I have seen on two separate related answers to the question of sizes of chain used on the 90 Sport. I was wondering if someone can give me the definitive on the chain size? One post said that 90's used 428 chain and another post said that it used 420. I know both have same pitch but different roller size. Since I am missing chain, I would like to be assured of the correct size and maybe length. Can someone please advise of correct size of chain?. Thanks, Mark