Right cylinder cold misfire.

[vladimirmartin23]

Could unsynced carbs (VERY crudely bench synced with sewing needles) be causing a misfire when the engine is cold? The right cylinder heats up really slowly compared to left, and the exhaust reeks of gas, but once it heats up the problem is completely gone, except for a slightly jumpy idle.

 

[XSSmith]

Yeah, sounds like it. Unsynced carbs can definitely cause a cold misfire and uneven heating. Get those carbs synced properly, and my best guess is that you should be good to go!