From PieMan on T-rat responding to much the same question.
"The 2010 and later models of the America and Speedmaster had the speed limiter. For the America up to VIN 611104 the speed limiter can be disabled, but from VIN 611105 the speed limiter is a permanent "benefit"."
http://www.triumphrat.net/cruisers-america-speedmaster/821234-2012-america-top-speed.html