Helix----to get to valves, merely take seat off, one bolt----valve adjust, easy---had 4 new Helix, liked them----only problem all day riding, BUFFETING!-----built in trunk, nice. 3 US models, one Japan (Fusion) it appeared nicer running that US models. As recall about 175,000-200,000 with them. Worked good in WI cold winter weather---always started.