Honda 2012 TRX420TM Owner's Manual page 216

Vehicle Identification
Serial Numbers
The VIN, engine serial number, and key number may be required when
ordering replacement parts. You may record these numbers in the Quick
Reference section at the rear of this manual.
The VIN ( ) is stamped on the front of the frame. 1
FRONT
(1) VIN
The engine number ( ) is stamped on the upper side of the rear 2
crankcase.
LEFT SIDE
(2) engine number
208 Technical Information
(1)
(2)