Don't try that - at best it won't work (gear ratio too low). If you do manage to lock the transmission solid, AND the drive belt doesn't slip, it's likely an internal gear will break.
Best option is an impact wrench (electric ones are available for less than £20 - best investment I ever made). DON'T use the 'hit it with a hammer' type.
2nd choice - remove cowling and jam a screwdriver in the starter ring gear. The bolt isn't usually THAT tight.
Having removed the bolt, it may or may not (probably not!) just slide off. You may need a puller.
phil_saunders(a)bigfoot.com
P Saunders, July 2009
