They usually stop making parts for most bikes including bikes that you could go buy at the dealer today a year or 2 after the bikes are produced, I was also told that parts are only availabel for motorcycles because not all the pikes were assembled. So basically there are only parts because they didn´t sell as many bikes as they intended to so the unassembled bikes get sold as part and when they are gone thay are gone. Bikes vary so much from year to year that the ffactories are completely retooled and wheb that happens it isn´t cost effective to retool a machine in order to make old parts. Still for these older bikes ebay is a great place to look and right now there is a guy who has what looks like 2 71 cb450´s in parts for sale right now. Other than that there is a web site called pro source at www.shop.prosaourceoutlet.com that has all the avilable parts for these bikes as far as I can tell. Good luck and keep these great machines running.