Burping

It is the same for my new 912ULS, after 20 rotating, no burp… my plane is a Aerotrek A220 with 80 hours since new…

Some additional information will be helpful;

 - Engine hours?

 - Describe, in detail, your "burping" technique?

I can get my, just under 200 hr, 912ULS to burp in under a complete prop rotation.

This is because I burp my engine after the last flight of the day, when oil hot. The hot oil is easily moved/returned to the tank.

I burp again before the first flight of the day 2-4 SLOW compressions.😈

If you have to rotate the prop more than someone else to get a burp it just means you have more oil down in the crankcase to move back to the tank. It will eventually burp. yes some burp after a couple of turns and some take about 20+ turns. If you have no hydra-lock and your oil level is up where it should be on the stick then getting that last little bit of oil into the tank or raising the oil level another 1/4" isn't an issue. If you live in cold country and the engine is cold it can take a little longer to burp.

Every engine is an individual. Some burp in 3 turns, some 8, some 12 some 20+. There are a few factors that do influence this.