Took the "new" 93 XR650L project bike out for it's first real ride this weekend. It has a late model XR 600 carb; starts, idles, & runs good except for a fairly bad stumble when gassed hard from low rpm. It will accelerate OK if I roll the throttle on. Idles well at low elevation when warm with the pilot screw 1.75 turns out. At 2-3000' elevation it takes the stumble is significantly less. Main jet=155, pilot jet=58. Comments?