New here,appreciate all reply's,first,dont know anything much about 2 cycles.bought an old beach cruiser with the old school rear brake that had a new 2 cycle .ran great,for about 2 months and lately cant fiqure why back tire is locked.can pedal with all my might ,literally ,but then wont turn over also without pedaling bike will just skid.the chain is extremely loose and while i have adjusted it a few times only once was i able to ,get it like i thought it should be .also tried adjusting the clutch,neither has helped ,and as i side note remember i said it had the old school brake so was wondering if that was any factor ,also would like to know ,when the loose chain has ,buckled on the front gear i see that theres a small pin that ..engage ..the motor that a bar with a flat side pushes in.mine come right out,is is suppose to be that free? STUCK and i love that thing,appreciate any reply's