Perhaps a bit more on the geometry here? On one hand, it sounds as though you might be describing a deep socket wrench. Or, if it is a hexagonal cavity a ways back, and larger than a typical Allen wrench, you might be able to find a bolt head to fit, put double nuts on the other end, and wrench on those. Or even a threaded rod coupling, if long enough.

It is a hexagonal cavity much larger than any Allen wrench but the tool must have a large hole in the center so the crankshaft bolt can be tightened while the tool is in place.

Dennis Waller

This description is very clear. Could you find a nut to fit the hex, weld a pipe to it, and reach the inner wrench through the pipe? Or a hexagonal piece of plate in lieu of the nut?

We remove the starter and use a steel pry bar to lock the ring gear which stops the crankshaft from turning!! No special tool are high costs necessary!

Thanks to all who replied. I found what I needed @ Amazon:
Powerbuilt/ AllTrade 648796 Honda Crankcase Pulley Removal Tool

Price: $18.55

Engineering Superman's method is nicely straightforward. If this task must be done frequently, it might be worth building a tool, which would save the steps of removing and reinstalling the starter motor. To refine the earlier tool idea, visualize a "spool" consisting of a pipe of suitable size with hexagonal plates (say 1/2" plate) on each end; the plates have holes sized to fit the pipe. A torch, some touch-up grinding, and weld the plates to the pipe....

Oops, never mind. Dennis's solution intervened as I was writing this!

Why not use hex rod and drill a hole?

An earlier post said that the hex cavity was rather large. I don't know how far recessed, which would affect the length of hole to be drilled.

One inch or less depth of hex should be adequate...

It wasn't the depth of the hex cavity; it was the width (not precisely given, but stated as fairly large--see post 2). My 1/2" plate ends assumed only 1/2" depth, anyway. If this hex cavity is further situated some distance behind the access cover, it may take a few inches of length to reach to both wrenches outside the engine. The OP has found the right tool for $18.95, anyway, so this is a bit moot.

D.W.,

This one?

Honda Crankshaft Holder SP60100

Or this one?

OTC4731

http://www.etoolcart.com/browseproducts/Honda-Crankshaft-Holder-OTC4731.HTML

The website lists the models and engines they are used on.

Jon

for the d.i.y.'er. this tool i'm sure works fine. for the shop, we use a 3/4 impact we got from o'reileys - works great (our baddest ingersol-rand 1/2 impacts @ 190 p.s.i. weren't doing anything but making noise).