Bogging down at 55mph

So I'm riding a 1982 kz440 and I have spent the better part of last year getting it road ready. I took it out on the highway today for the first time and it got up to 55 mph just fine but when I give it more gas to try to get up to 65 or 70 it loses power and stays at 55mph......I've got the fuel/air mixture at 2 turns out, clean carbs, and a new air filter.....any advice? 

Do you have the stock air box?  Stock jetting?  

One good thing to check is the mechanical timing advancer.  These can get stuck.

The bike is completely stock. Im pretty sure the bike has dynamic timing so there is no adjustment there. 

Yes....what he is saying is that the advance mechanism can get gunked up/rusted and fail to advance as the rpms go up

Servicing the advancer is normal maintenance. separate the rotor from the advancer body & clean/lubricate it. 
The 650 manual says to fill the groove w grease. yours might be the same. 
Be sure to operate it by hand to make sure the rotor snaps back.

Another thing to check is the ignition coil. Ride the motorcycle at highway speeds, then stop & feel it. press w your fingers. don't get burned by the valve cover. It should be warm, not hot. mine was getting very hot, so I got the green Dyna 3.0 ohm coils from Z1Enterprises.  This solved a high speed hesitation (KZ650 w stock electronic ignition)

In neutral, does the bike easily rev to red line? If so, advancer is probably working.
Remove the air box cover to give it more air. Now does the bike go over 55?

Do you see black exhaust smoke? A problem with the charging system/battery can do that.  High ignition demands, system cant keep up.

It will get up to high rpms in neutral. I will try taking the air box cover off.....i had major issues trying to get the air fuel mixture right, like I said above everything is stock. I've got the weekend to figure something out. 

No black smoke. It seems like it's not getting enough air or fuel...one of the two

Handle the airbox cap w kid gloves as they have a tendency to break. and hard to find replacements.

I had some issues like that. I had cleaned the carbs really well or so I thought. I pulled them off again and ran a stiff nylon bristle off a broom through all the passages. My air/fuel passage was plugged. Put the carbs back on, put a good fuel filter on and haven't had a problem since. Also, the cleaning of the advancer is a really good idea as well as the Dyna coils.

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I had some issues like that. I had cleaned the carbs really well or so I thought. I pulled them off again and ran a stiff nylon bristle off a broom through all the passages.

I like this! Great idea.