Crankshaft location and end float.
The Saito crankshaft is a light push fit in the bearings, with the prop driver removed light to moderate hand pressure will push the crank shaft out the rear of the case. After the engine has some running time the crank will tend to lock itself in the bearings, and it becomes a moderate press fit because of the dried oil accumulation between the crank and the inner races of the bearings.
With the front and rear bearings fully seated and the crank pushed all the way forward, there will be a small gap between the thrust face of the crank web and the back of the rear bearing.
When the engine is first run, and gets fully warmed, the dynamic loads from the prop will pull the crank forward, and the hot crank case will allow the front bearing to move forward slightly, pulling the crank against the rear bearing. From this point the rear bearing has assumed all forward thrust loads on the crank, and the fit of the front bearing in the case prevents any apparent end float.
If you have perceptible end float in a Saito crank after it has been run for a while, dismantle the engine and check the fit of the front bearing in the case. If it’s loose the fit can be tightened by plating the outside of the front bearing, but the “Correct” repair is a new crank case.