From MXA (
http://www.motocrossactionmag.com/Main/News/MOTOCROSS-ACTIONS-FRIDAY-NEWS-ROUNDUP-ONE-WEEK-BEF-9628.aspx) "ASK THE MXPERTS: IS MY 2012 KTM 250SX TOO LIGHT FOR THE AMA NATIONALS
Dear MXA,
I own a 2012 KTM 250SX and it only weighs 218 pounds. Is it legal in the AMA 450 Nationals?
As far as the weight goes your 2012 KTM 250SX two-stroke is legal because 250cc two-strokes are allowed to be as light as 212 pounds and still be legal in the 450 class. It should be noted that a 450 four-stroke can't be lighter than 220 pounds. So the weight of your 2012 KTM 250SX is not an issue. But, your 2012 KTM 250SX still cannot be raced in an AMA Supercross or motocross Nationals because the only homologated KTM two-stroke on the AMA's 2013 approved bike list is the 2013 KTM 250SX. Thus, your 2012 model is not approved. Even weirder, the only Yamaha YZ250 two-strokes on the approved list are units made between 2008 and 2010 (which means that the identical 2011-2013 YZ250s can not be raced). Only a manufacturer can put a bike on the approved list...which requires submitting a few parts for tech and a check to the AMA for $3000. Most manufacturers skip paying the fee for bikes that have little or no chance of ever showing up. Additionally, no bike more than five years old can be raced?which means that the oldest approved model for 2013 is 2008.
For clarification, the minimum motorcycle weights for the 250 Supercross/motocross classes are: 194 pounds (125 two-stroke) or 212 pounds (250 four-stroke). And, for the 450 Supercross/motocross classes, the weigh limits are 212 pounds (250 two-stroke) or 220 pounds (450 four-stroke)."