08-26-2018, 06:05 AM
I'm inclined to agree that some form of contamination led to the excessive carbon build up on top of the pistons. Who knows when it happened. For all you know, this could be something that started with the previous owner.
The only time I've seen anything like this was an old Kaw 750 twin engine I tore down for a friend. He'd had it stored in the garage for years and would start it up occasionally to "keep the top end oiled". This is generally not a good practice, but to make matters worse, the gasoline in the tank was well over 2 years old and had degraded to the point where it smelled like turpentine. On pulling the head, I found a thick layer of carbon deposits on all of the piston tops and scored cylinder walls.
The only time I've seen anything like this was an old Kaw 750 twin engine I tore down for a friend. He'd had it stored in the garage for years and would start it up occasionally to "keep the top end oiled". This is generally not a good practice, but to make matters worse, the gasoline in the tank was well over 2 years old and had degraded to the point where it smelled like turpentine. On pulling the head, I found a thick layer of carbon deposits on all of the piston tops and scored cylinder walls.