Aw geez downunder
You made me go look and sure enough my ASP 108 doesn't have a ring and is an ABC. It doesn't even have an oil grove. I don't know why I didn't remember that, the engine towed around my Goldberg Ultimate for a couple of years and did a good job of it too. I also checked my new as yet unused Magnum XLS91 and it also is an ABC without a ring but has an oil grove. The oil grove is so narrow it makes the engine look like it has a fat dykes ring.

Mick

The instructions for the Magnum 91 say to start at 1/4 throttle and open to a very rich half throttle, just lean enough to allow for running without the ignitor, ala what Justengines suggested. The instructions then say after 1 minute open the throttle slowly to full throttle and begin to lean and then start temp cycling with short fast runs then cool down. My Magnum is not a very tight fit at TDC so I wouldn't be afraid of a 1 minute run at rich half throttle but I still think I would have it wide open right after getting it started.