Have a WR426 and it has had the timing changed to that of a YZ engine and it has a YZ exhaust. I was thinking about putting the stock exhaust back on it to make it a little quieter, as i find it is annoying.The rediculous bung at the tail of the stock exhaust has been removed(ie the one that reduces the hole to 1cm).I never ride it on the road. The pipe has been repacked so it is as yamaha had designed it. Is it a bad idea to put the original exhaust back on with YZ timing? What should i do with the jetting also?From memory the needle clip was still in the stock position. If it makes any difference it does backfire and play up at altitude which i thought was a bit par for the course. Any help greatly appreciated.
