The most reasonably priced component used on the Ch125c 1985 (f) Japan Jf02-130 E-5 is the Pivot,cam Chain.
Parts such as the E-5: Chain,cam, Pivot,cam Chain, Chain,cam (94t), Tensioner.cam are included in the Ch125c 1985 (f) Japan Jf02-130 E-5 parts fiche.
