Tecnically, its not an ARCO at all, Its a Model 430 that was made by K.E.Z. enterprises, they were sold like that through the early to late 1980's. This is from a 1988 Kart world catalog:
This one is direct from KEZ, right around 1984
This one is direct from KEZ, right around 1984
Judging buy what KEZ sold, They probably weren't doing much for production of them, it mostly may be just leftover stock dressed up a bit. The ARCO company name was done around 1978 and the company changed to Dialex, added an actual moped to the lineup that was also called an EZ rider which was listed as only being sold roughly 1978-80, Tecumseh was still making specific mini bike engines for Dailex into 1981 in the Tecumseh books I have though. between 1981-84 though is still a blank in the history of them as far as info found online as to when KEZ came into play.
From what I have seen the KEZ branded id decals were placed on the headtube so you may find something there, I would be interested if its there to see if it says KEZ or Dailex only because the one thing you may have spotted on yours that varies from the 2 catalog photos is your does not have folding pegs, which may make it earlier....or even later. From what I have seen though the BMX bars, moped shocks, and even the vented number plate was the KEZ owned years only, The "EZ rider" name did remain with the mini bike line
From what I have seen the KEZ branded id decals were placed on the headtube so you may find something there, I would be interested if its there to see if it says KEZ or Dailex only because the one thing you may have spotted on yours that varies from the 2 catalog photos is your does not have folding pegs, which may make it earlier....or even later. From what I have seen though the BMX bars, moped shocks, and even the vented number plate was the KEZ owned years only, The "EZ rider" name did remain with the mini bike line