Originally Posted by BarelyAWake
Keeping in mind not all bottom brackets are the same - I used 499502HNR sealed bearings w/snap rings (5/8" ID x 1-3/8" OD, same as the shift kits) & after lightly honing down the threads in the BB they pressed right in. Add a 5/8" keyed shaft, "BMX" freewheel, threaded freewheel adapter, lock collars & 5/8" keyed sprockets of your choice;
pedal driven: http://youtu.be/U10xLqTekOw
engine driven: http://youtu.be/_GTS0xG8BPM
So were did you get the shaft and bearing from looks real good.