it doesnt do it all the time , but sometimes when I cruising around 45 in 5th the bikewill start to vibrate pretty good and theexhaust seems to become louder. it feels like the engine is coming unglued!and wont accelerate as it does normally. but after i pickup speed some it goes away. i took the bike tothe stealershipto have the primary belt adjusted if that means anything. of course it is worse now!
If you are in 5th great at 45 mph you are defiantly lugging the motor. You should always keep the rpms up to 2,200 to 2,500. Thats why you are geting the viberation.