Swapped the carb on my AlphaSport 50 with a Runtong carb off of Ebay. Now when I start it up, it accelerates hard without me applying any throttle input. It goes about 100 feet then dies. The mixture screw is 2 turns out and the idle is 4 turns out. Any recommendations on mixture / idle adjustment? Or does that sound like a throttle linkage problem?

 

Did you also swap The throttle needle operated by the throttle. I attempted a carb swap once without swapping the needle and it ran wide open.

 

I did swap the needle. The new carb came with the throttle needle and barrel valve/slide. And I'm 99% sure I lined up the cut out on the valve with the throttle stop screw in the carb. I'll have to tear it apart and see if the valve is moving freely and the cable isn't bound.