Just went trought this AGIAN! I registered in WI last year, took 20 min, on the WWW, had my stickers 3 days later. After being harrased by IL dnr, and ticketed for improper registration, I decided to register it in IL. So this year I gathered all the paperwork and start to search for the engine number, well on my ZR600 its on the clutch side of the crankcase, BEHIND the motor mount. Ended up calling my local dealer and gave them my VIN, and they were able to give me the engine number. Oh yeah and I still do not have my reg number from the IL dnr!!!