OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S 550ex won't rev up

Hi Speedy, Try running the mower without the air filter and observe any difference. Sounds doesn't make sense but happens to me that air filter slows down the rev. I rebuild the carby with no luck. I removed or replaced with a new air filter and it works fine.