 The Pantah's performance easily surpassed that of the ill-conceived 1976 parallel twins.The 1980 Pantah 500SL had a plain bearing crankshaft and the same bore and stroke as the old 500 racer, 74 mm x 58 mm, but the head had a 60 degree included valve angle.The engines were noticeably lacking in bottom-end and mid-range torque, but theyrevved freely enough.