#1 rich idle
Posted: Thu Jan 15, 2026 10:59 am
Following a thorough engine and carb rebuild (removing all emission equipment) and sorting out problems (due to defective new parts) the engine is running nicely now with the help of a friend with oscilloscope and gas tester.
We see (a low) 2% CO above 1500 rpm but it is still very rich at idle (7% CO, acrid) with no significant reaction to adjustment of needles.
I checked orientation of choke discs and mounted a transparent hose between the carbs to see if fuel from the choke is shut off (which it is).
I am stuck at the moment and kindly ask for your ideas,
thank you
Mark
We see (a low) 2% CO above 1500 rpm but it is still very rich at idle (7% CO, acrid) with no significant reaction to adjustment of needles.
I checked orientation of choke discs and mounted a transparent hose between the carbs to see if fuel from the choke is shut off (which it is).
I am stuck at the moment and kindly ask for your ideas,
thank you
Mark