noun: Derogatory term referring to Yamaha's RX-1 snowmobile, in reference to it's excessive weight of nearly 600lbs. Comparativly, a competative Arctic Cat or Ski Doo snowmobile weighed approximatly 470lbs.
The term has also been used to apply to the Apex and Warrior snowmobile lines, or indeed all Yamaha 4-stroke machines. While the apex weighs approximatly 550lbs, the mass disparity has grown, as Arctic Cat and Ski Doo machines have shed weight just as fast or faster.
Rider1: "You bringing the RX-ton out on the lake?"
Rider2: "naaa, tonner stays home, I'm bringing my F7."