Norm,
I have an 80hp 912. I did install a primer and use it for all "first starts" of the day regardless of temps. I prime 5 or 6 pumps, do not use the enricher, pull the throttle out about 1/4", switch mags on and turn the key. It starts every time. Our temps range between 100 F and -20F but I don't fly below about 25F. I do not have an engine heater. My plane is always hangared.