The short answer for the cylinder is no it is not interchangeable, the newer cylinders have 3 shafts for the KIPS, however, If I needed a cylinder for an older unit and all I could find was a newer one, I'd build the cases up around the area of the 3rd kips shaft machine it flat and drill the hole. I'd use some devcon aluminum putty, it gets real hard and does a good job of bonding. If you knwo somebody that is a good aluminum welder they could probably build it up but it may warp the cases. The clutches are different than the 88 and newer bikes the crank could be used but is different than the newer ones (new ones use a snap ring to hold the crank gear, older ones used a nut. trannies are different, on the left side case yours uses a caged needle bearing, the newer ones use a ball bearing, they are different sizes so you couldn't retrofit with a ball bearing. the clutch actuation are on your motor uses sleeves rather than neddle bearings on the new ones. The ignition is the same from 86-89 90 uses a bigger flywheel and different ignition.
Thats about all I can think of off the top of my head, if there are specific questions fire away and I'll try to answer them.
