I was having a little trouble jetting my wr400 with a yz or wr 426 head. I posted in the jetting section and eddie said that I need to alter the CE setup also known as the octopus that the stock wr400 carb (flat fcr)/head utilize. I couldn't find anything that described this modification and I'm beginning to wonder if I do indeed have a 426 head/top end, or if it is all stock wr400 stuff. I feel silly asking, but is there an easy way to determine what head I have? I tried to search, but all I found was a great deal of threads asking about and explaining the differences between the two motors, not how to distinguish them. I suppose once I figure out what I have, I'll then move on to altering the "CE." Thanks, -Alex I'll post pictures of carb and head if needed, as they are both off of the bike at the moment.