72CC Carb issues

[ratdude747]

Been a while, some updates:

-added an external breather with filter. I ran the hose to a hanging hot-rod type breather filter which I hung from a strap attached to the petcock mount.
-put in an open element air filter and the suggested jets
-Still has issues:

-When idling, no matter what I do, it seems like I can't get it to run lean enough with the idle screw, both hot and cold. runs best with it bottomed out. This is with the #85 carb jet and #35 idle jet. Even does it with no filter at all. It's like it's dumping in WAY too much fuel. I tried adjusting the CV needle to no avail.
-sometimes misfires at high RPM or when I give it gas from a lower throttle position. the exhaust pulse noises seem to happen later and it's a lower tone with a drop in power (not a lean pop).
-when cold, idles OK for 45 seconds or so, then bogs down and is unstable (any load or a throttle crack too slow kills it). Once warm everything is better.
-I've been getting 65-60MPG if that means anything, top speed on flat land just over 40MPH

IDK if I just need yet another new carb or what... this one seems a bit odd (the construction was kinda weird compared to the corroded original if nothing else).

Other issues possibly related:

-BAD loud exhaust leak, probably due to the fact that the rubber cylindrical gasket doesn't mesh well with the pipe (large weld bead glob in the gasket area). IDK how I pulled it in the past as the suspension member seems to be in the way of one of the bolts hence why I haven't gotten a flat gasket to replace it with.

-Missing engine cover seal that goes around the head; it snapped when i reinstalled it as a result some of the fan air gets directed out of the gap, not out the air exhause at the bottom of the engine.

Suggestions?