The 160 used a 420 chain, it's the same pitch as the 428 but narrower. IIRC from my project the 420 sprockets are harder to find. The splines on the countershaft are the same as the larger bikes though, so you can use the 428 chain and sprockets from a 250 if you'd like. My (ex) 160, I modified it a little. I sold it years ago since it was useless in modern traffic and my wife wouldn't let me put it on display in the living room.
Many thanks, that is very helpful. Got a new chain, 428 and fitted it, looks like a previous owner had changed the sprockets to suit. Old chain totally worn out.
