I have a 99 yz400 plated, just switched to sm tires.
Its seems to have a lot of up and down chain slap, does that seem normal, im running an o-ring chain, and its adjusted to spec.
any sugestions, mabe a non oring chain?
up and down isn't gonna hurt much unless your chain is skipping teeth. are you running a chain block, not sure if your bike came with one or if it was taken off? did you set slack with rider on the bike? a non-o ring chain wouldn't help with up and down slap but it would be thinner and prevent clearance issues.