I e-mailed Neil and was told that they are not presently selling nor thinking about selling a 4 stroke diesel. He was kind enough to let me know that it would be difficult for a lay person to do the conversion. The engine needs to be long stroke which would need a new head and cams. Lou Furco ells the gadjet to convert a 4 troke to diesel but you need to use a special fuel which may or may not contain kerosene. What's the energy content of such fuel is unknown to me. I may try it just for the heck of it.