Hi folks . . I am a pretty good mechanic myself, but I am stumped on this 650. It only has 3500 miles on it, been sitting up for couple years. Pulled tank, drained gas, tank in good shape, no crud or rust; pulled carbs, cleaned, replaced both high and low speed jets, gaskets, etc. Replaced both carb intake pieces that bolt to heads. OK, so now, bike starts right up on choke and once warm will sit and idle all day long. However, it will die instantly if you try to open throttle at all to rev up. Yes, I replaced needle valves/seats. If you keep choke about halfway you can finally get it to rev somewhat. The only thing I have not replaced in the carbs is the throttle plungers/diaphragms with the high speed metering rod. Could this in fact be the culprit? My gut continues to tell me it is a lean fuel mix when trying to open throttle. Any thoughts? I didnĀ“t see any pinholes or damage to the diaphragms, and the metering rods seem to move freely. . Help?