Thanks to you all for the good advise. Let me give a little more information. My plane is a Kitfox 4. I bought it several years ago. I was the 3rd owner. The original owner bought the kit and engine in '95 and never started work on it. The second owner, who was a very knowledgable and experienced builder, had started construction and had mounted and had ran the engine. I ran the engine several times over the last few years while I was completing the build. I regularly burped it and turned it with the started to circulate the oil but it had been a couple of years since it had been run. Recently, I had my friend, the Rotax trained light sport A&P go over it good before running it. It burped good like always, made good oil pressure by hand turning, compression felt good. It started right up, I warmed to up, we got the carbs sinched and it ran like a fine watch. A few days later I had planned to run it up and set the prop pitch but it never would burp and the oil wouldn't come up it the tank but spin it with the starter and instant oil pressure. Also I didn't think the compression felt the same when I hand turned it. So maybe the rings are sticking? It hasn't been flown yet but it's ready if I can solve this engine issue. Question? If it's sticking rings should I run it some, maybe run it hard enough to set the prop pitch? I plan on looking for any kind of crank case leak making sure than nothing is loose. Also, like Roger said, it does have the oil tank mounted high above the engine. The Kitfox 4 has the engine mounted right next to the firewall so the oil tank is always mounted high. Also Roger, yes my oil filter is the older type. I bought several of the older type Rotax filters before the newer type came out. I understand they had the check valve too. So, thanks for all of you advise. I'll be happy to hear from y'all so if you have any other ideas let me know. I'll let y'all know when I get this mystery solved. Thanks, James Thomas
