed valve looks great and have tried a new one,
Carby fully pushed onto manifold,

MIXTURE SCREW DOESNT CHANGE ANYTHING UNLESS ITS SCREWED RIGHT IN THEN IT WONT RUN,

have new carby and original both behave them same,,
Old carby I can shine light through jets etc as Well as compressed air,

Bike starts easy since exhaust overhaul
Won't idle
Top end is fluttery and not reving right out
Also surges when throttle held open but steady.

Next step will be clean carby and swap over again.
Any more help would be wonderful thanks.

Paw paw yeah I have them for the mig welder , I dislike poking things in jets to be honest, will hope to clean the original carby tomorrow and try it again.

Been reading a bit on automatic advance and some the symptoms sound like it could be worth looking in that direction next.

Ok here's a update ,

Got the f@#%^*g thing going now 👍think it was a poor wire connection but cleaning the carby again defiantly changed something as Well.
Done both jobs at once so can't give a definant diagnoses.
Cleaned and tightend all wire connectors under the seat yesterday but bike was a dog today so put the original carby on tonight after a good soak and blow out , before I started it I also cleaned and tightend the two single wire connectors behind the front number plate , one of those was cruddy and most likely took water in when I preasure cleaned it before pulling the bike down for the new clutch etc.

Bike was hard to cold start so I new the carby was back to the way it used to be , once it fired up it idled 1st time in 3 weeks. Hooray kazaar.
With the exhaust mod the bike now has no rev limit ,sounds like she will peak and detonate if I let it.
I'm very happy for the suggestions thanks , I was reading up on stator failures when I read a comment about preasure washing and bad wire connections.
The carby side of this just goes to prove a brand new carby and a old carby that has see through jets that pass compressed air both can make the bike run the same. Can't believe the clean out changed the carby.

If the bike runs well tomorrow I may have to change my forum name....

Here's a bit about me,

I have a 1991 XR250 with the 280 Ballards kit that eats standard 400s of that age
I recently got a 2009 husqvarna TE450 that is a good as viagra
My son has the pw50 he is 6 and started on the pw50 when he was 3.5 , never had training wheels or governors on it , he just had natural balance and learned throttle control from 2yrs onwards sitting on my petrol tank.

This pw50 was breaking my heart not being able to solve it's issues and let him ride with his mates, look out now.

As for the bubbles I have put that down to air being drawn in when the drain screw is loosened and looking at the overflow route it could possibly draw air in there when the screw is partially loose, let say if I opened the screw further the fuel flow would have filled hose instead of drawing air in like a dredge nozzle.