As if to really show up Harley for what they are, Buell builds sportbikes using a Sportster derived engine, making 92whp at 6800rpm. They are in the 11's with a gearing limited top speed of 132mph. You can buy them at Harley dealers.
Harley manages to get 60whp from a similar motor with the same displacement. The big 1200 Sportsters are able to do the 1/4 in the low 13'swith a top speed of about 117. Very similar numbers to a 500 Ninja, which is a 19 year old design.
I guess "tractor" is a bit harsh, but Harley motors go flat much past 4500-5000 rpm. The first time I rode one I thought the main jet was two sizes too small, and I told the owner to take it back to the dealer to get it rejetted.