VW1302 Super Beetle condition

Cylinder head valve clearance adjustment on VW air-cooled motor AD in 1302 Super Beetle changed my chronic perception on OHV low speed motor and led me to the conclusion that more break-in operation is necessary to exert the originally designed performance of the combustion motor, high rotational driving would be effective to make it possible to obtain smooth and active response including transient property at every speed range. Though OHV design had been invited on this 43 years old motor, precise adjustment in mechanical and electric parts in every portion would play an interesting aspect from now. Motor oil replacement and spark plug's gaps precise adjustment at 0,5mm with thickness gauge would be the next attempts. Though I have passed legal inspection in exhaust gas emission, fee I some richer mixture, idle mixture adjustment by air volume control screw in Solex 34PICT3 carburetor would be done. Exhaust pipe end on the main muffler shows carbon deposition.