NotTaR of small Gasoline Engines and Rotary Lawn Mowers : Flywheel removal                        
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Flywheel removal

Remove the shroud (blower cover) if you have not done so already. This is usually fastened with 4 screws and hopefully does not involve any head bolts - if so, you will need to tighten them to the proper torque using a torque wrench once you have remedied the problem. You may need to remove the fuel tank (if you have not done this already) and other trim pieces as well.

You should now see the top of the flywheel. In most cases, a large nut fastens the flywheel to the crankshaft. (However, in some designs, part of the starter mechanism is actually used and this is supposed to require a special wrench to remove. However, using a piece of wood as a buffer and tapping the ears in a counterclockwise direction will work also. Refer to your engine manual for details.) Use the proper socket to loosen this nut (counterclockwise). It may be necessary to brace the flywheel securely to gain enough leverage. Make sure this is done against something that can stand the force. Once loose, remove it by hand and then remove any washers or other parts that are under it. Make a note of how these were positioned including which side is up on some cupped washers.

You should now see the keyway. The slots on the crankshaft and flywheel should be aligned. There are two common types of keys:

You may even find that the flywheel is relatively loose on the crankshaft if rotating the blade while holding the flywheel stationary is possible. Either the blade key or the flywheel key or both are broken in this case.

You will have to remove the flywheel to replace the key if it is broken or damaged.

If the flywheel is loose at this point, then the following will not be needed as it can be lifted off.

There are several approaches to flywheel removal:

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