I recently purchased a new Briggs&Stratton 25 hp motor to replace a motor that destroyed itself from the inside out. After getting new motor mounted and wired up everything fired up and was looking good. I began cutting grass with no issues for about 15 minutes. The motor bogged down and blew a huge puff of blue oil smoke out of the exhaust. It cleared up and ran for about 15 minutes and did the same thing again. One i puff and cleared up. This is the first brand new motor I have ever messed with and was wondering if the rings may not be seated yet or if I need to look elsewhere.