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It sounds like you have quite a trip planned! A journey of such magnitude deserves significant preventive maintenance. You're no doubt familiar with common motorcycle maintenance items (control cables, brakes, wheel bearings, tires, etc.), but my suggestions for things somewhat unique to these bikes follow.
The standard routine maintenance procedures found in the factory service manual should be performed.
If the engine sounds good with no knocking, doesn't consume oil, and has good compression then I'd avoid doing anything with the motor bottom-end (pistons, rings, crankshaft, etc.) But I would do the triple-bypass (cam chain, stator, mechanical seal) as a preventive measure. Replace the starter clutch springs while the engine is apart. Check the oil pump chain and replace if necessary.
Consider an electric fan conversion, but as a minimum replace the fan. For justification, see
here. I have heard, but cannot personally confirm, that Honda has recently changed the fan to address the cracks that frequently happened even on relatively new ones.
Perform the
main fuse modification.
The driveshaft and its u-joint should be fine. I've never known them to fail.
The rear final drives do fail on occasion, though. Make sure yours does not make any strange sounds, especially a ticking or growling noise. Clean and lube the splines with Honda Moly 60 paste. I keep a known good spare unit in a box at home. In the event of a failure it can be shipped to me.
Disassemble and lubricate the Pro-link suspension.
Take some time to go through the
Wiki. Just about everything that can be expected to fail on these bikes has at some point, and the corrective/preventive measures are described there.
Others will likely pile on once this thread gets going.
I've moved this thread to the General Discussion section.