There's a guy over on Pirate4x4.com who has swapped a Yanmar diesel into his motorcycle.

Youtube videos:
Dyno run video
Highway teaser

Pirate4x4 threads:
Dyno thread
Build thread

You will probably have to register with that forum to see any embedded pictures or videos, but there's a lot of neat stuff lurking within, including diesel swaps into other vehicles. Just have to use the search button.