The method is this.
The birdie on the flywheel side 50
The crank of GAG to the clutch side
Both, fill in welding the holes in the crank pin. And it re-drilling.
First, create a piece for the press in order to fill this hole.
I use a heat-treated (In Japan is referred to as a Maruetchi) rod of chromium-molybdenum steel.
SS400 it is weldability of (ordinary steel) is good.
But I gave priority to it to match the material. Perhaps the crank shaft would also be chromium molybdenum steel.
If you design a pin for the strong press fit, it is advisable to loose the angle of the chamfer.
Chamfer angle will fail to press will be nibbled's normal 45 °.
Clutch side is provided an oil passage.
This is something for supplying engine oil to the connecting rod.
So the piece of the clutch side make a hole in 4φ.
I press fitted with a hydraulic press.
This insufficient contact surface of the connecting rod big end is when you stroke up.
So it will weld.
Cleaning the surface of the place to be welded with a belt sander.
And I was welding, by TIG.
The next step is to make a hole in it.