81 kz440 LTD Belt Exhaust Blockage?

Hello! First posting here.
I have a 1981 KZ440 LTD Belt I traded an extra guitar for as a summer project after one of our cars died. Ran all last summer but couldn’t push it past 55-60. I have been working on it for the past month… carb rebuild/cleaning, new battery, wiring, some gaskets, headlight, painted exhaust and wrapped. 

When I took the headers off, there was a rattle on the right side. Couldn’t see what was in there and couldn’t get it out. Stuck between where the exhaust muffler is and the H pipe. Each exhaust is welded so I can’t just slip off the ends. 

Just getting the bike up and running again as it warms up. But It’s seems like the right side isn’t firing. Plugs are new and set. Exhaust is cold coming out and I have low power. Rpm’s a little high. Checked for air leaks. Carb mixture screws aren’t responding the way they should and I think I’ve ruled out every other issue with them with the rebuild (triple checked). 

Thinking I just need to bite the bullet and cut the exhaust. Thoughts?

muffler baffle weld has probably failed. probably isn't the cold problem. I would swap the spark plugs to see if the problem follows the #2 spark plug, RH side sitting on the motorcycle. then swap the spark plug wires to see if the problem is the coil. 

While the bike is running spray starting fluid in the intake and note if the right cylinder starts to fire.
What does the right spark plug look like? Smell like?