Hello, I bought a CB 400 N and now have the following problem: Motorcycle needs over 8 liters; 1 spark plug slightly a spark plug completely rusted. Motorcycle stutters with small load, e.g. constant drive under 80 km/h. Runs from 100 km/h quite neatly. Performance is ok at the top and when accelerating. If the carburetors have disassembled, everything seems to be fine, except for tiny holes in the membranes of the shut-off valves, otherwise no dirt, spraying is right Choke flaps make up completely and Is there any advice? I’ve been riding a motorcycle for 24 years and every time I buy a Honda it’s fucking greeting fanjod