Sorry to disagree Ken, but on our best drag bikes we use lightened
crankshafts
 and clutch baskets. Inertia is inertia, rotational inertia is the
same. It will
 take you longer to accellerate the heavy flywheel no matter what
else happens.
[snip]
 Bill Jepson

An acquaintance of mine who manages an IRL team said something I found
extremely interesting while showing me some stuff.  I was asking why they
use lighter suspension components on less demanding tracks since the
difference in weight is extremely small and the final car weight will be
exactly the same anyway.  He said they have found that over building
components tends to lower reliability.

Keep in mind, I don't speak for him and I'm not a P. Eng.

Lightened flywheels on two stroke drag outboard engines do help performance
but only in a barely measurable way.  To go from a stock aluminum flywheel
to the lightest flywheel that will hold a ring gear will only make about a
1/10th second difference over a quarter mile.  The flywheels are lightened
to raise their resonant frequency.  Many stock OMC V6 outboards have a
resonance at 6200~6400 RPM and they will shear cranks if propped to top out
at that engine speed unless the flywheel is lightened to raise that
resonance above WOT engine speed.

Lightened pistons and rods can help reliability also but I would tend to
think that roughly anything that reduces vibration, lighter or heavier,
will be beneficial to reliability.

My $0.02,

Tom

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