Originally Posted by
dan_vector
Quite easily because a lot of the components physically fit. The ISON components are not tuned or matched like the keep on parts are to keep the price of the ISON lower (the parts are the same design apart from the crankshaft). The virtus is a completely different engine of course which I didnt mention.
I don't know about all the whistles and bells of engines but I do know enough to say keep-on and ISON don't share many parts together and I don't think the sleeve from ISON will fit to Keep on although they may look similar. Length is different and inner carvings on crankcase is different. Once I also hoped that I could interchange some parts between engines but it seems that it's rarely possible since they produce engines differently every time though subtle. I haven't dared to try to share parts between two different engines yet, unless the manuals say same part number, so correct me if I'm wrong.