1. start the engine make sure its a runing engine( before taking anything apart )

2. take all the plastic housing off (sometimes the backplate of the crankcase is plastic more on that later )

3. take the flywheel to a machine shop or someone with a lathe machine the flywheel fins down the raised surfaces where the magnent is located but no further.

4. locate prop hub by having machinist make you one or buy one from a weedwacker conversion site

5. get a resistor spark plug (usually have an R in the part number ie RD7JY not D7JY)

6. make or build an engine mount

7. remove excess material from the motor to lighten it( the plastic parts would mount to a metal housing on the crankcase) also if you had a plastic housing that was part of the back plate you will need to grind down the housing to get a backplate out of the deal unless you want to make your own backplate with engine stuffing.

8. put all together and put on test stand get a tank that has a rubber stopper made for gas and glow.


addendum:
post picture of engine for tips on lightening