Maybe someone else will find this useful. It sure worked nicely for me.
I recently discovered a way to modify the tranny of the 2-speed Puch to increase the RPM of the second gear engagement, and also to decrease the difference between the 2nd gear engagement and disengagement RPM.
My 2 speed used to shift into 2nd gear at 17 MPH and shift back into 1st gear when the vehicle speed was reduced to 13 MPH. This can be a nuisance when going up a very steep hill. By the time it shifts down into first gear you have lost too much speed.
By studying the construction and design of the two clutches it appeared that flipping the 2nd gear clutch around (front side to back) might reduce that difference between the upshift and down shift speeds, which is what I wanted. I tried it and it works great. In fact, It now shifts from 1st to 2nd at about 20 MPH (engine is at 6000 RPM) and shifts back down to 1st at 19 MPH (engine is at 3800 RPM). This is using an 18t front and a 35t rear sprocket.