93 XP 657 Generating Coil Question

[jprozo]

I recently purchased a 93 XP 657 complete except for motor. Worthy project all else in new shape. Purchased a great 657 motor to drop in but have 1 question. The Wiring harness that came with the XP is for a double generating coil ( 5 wire ). The harness with the motor is a single generating coil ( 4 wire ). Only odd wire out is the white one, all other wire colors match up. My question is : Does the Armature plate & coil need to be replace to a double generating coil? Or can I piggy back the white wire onto 1 of the other 4. My theory is that possibly the white wire might be for the Tach, absent on newer models. Everything else already hooked up would hate to have to pull out again at this stage for 1 wire, my bad !!