There is a chance that a Gen I to Gen II generator upgrade is just a matter of swapping parts. The only challenge would come from the relocation of the voltage regulator from near the radiator cap to the lower back of the engine area. Wiring from the stator to the new R/R location won't be too bad but the battery wires could be fiddling. It appears that the Crankcase Cover is larger to accommodate the bigger Rotor Assembly. If the size difference is only in length things will be fine, but if the change is in diameter, there may be be faring 'adjustments' required.
The good news is that the crankshaft is the same, Gen I to Gen II so the parts
should simply be plug 'n play. Both the stator and rotor would need to be changed. Additional good news is that the starter gear set that shares space with the generator is the same between the Gen's.
2004
15JW-15411-00-00 COVER, CRANKCASE
25JW-15451-00-00 GASKET, CRANKCASE COVER
5JW-11411-00-00 CRANKSHAFT
5JW-81450-10-00 ROTOR ASSY
5JW-81410-10-00 STATOR ASSY
5JW-81960-00-00 RECTIFIER & REGULATOR ASSY
2008
3P6-15411-00-00 COVER, CRANKCASE $73.28
25JW-15451-11-00 GASKET, CRANKCASE COVER
5JW-11411-00-00 CRANKSHAFT N/C
3P6-81450-00-00 ROTOR ASSY
$310.97
3P6-81410-00-00 STATOR ASSY
$228.81
1D7-81960-00-00 RECTIFIER & REGULATOR ASSY
$159.70
3P6-81975-00-00 PLATE, RECTIFIER FITTING
$12.90
The Gen II parts (less the gasket), with a slight discount would be $785.66; with a 15% discount would be $667.81.
Anyone want to offer a Gen II for comparisons? Anyone want to bankroll me?