Hello, after 20 years of abstinence I drive once again a Honda CB50J. I bought the machine used and I would like to restore some functions with this old vehicle (built in 1979) and refine others. Specifically I have the following problem: probably the valves in the cylinder head are not as functional as 25 years ago and the engine doesn’t turn as high as it could (max. 9000 rpm), even if correctly installed I have decided to revise the valve system of my little Honda. Now the questions: are there in the meantime for the Honda CB50J valve sets (valves, valve guide shaft, etc.), which are suitable for lead-free petrol? Can I do without additives for unleaded petrol if I have completely renewed the two valve sets on the CB50 engine? And especially important: is the installation and installation of the valve sets without special tools good or rather bad mö like ? Many greetings and thanks for your answers… Bernd