Ten Valuable Style Points awarded for creativity and thinking outside the box: A circulating, filtering, cooling, oil system for the final drive.
You could do all that and still suffer a final drive failure.
Not to mention, you are going to add a lot of un-sprung weight to the bike, or add a bunch of flexible hoses and a very complex system. And you will spend a huge amount of time designing and trouble-shooting the system.
Having rebuilt a few final drives, I would submit that there would be a lot less work in just preemptively rebuilding your final drive with a new bearing, say, every 20-30K miles (and that is being ridiculously conservative). Just rebuild it correctly, measure preload, don't stress the bearing pressing it onto the crown wheel, and lube it with any gear oil better than WD-40.
Seriously, cudos for thinking of how to prevent a final drive failure, but remember KISS (Keep It Simple Sam) too.
Originally Posted by fpmlt
I just changed my final drive fluid, and got to thinking about a wild idea. Prior to changing it I did a 25 mile run just to warm it up and to get stuff in suspension prior to the drain. I was surprised at how warm the fluid was after only 25 miles, but that is likely a function of a heavy load on an extremely small amount of fluid. And, I'm a believer in the idea that wear causes wear, so the sooner one replaces contaminated fluid the better, especially if there's a limited quantity to begin with.
So here's my idea/thought. Could a guy design a system that would pull fluid, perhaps by electric pump, from the drain, run it through a cooler and perhaps small filter, then feed it back though the fill plug? The advantage would be: adding fluid to the system, cooling and filtering. Don't know how cumbersome or expensive it would be, or if it's even worth the time it took me to think this one up. Just thought I'd throw it out there.