AISEN Tune Up Kit for BR350 BR430 BR450 BR450C-EF SR430 SR450 Blower Air Filter. } The fire danger is so high. There are several things you can check. After arrestor removal, the saw may sound like it is running faster. Spark arrestors are typically built into the exhaust system, in the form of screens or other materials designed to catch and contain any emitted sparks. Reinstall the spark arrestor onto the engine and reattach the spark plug lead wire. 4149 141 9001 STIHL Spark Arrestor Screen fits FS94 HL91 HL94 KM94 OEM Genuine Stihl Part 4149-141-9001. Have you cleaned that screen with a wire brush and or soaked it in carb cleaner and then brushed it ? I think my 4mix Stihl has one though. Abastecedora Parque y Jardin - StihlMaster.mx. You can find them on local hardware store. Id say if your saw is tuned right and you use synth. Yes, spark arrestors need regular cleaning to maintain their effectiveness. I posted this ? //-->,