How to Split Two-Stroke Casings

Splitting engine cases on a two-stroke engine, as found on a vintage Vespa scooter or a lawnmower, can be a bit frustrating and almost impossible if not performed correctly. With a few correct tools and understanding how the engine is assembled, a home mechanic can disassemble an engine properly to open it up. This task usually requires a few specialized tools. You need to remove the clutch and flywheel. Once open, the casings can be separated and the internals removed.

Instructions

1

Remove the engine from the vehicle and place it on a workbench where you can disassemble it. Use screwdrivers to loosen the bolts retaining all the engine covers. Place all the bolts and covers in a plastic tub so they don't get lost. Turn the engine so that the flywheel side faces you. Attach the flywheel holder tool so the flywheel doesn't spin. Use the flywheel puller to remove the flywheel.

2

Turn the engine around. Use a socket wrench to remove the bolts on the clutch cover. Perform the same holding and pulling process on the clutch side with the clutch holder and puller tools. Remove the clutch. Use a screwdriver to remove the ignition coil and wiring as well. Use the socket wrench to remove the cylinder spark plug. Loosen the cylinder bolts as well with the same tool. Pull the cylinder off the engine when the nuts are removed.

3

Use a socket wrench and sockets to loosen all of the engine casing bolts. Confirm all of the bolt nuts are removed before doing anything else. Use crescent wrenches for those bolts where a socket doesn't work. Turn the engine so that the engine split faces you. Begin to tap one side of the engine with a rubber mallet with some effort (don't smack it super hard). Wiggle the engine half as it begins to come loose.

4

Turn the kickstart pedal, if one is present, as the engine half begins to come loose. Continue tapping the half with a rubber mallet until it is completely free. Catch any small loose engine parts that may fall out. Strip off the only engine casing gasket pieces. Begin removing the internal parts as necessary.