1981 xj650 need help ASAP! Colorado!!!!

My 1981 Yamaha xj650 maxim bought for 100$ wouldn’t start said it’s was the starter, I replaced the battery starter solenoid starter motor new spark plugs new fuel lines new petcock. New fuses did an oil change and new oil filter everything I can think of, was having a high rpm problem was a throttle cable that was pinched, rode it for the first time 10 miles yesterday no leaks just fine, got home put cardboard under it to leak search incase watched for 10 minutes all good then went inside came back out fuel was coming out of the line on the underside of the air box, I need help I’m completely lost and don’t know anything about bikes it’s all been YouTube and manuals. I did have the endings turned to off but the petcock was on prime? Did it just overflow the carbs? Is something wrong? Carbs brand new and cleaned with rebuild kits so new pilot jets and everything else etc

 

Could be the prime position. When you choose prime, it feeds fuel directly to the carbs, non-stop and like you suggested they might be overflowing because you had stopped operating the machine. They will overflow out of the pipe at the back of the carbs, into the airbox.
Try turning back to the 'ON' position, (in this position the machine will only start requesting fuel with the engine running) start the machine and let it idle, whilst revving every now and then.
Also, whilst it is running, try lightly tapping the float bowls of each carburettor with a light (rubber if poss.) hammer and race, because one of your sliders might be sticking inside one of the carbs, causing the overflow into the airbox.

Hope this helps.

 

because one of your sliders......or the floatbowl!..... might be sticking

 

Bad float valve or too high a float level.

 

Seems like the issue stopped anytime I turn the bike on I keep it on fuel instead of prime and nothings leaking yet, although this morning pretty cold I was hearing subtle low backfiring through the exhaust, was wondering if maybe I should clean the exhaust out? Or what do U think?

 

So if you park the bike and leave fuel tap on or res it won’t happen? The prime is for when you have no fuel in tank and you want to fill the carbs. After that “on” or “res” any other time is the norm as vacuum tap opens when bike runs.

 

Yep I leave it on fuel never had the problem again

 

Haha I think I saw your post on Facebook marketplace to sell it?