Gas leaking from air box and not idling well

I have a 1982 XJ650
I received the bike with a seized engine and so far I have :

honed the cylinders ( pistons were rusted to cylinder walls)
Dipped/cleaned carbs to best of my ability complete re-jet kit with floats and needles
Front and rear brakes
Fuel filter
Oil change and filter
New spark plugs
Gasket seals
New battery
All valve clearance in specs EXCEPT the exhaust clearance on the 4th cylinder is tight

I have not “synced” the carbs or corrected the 1 valve clearance but was eager to hear it run.After that work and playing with the idle adjustment screw, I got her to idle around 12-1500 rpm range for what felt to be 5-10 minutes.turned it off to grab helmet and talk to neighbor and when I came back, it would not start. Found only the #1 cylinder full of gas. Pumped the gas out of the #1 cylinder then it started but the Rpms stayed at 4000+ and would not go down so I turned her off. I then noticed a strong stream of gas pouring out of that drain line connected to air box however the carbs were not leaking gas. The gas stream slowed down when I opened the gas tank. I restarted the bike with tank not completely closed and the rpms would literally start at 2k then rise to 4K then back to 2k repeatedly on its own as if I was pulling the revving the engine myself. Turned her off and I also found that #4 spark plug was black but the others looked normal. Also noticed that when the bike was off and petcock in “on” position, a little gas would still stream into the gas filter. Basically the my whole tank pissed in the driveway.
based off other posts, I feel like it’s a petcock and/or gas cap vent issue so I purchased a new petcock and gas cap but curious to see if there is anything else I should look at

All help I’d appreciated and thanks I’m advance

 

Make sure that one of the float valves isn't sticking open. Give each float bowl a sharp tap with the end of a screwdriver or something.
Gas can come out of one of the air jet orifices and into the air box. JAT.

 

I’ll give that a try,appreciate it

 

@Khakis sounds like you've been busy getting this thing going, good stuff.
The exhaust valve should have been adjusted once you had the top end back together.
Carb adjustments later are dependent on the valves all being in spec.
I don't see mention of a carb wet set. This is a cumbersome step but very important as it not only shows if your fuel levels are within spec but also demonstrates that your float needles are shutting the fuel flow when the bowl is full. If they leak you'll avoid the gas/oil mess you've just encountered. Don't mount the carbs until the fuel level is verified and the floats are shutting off.
Agree you'll need to rebuild the petcock as it shouldn't be passing fuel in the on position without the motor running.
Aside from the leaking gas, your unstable running conditions are common until the mixture screws are set and the running synchronization of all 4 cylinders is complete. You have extra fuel everywhere so until that is corrected the carbs can't be adjusted to any accuracy.

 

Setting the fuel levels

You say that you rejected the carbs.

1. Why?

2. What brand of jet kit did you use?

3. When you dipped the carbs what did you dip them in? Did you tear them down to the bare bodies (all rubber parts removed)?

 

ok I’ll look into the wet set and getting that replacement valve shim.appreciate the tips

 

i did the rejet b/c the original owner told me that was the only thing necessary to run but he “ forgot” to mention the engine was seized. I took his word instead or checking for myself at the time and I had no motorcycle knowledge.I used 2 separate jet kits that both came from across the pond. 1 first kit did not come with floats so when I ordered a new set with floats it came from a company called “damineding”. I wasn’t aware of the “ wet set” procedure at that time. I pulled them off rack and dipped them in “berryman chem dip” with them completely bare bone

 

Did you reuse the original throttle shaft seals, or install new?
Did you reuse the float needles and seats, or install new?
The brand of kit you bought is not one that I've used, or heard anything about. There are very few kits for Hitachi carbs on the market that actually work correctly.

This last question is not likely an issue for you at this time, but were you sure to put the air jets back in the same positions, or did you use the photo from a service manual as a guide? All of the service manuals show the air jets in the wrong locations.

 

i believe I re-used original throttle shaft seals b/c those did not come in the kit off eBay.only included jets, needles, gasket and floats etc. and I did replace the needle and seat. I’m open to purchasing whatever carb/jet kit the majority recommends since I’ll be taking them off to go through the “wet set” process..
i used the manual as a guide but when replacing jets, I just took a picture of where the original ones were then referred back to the picture when installing new ones.feel like I did put the air jets in correct place but it’s possible the person before me had them in wrong spot.

appreciate the help

 

Air jets go like this:


Contact info@xj4ever for good ccarb kits and new throttle shaft seals if your wet-set and a bench synch (followed by a running synch) doesn't fix the problem.

 

I would never, unless my spyglass gave me good reason to, change any genuine hitachi jets for some off ebay. I would clean, inspect and refit. The consistency is just not there. That's the reason k-moe is asking where you got them.
@Simmy s advice re wet set is correct. Unless they hold the correct level in the tube when you set them they (or the one that doesn't hold), will flood. Again, aftermarket stuff is not consistent.
Lastly, you need to bench set the butterflies - using the first progression hole edge as a guide with the edge of each butterfly - this is close enough to ride usually.
Lastly again - did you make sure the passages between the idle jets and the progression and idle screw holes were clear?
Ie squirt fuel or carb spray through them?