912 running rich?

These temps can be very normal during cooler weather and has nothing to do with the carbs. Many place a piece of aluminum tape over the radiator and or oil cooler.

As far as your stains, check the carbs for any leak. Some staining on the bottom many times is just oil vapors from the oil tank vent tube or exhaust vapors from the pipe.

Roger Lee wrote:

These temps can be very normal during cooler weather and has nothing to do with the carbs. Many place a piece of aluminum tape over the radiator and or oil cooler.

As far as your stains, check the carbs for any leak. Some staining on the bottom many times is just oil vapors from the oil tank vent tube or exhaust vapors from the pipe.

Thanks, Roger. These temps are being observed during warm Florida weather, and with the foil tape on both radiators. Is it still common to see 150-160 in 80 degree weather and with foil tape, with long warm up time? My other 912 with no cowling warms faster and to higher temps in colder conditions in Nevada… 

Instrument error ??

I would think a rich running engine would be first indicated by bad performance and mileage. I wouldn’t use oil temp as the indicator. 

Check the plugs to see if they're black and sooty. Maybe the carbs need be synced.