If you were to look at the side of just about any engine the number on the side does not match the number that is posted by the maker, for example: 250R is 246, DS650 is 653 I think, and King Quad was in the low 200's and they said that it was a 250cc. Yamaha made the engine under 440cc so that is could be raced in AMA MX events and not have to be de-stroked as is being done with the Honda and Yamaha M/C engines.

 

Manufacturer numbers are near meaningless. I've given up trying to explain why my '02 Arctic Cat 400 (371cc) has a smaller engine than my brother's '02 Arctic Cat 375 (376cc). It's especially difficult with the cats because, except for the stickers, they LOOK identical!

 

The old limit was 440cc but they changed it to 450cc. Yamaha was too far into production to bump up the motor.

 

This is quoted from atvsport:

Why did Yamaha opt for 439cc instead of 449, like the motorcycle? Because 439cc falls within the current 440cc limit for the All-Terrain Vehicle Association’s Pro class. When the Pro Production class, with a limit of 450cc, was finalized last October it was too late for Yamaha to redesign the motor.

 

Man the dealer said the exact same thing you said bansheesand, you know the sh#@ your talkin about.