RE: Saito FA. 80 ABC Tear Down HELP!!
At Top dead center there are two positions
One is where the piston is at top dead center and both valves closed - this is the one you want
The other is both valves are partially open - one is closing and the other is opening - you don't want this one
To set the piston on correctly - look at the connecting rod big end - one side has a little bevel to the edge of the bearing and the other side is straight.
The side of the connecting rod with the none tapered edge on the bearing has little funny swirl marks on the face of the connecting rod
The tapered side of the bearing in the rod goes towards the crankshaft or the front of the engine
The side of the rod with the little swirlly marks where it was rubbing on the back plate goes towards the back plate