225 was just about as big as they could go and have it live. Plus, the head was designed for 170 ci and was never really changed for the 225. The stock head sucks.
Ah that makes sense. I think the slant 6 and its reliability was a result of its over engineered stout construction but also the fact that it was not powerful adds to longevity. Just like the beloved Honda 4 cycle motorcycle engines on the 1970s. Those single, twins and inline 4 cylinder SL XL and CB engines were not eye watering powerful but because they were low stress lower power they last damn near forever.
