I think I can sort out the engine reliability issues. Two stroke engines need the correct cooling to make them reliable. This can be seen with the JPX CriCri engines and the head cooling mods done to direct the air in a controlled manner over the cylinder. The bore needs to be kept as round as possible by making sure the cooling is as even as possible on all sides of the head. Water cooled engines have the coolant channels in the head carefully designed (generally) to cool the hottest parts first and keep the head temperature as even as possible to promote roundness. If the cooling ducts/shrouds are properly designed the engine can be run leaner for the same CHT's due to less fuel being wasted in cooling the engine. To me an air cooled two stroke without shrouding is similar to just using spray from a hose to cool water cooled engine. The cylinder ends up very cold on one side and very hot on the other. A good article is here. http://www.x-jets.com/Design_for_optimum_cooling_efficiency.pdf Shannon.