On Friday, May 15, 2020 at 8:34:29 AM UTC-7, john firth wrote:
Amongst all the weighty deliberations on improving safety,
maybe someone experienced and knowlegable about diaphrgam carburetors
could give me guidance.
I fly a PIK 20E , Rotax 501 unreliable engine which has been behaving erratically, surging but not misfiring that I can detect.

From the plugs I see rear cyl lean, front cyl a bit rich.
Does a split carb diaphragm enrich or lean the mixture?

thanks

John F

I am surprised that it runs at all - the diaphragm is critical for regulating fuel flow thru the carb:
https://www.youtube.com/watch?v=jWBre4-tHsg
You need to overhaul the carb which includes replacing the diaphragm.

Tom