so here are the current issues i could use guidence on concerning my '78 columbia (aka sachs westlake):
a - i have recently discovered that the symptoms of my bike at high speed point to a main jet that is too large. i am wondering how one goes about getting a correctly sized main jet and making this adjustment.
b - when the bike is off and i am pushing it, the engine becomes engaged and the bike sounds like it wants to kick over. the back tire takes real effort to spin when the engine is off and ends up rubbing on the ground which may have caused...
c - recently when starting up my bike i found the back tire flat. on inspection i found no obvious puncture marks, only weather cracking. is this something that can be patched, or should i order a new tire?