Dead bike

[rosso75]

It took a while, with various search words, but I found a few threads indicating that the motors will swap.  Hopefully today I'll have it going.



In the mean time, I've tried various searches for engine numbers and can't figure out what they mean.  Obviously the last 6 match the VIN, but what do the first three indicate?  One engine is stamped 1UX, and the other is 3SK. 

Thanks

[rosso75]

The '90 motor is in the '86 now.  I still have to mount the carbs. 

In the process, I noticed the '90 motor has a 1 wire sensor on the left side of the motor, below the side cover.  The '86 just has a plug.  I checked the wiring diagrams in the manual I have and I could only find 2 sensors with a single wire.  One is the neutral switch, which this clearly isn't, and the other is the oil level sensor, which looks completely different in the picture in the manual.

So what is this sensor?  Do I need it on the '86, and what will I need to do to account for it being missing now on the motor that's in my '90?