i just got an 81 cb650c and am having problems. it runs great until 5000 rpm then just bogs out. feels like a governor but i doubt it because if i put it on the center stand and take the load off i can run all the gears up to 9000rpm. it revs fine in neutral and idles good but hit 5000rpm and it feels like it stalls then catches itself in gear restarts stalls....drop to 4500 and it runs smooth. any suggestions please and thank you