That's quite possable performance, Our mod YFZ on our Dyno 52 hp =about 6.73 HP/ lb. Our 686 60HP= 6.5 HP/lb (we've made 64hp= 6.09 lbs/HP) so I'm betting our 686's would still loose a YFZ on the hills. (No dunes around here)
Don't get me wrong, the YFZ is an awsome ATV, but to run with a well built 686cc with only 40lbs more weight, well that's a tall order.
Put then in the bumps and it's a differnt story.
Dynoray
SRY, i MENT 6.73 LBS/hp ON OUR MOD yfz'S (NOT6.73hp/LBS)