I recently traded a pick-up load of fire wood for a kind of running 181se, basket case 281 and a sort of running 2100cd. The 181 is way down on compression so i'm going to put on a take-off oem 288 top end. What should compression be? Same carb tune as 288? It came with an oval shaped adapter bolted to the low top air filter carb throat. What was that filter kit called and are filters still available?