All bikes will, to some degree or another, "piston rattle" if you have too low an rpm, too heavy a load and try to add throttle in too high a gear. If you try to (for example) go up a hill at 20 mph with it wide open in 5th gear, its gonna rattle. That is a BAD thing to do. It puts excessive loads on internal engine parts. Try selecting a gear that will always keep the rpm above 3500 or so as a starting point if you want to accelerate. If you're cruising down the road, putting along in 5th at 2500 rpm and you want to go to full throttle, downshift to 3rd or possibly 2nd, then twist the throttle. These engines need some rpm. They aint V twin cruisers that top out a 4k rpm. They are just starting to run and breathe at 4k rpm.
Earl
Earl
My bike makes a loud rattling noise when above 3500 RPM. What do you think it is? It's done this for as long as I've owned it. It's clearly audible above my Vance & Hines 4-1.
EDIT: It's actually more of a buzzing sound.