One area that has not been covered in this debate is " Air Filtration" It has been my experience that poor air filtration has caused more damage to my K engines over the past 8 years than any other factor. Until this season I have used a variety of foam filters, some drawing air from within the bonnet area some drawing through the bonnet. At all times the filters were regularly cleaned and preened with the recomended dust retention oils. Routeenly I would examine the inlet tracks and be alarmed to find a thin coating of abrasive dust had passed through the filter. When stripping the engines down at the end of each season, the bores would be scratched, valve guides would show wear, valves seats would be worn.
Last year I fitted an airbox and a massive K&N cone filter, periodic checks on the inlet tract have shown them to be clean with no accumalation of abrasive dust particles. The engine has remained strong without the usual fall off in performance and oil usage is worryingly low.
Rob