[Unit 5302]

There's more to it than piston rings. There are valves, valve springs, buildup on the head, bearings, pins, and other items. On a bike, a a ring job and rebuilding the head are required to do a good job.

The stroke of the engine isn't a major concern here. I fail to see how that comes into the equation at all, really. A long stroke engine turns less rpm than a short stroke engine, and a short stroke engine travels shorter distances. For the most part, it all works out in the end. Changing direction with 100% greater frequency puts a hell of a lot more stress on parts like wrist pins, and 100% more useage on the cam, and the valvetrain is also a significant increase.

The valvetrain on the S2000 will see the equivelent of 200,000 miles when compared to a large displacement V-8 at 100,000.

Like I said, there is only so much you can do to make an engine last longer. The S2000's engine will be seeing 2x the amount of wear cycle of a large displacement V-8.