Depends on how old it is. On older models, there is a one-way clutch that is turned by the starter, and is screwed onto the end of the crankshaft in place of a conventional flywheel nut. Usually they sieze up rather than freewheel, but it's possible.
If it's the starter pawl type, a squirt of WD40 may well fix it.
Either way, you will have to remove the cowling to find out which it is.
phil_saunders(a)bigfoot.com
Phil Saunders, June 2012
