- If it has a Unit Constructed Engine it is a 2009 model or newer.
- If it has a five-speed transmission, it is a 2004 model or newer.
- If it has an electric starter, it is a 2002 model or newer.
- If it has four wires coming from the alternator it was made after June, 1999.
- If it has three wires coming from the alternator it was made before June, 1999.
- If it has a yellow horn button it was made after June, 1999.
- If it has a red horn button it was made before June, 1999.
You can also tell the model year of manufacture from the Vehicle Identification Number (VIN). If you're considering buying a motorcycle on eBay you may see the VIN number right there in the ad. The tenth number or letter in the VIN tells you the year of manufacture. Here's how to decode it:
S=1994 (Because the factory started building 1995 bikes late in 1994 some Bullets officially imported into the U.S. did get the 1994 "S" VIN number, according to Graham Scarth, chairman of the Royal Enfield Owners Club UK.)
(Some confusion here; in the U.S. 7 should equal 2007 and 8 equal 2008)
You'll also find the VIN number stamped on a plate inside the right-side toolbox. The plate inside my right-side toolbox (top) helpfully gives the model year of the motorcycle and a quaint warning against modifying it to make it louder.
NOTE: This article deals in a general fashion with Royal Enfield Bullets made in India for the U.S. market. If your Royal Enfield is not one of those, or these tips don't seem to help, there is another article, at this link that may help you.