How do you tell the age of a Honda CRF 150?

The easiest way to do this is to check the cc's of the engine. This number is on the side of the crankcase. From 2003 to 2005, this dirt bike was produced with a 156 cc engine. In 2006, the engine design was changed to 149 cc. You could also find out the dry weight of the bike, that is its weight without fuel and oil. The 2003 to 2005 model was 216 pounds dry weight, the 2006-7 model weighs 223 pounds and the 2008 model is 236 pounds.