In this video, we show you how to check the piston for damage on a Stihl TS420 disc cutter.

Health & Safety Warning - Please ensure that you have safely prepared the machine and workspace. If you are unsure about any aspect of the task please seek professional advice.

Transcript

Today we're going to show you how you can check your piston on a Stihl TS420 Disc Cutter. First, start to detach the water kit from the machine by unscrewing the holder using a torx spanner. For safe keeping you can screw then screw back in place. Now, using the torx spanner, remove the screw that attaches the belt guard to the machine. Using a 13mm spanner release the tension in the belt by turning it anti-clockwise. Once that's been loosened, remove the recoil by unscrewing the three 13mm bolts which hold the it to the machine. Now that's removed, free the belt completely from the machine and detach the arm. Using a torx spanner unscrew the spark plug cap. Then, loosen the three screws on the shroud. Remove the four screws of the air filter cover to free the air and gauze filter. Now, return to the shroud, and completely remove each screw. Rest the shroud back on top of the machine until it's been detached completely. Then remove the four screws which hold the flywheel cover on by using the torx spanner. Once that's removed, lift the shroud and detach the wires from the machine. Remove the spark plug cap, and unscrew the spark plug from the machine. Using the torx spanner, remove the two screws that hold the cylinder cover in place. Now, screw in the piston stop to lock the crank. Use a 13mm spanner and turn anti-clock wise to free the starter cup. Then detach the 13mm bit and return to completely remove the starter cup. Now, use a 19mm spanner to loosen the clutch by pulling it clockwise. Spin it clockwise by hand to completely remove the clutch. Then, remove the washer and clutch pulley. Now that's removed, turn to the exhaust and remove the four screws which hold it in place using a torx spanner. You will now be able to remove this from the machine, along with the guard which sits behind it. From this position you will be able to see the Cylinder, and the piston inside it. By turning the crank you will be able to see the piston move. If the piston looks dry and scored, then you should replace your piston. That's how you check your piston on a Stihl TS420.

Parts

Parts and tools included in the TS420 disc cutter how-to video.

• Non-Genuine Cylinder & Piston Assembly - 410 200
• Genuine Cylinder & Piston Assembly - 4238 020 1207
• Non-Genuine Recoil Assembly 410 217
• Non-Genuine Exhaust Silencer - 410 607
• Non-Genuine Clutch - 400 219
• Genuine Torx Wrench/Plug Spanner - 4224 890 3400
• Piston Stop Tool - 350 103