| yup, you are correct the barrels bolt straight on - the machining I'm on about is at the back of the cases, they need machining for fit up of spacers/bearings to allow the swing arm to be mounted / pivot, as the 916 motor pivot point is totally different to the 851/888.
Baines do a kit for this and that's where the cases are going to for the swing arm pivot modification.
cheers
Neil | 
Threaded Mode