I'm guessing you don't have an impact wrench, but that
would be my first choice. Interesting, but the specs on
my RDE-17, 25 hp, said flywheel nut torque 60 to 65 lbs.
I believe it was my grandfather that taught me when
trying to remove a nut (usually rusted) to use two
equal weight hammers and hold one hammer against
a flat on one side firmly, the using the other hammer,
smack the flat on the opposite side. It's worked for
me many times, but unless you're good with a hammer,
bad things could happen.
Some quick heat from a torch might also aid in removing
If you can't hold the flywheel with the strap wrench
to use a breaker bar, with a "cheater" extension if necessary,
you might find a way to clamp the flywheel from turning,
or using a piston stop in a spark plug hole.