What piston? My khyber is a gas guzler, most of it because of the carburettor. Can you explain me a little so I can guide my mechanic.
P.S: Carburettor is adjusted many times by the mechanic (Carburettor repair kit is never used though) but no good, it emits black smoke and the exshaust has a lot of unburned fuel smell.
Thanks in advance.