I have a 1980 sx850 special. I just picked this one up. I had the exact same bike two years ago color and everything. I loved it. The only major problem I'm having is 2nd gear. When I'm on the throttle in 2nd it bangs/ slips out,, in and out with a big slam/ bang. Doesn't happen when downshifting , slowing down no throttle. .??

Greetings Ed, sound bad!...like an engine strip down!!

Evening Ed " hes right am afraid, sounds like you have worn dogs on second gear, or it may need shimmed,[ take out latteral movement] . as gears engage the dogs are undercut,[ slight bevel] this pulls them tighter together, as power is applied..

if the gear has side movement [ even 5mm is too mutch] it jumps out, and all them jumps [ bangs as you describe] rounds off the dogs,