I am looking for a 1976-1978 YZ 400 cylinder. From my research, they are ported differently than my IT400. They are ported more for high rpm which is what I am after for my drag bike. I have checked ebay and could go that route, but prefer local or "a friend of a friend."
Any old dirt bike gurus may want to chime in on this and tell me if I am correct: it appears that the pistons are interchangeable. It appears that the heads may be interchangeable.
"Squish" area is a phenomenon particularly important to two stroke combustion chambers. Squish is determined by the head shape. The heads may be different between the YZ (hot moto cross) and the IT (boggy trail bike) versions of Yamaha's 400 two stroke.
I've got the exhaust expansion chamber covered. Its a bitchen ex snowmobile performance pipe. Its all finished now an needing only flat black bbq paint.