1977 YZ 400D. this was the first year for the plastic tank, and DeCarbon Monoshock. It was the king of the open class and a fun bike to ride. This bike had not been ridden in over 24 years when I found it in a barn. It was a plie of junk with a mice living in the airbox. The crank was rusted to the connecting rod and the cylinder was all rust. It took two years to complete.