Another member and I were discussing different rear wheel configurations and some of the confusing information that is scattered on various threads, so....I'll try to put all of this into one thread.
Paso 750 with Original 16" rear wheel:
1) Rear axle is 20mm in diameter
2) Rear wheel bearings are SKF #63004-2RS1 with measurements of 20x42x16mm.
Paso 750 with early Ducati rim for 17mm axle:
1) Rear axle is 20mm in diameter
2) Rim's original bearings are SKF #62203-2RS1 with measurements of 17x40x16mm
3) The ideal bearing would be 20x40x16, but no such bearing exists through SKF or other manufacturer.
4) The closest available bearing is SKF #63004-2RS with measurements of 20x42x16.
5) The hub will have to be machined from 40mm OD to 42mm OD to accept the new bearing
6) A new spacer with an ID of 20mm will need to be made for the hub of the rim.
Paso 750 with 907 Swingarm and Axle Assembly and Original 16" Wheel:
1) 907 rear axle is 17mm
2) The ideal bearing for the wheels is 17x42x16, but SKF and others do not make a bearing this size.
*To use the original 16" rear wheel with the 17mm 907 rear axle (if a 907 swingarm conversion was performed):
1) it would be required to fabricate a sleeve to go over the axle to increase it's diameter to 20mm, or....
2) the chain adjusters would need to be bored out for a 20mm axle and a new axle of 20mm would have to be used. The 20mm diameter axle may have to be fabricated if an existing one will not work. The OEM Paso axle is too short in length to reuse in this application (750 axle length is 280 mm and the 907 rear axle is 350 mm with a center, non-threaded section of 305 mm), or...
3) A person may be able to make individual bushings for the inner race of each bearing (don't forgot the bearings in the sprocket carrier!!!) and necessary spacers would need to be machined for the wheel hub and any spacers between the wheel and sprocket carrier and external spacers between the wheel and swingarm....also a bushing would need to be machined and pressed into the rear brake caliper bracket.
*NOTE - With any wheel conversion, the alignment of the rear wheel with the front wheel, and also the alignment of the sprockets with a rear wheel conversion, MUST be checked.
*I believe all of the above information to be true and accurate.
