Old thread but some input from me
RX3 seems to be the only engine with the intake port not being a perfect circle and called “EFI” engine
Others if not all others are a perfect circle.
AJP PR5 runs the EFI flywheel like the old Honley and 200 watt stator
Carb bikes have the same stator different flywheel reflecting the use of a CDI
PR5 and RX3 seem to share the same right side cover yet all others are a bit different in water pump outlet and have a kick starter hole.
Stuff 97% interchangeable and suits each other with a few minor tech differences
No idea if the PR5 ecu map is the same or a little different to the RX3, I’ve spotted new ecu’s having what looks to be newer versions marked on the stickers, loads of bikes use the same ecu but different maps.
Not too complex to interchange or get the PR5 motor and might need swap a couple bits to get it to the right spec but not the RX3 motor due to mainly intake port being different
EFI on PR 5 is a little different in throttle body and manifold but I’m sure sensors and the like would be easy enough to obtain by matching numbers
MAP and TPS are the same, stepper tip might be different and injector would need numbers checking but neither would be to complex to get