As an "owner", offer these. the xs650 (in it's many guises, from TX onward) was (in MHOP) the BEST English twin never built. or, more accurately, a fairly reliable , nearly oil tight vertical twin.... In england, they've achiieved a "cult-like" status w/up to like 900 cc displacements/staggered cranks/cams &what not. Statewide, not so much.. The plus side, is like early VW'S & CB750's there were lots of after-market bits made... If you're aim is to build a "bobber/tracker" (again MHOP) This is the best platform to begin with. Be AWARE, however,the xs in spite of being a "simple" Jap twin, It VIBRATES.....It's HEAVY....And unless you find the secret formula, making real HP is of unobtainium. luck g