OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Victa Lawn Mower Frames Victa 2 stroke engine, broken cut out plug

If the decompressor isnt closing the bang is from the burning fuel/air mix being burnt as it blows through the decomressor valve, Generally any modern one is a unit that is replaced as a whole. You can test it without the decompressor by putting a old spark plug in place of it and blocking the vacuum line that goes to it.