I have a Yamaha DT 125 LC 10 v @ stroke bike.After I replaced the coils,it starts in opposite direction.Is it a problem with the Pulser (timing) coil?

The timing is out Sandeep....   2 or 3 degree BEFORE  t,d.c .   is needed , move the Stator plate, to mark ,,

No that's no problem at all , as long as you don't mind riding in reverse , lol . A friend once had a YB100 which could be bump started backwards . Should have seen peoples faces when they asked for a go !!