Hot engine after mods

[AaronA1]

So I finally got my bike running, all four cylinders doing what they are supposed to do, everything working great BUT, it's running pretty hot, and all signs point to a lean mixture. Upgrades are pod filters, and a 4 - 1 exhaust. I do believe it's a Mac, 4 into 1. I have the stock 110 main jets, and I'm assuming the stock idle jet. I have no idea what size jet to go to. I adjusted the air fuel mixture screw to give it the maximum amount of fuel that the jets would allow, but after a spark plug reading, all signs still point to a lean mixture. It runs with the choke on, but immediately once the choke is off, the bike dies.
Any ideas on what I can do to make the bike run strong with no choke? And also, any idea what size jets to buy?

 

[AaronA1]

Also, I can feel the slightest bit if air coming from the headers where the connect to the motor. Could that be problematic? It's just barely enough to feel some air slipping through.