82 xj750 carb questions

So I have had this bike since the beginning of the year got a good deal on it. When I first got it I took the carbs off and cleaned them out they were pretty clean already nothing was really dirty took the jets out and made sure they were clean and made sure all the holes were clean and free. Read thew the church of clean and feel confident that everything is clean. The bike starts and idles great on firts cold start use choke and fires right up. Then after a few can shit choke off and it will idle. The only thing I am haveing an issue with is sometimes if I pin the throttle wide open once it hits like 5-6500 rpm it misses out then clears up does not always happen Almost feels like it's starving for fuel. The bike has stock jetting stock air box and after market 2 into 1 exhaust does the main jet need to be to the next size up and also how is one to tell if the throttle shaft seals are bad everything rubber isn't cracking any where on the bike

 

First you have not taken carbs to church ...if you did this would mean all rubber seals replaced including fuel rail O rings. The shaft seals may look fine ...but are usually hard if they have never been replaced. To replace you have to break the rack a full tear down ...butterfly plates pulled to get to inner seals. I highly recommend you read this a carb may look clean but spray carb cleaner will not get into small intrrnal passages. You need to soak each carb in carb cleaner like Berrymans 1 gallon cleaner for about 1 hr per carb . This is why all rubber seals need replaced. After reassembly you bench synch and reinstall and do a running synch.