right i ave come up with a tensioner, got a piece o flat plate inch an a bit by 2inch long drilled an hole near the end welded this to frame,got some threaded bar heated it up bent it into an (L) shape ,found some strong white solid plastic bar, in garage cut a section outa it on the lathe jus so chain sits in it , then nut, washer,plastic bit and another washer an nut,an a blob of weld so it dont work loose, placed bottom end with 2nuts an washer through hole an another washer,an 2nuts on other side of plate an bobs yer uncle i can move it up an down to take up slack
,but on doing this i saw in back street heroe,s a guy had used flat plate on end with a slot cut in plate, allen bolt through what looked like a bearing and it was pushing down on chain not up