Yes much smoother. THAT CONFIRMS FUELING ISSUES..
Sorry I neglected to check the plug colors but Cylinder 2 was still running hotter .... Single barrel Carb is back in my John Deere now so can't check this now.
Can you please explain why the hot cylinder is the one that's working properly? THAT'S THE SIDE THAT'S APPARENTLY GETTING FUEL AND WORKING. NO FUEL (OR LITTLE-FROM THE CARB OR CRACKED MANIFOLD) MEANS NO FIRE(POWER) FROM THE OTHER CYLINDER (IT'S RUNNING COLDER AS THERE'S NOT FULL POWER BEING DEVELOPED)
Yes I've tried spraying the plastic manifold a few times now... But it's never shown anything.
So we have one vote for Single Carb and one vote for staying with the Dual Carb.
IMO, YOU CAN GET BY WITH THE SINGLE BARREL. KEEPING WITH THE DUAL WILL ALLOW MORE AIR FLOW, MORE EFFICIENCY, MORE POWER
Has anyone swapped out a plastic twin barrel manifold for an aluminum twin barrel manifold?... are any modifications required?
Can't answer that but if you stick with the two barrel carb (properly fixed or replaced) and your plastic manifold is fine, it's probably moot.
IMO, it you can replace the plastic with aluminum, I WOULD change it, much more durable.
Lastly, inspect that plastic manifold with a magnifying glass just to confirm no hair line cracks elsewhere in the manifold. I suspect that one side of the carb(coldish cylinder), is still clogged, running lean (resulting in running rough, "popping"-possibly a "lean sneeze" condition..
**You want to check the plugs with the "old set up" on the engine and not just idling, but full power. You can re-mount the engine in the frame now that the issue is about narrowed down...