Hello.
My brothers building a -84 KX500, he has two top ends, that we thought where the same until we got them together...
The silver one is clearly bigger than the other.
The bore is the same.
The bolt patterns are the same.
The reed bolts are the same, so no -83/-84 difference.
The silver one har a coarse sandcast finish.
It has no markings, same on the head.
The ports are bigger, and is handported, as opposed to cast on the stock one.
Question of course: Can it be a SR?