good job on finding the fuel leak.
those tubes on the carbs are there to catch water and other junk in your fuel.
Make sure you clean your jets and all of the orofices of your carbs.
after you put it back together check the spring in your drive and driven clutches. Also check all of your weights and rollers in the driven clutch. A stuck weight or roller will make the motor and like it has a dead spot. Also check all of the exhaust springs and doughnut gaskets. If they are worn out and leaking it can also cause performance and running issues.
Once you have it running then you can adjust the belt deflection and secondary clutch to the width of the actual belt on the sled. they are numbered as to the specifications. But and I say but, they are all a bit different and need to have the clutch adjusted to each on of them. not alot but the do need some adjusting for best performance.