Here is the scoop on different cylinders/rods/cranks/pistons for the different years for the 250R. You can use any year crank, they all have the same stroke length. You can use the 89 head on the 86 cylinder. You will need a spacer plate ONLY if you use an 87-89 connecting rod and an 86 piston. The 87-89 connecting rod is 5mm longer than the 86, but the wrist pin location for the 86 is 5mm lower on the piston. Anyway, you should be able to run an 86 cylinder with an 89 head with a 87 connecting
rod and a 88 piston.

 

OK, so I could buy a Crank for an 86 TRX with the rod for my 85 motor, and I won't need the spacer plate? Thanks again Brian, you've been very helpful!