ok, I put my 38mm billet on the 2013 yz250 this morning and.........it works!! At least around my 2 acre yard it seems to run as good or better than before! Ignition mapping seems good. I had to take out the reed spacer to make the overall intake tract a little shorter for spring clearance to carb boot as is common on the yz from what I hear. The boot just touches the spring and moves away as it compresses. When I put the 300 topend back on with st snow kit I will have to reinstall the reed spacer so the piston doesn't munch the reeds, at least that's what I hear will happen on the bigger bore without it. with the 300 topend on and reed spacer back in, the carb will fit fine because the spring will be gone for the strut rod. I looked at cutting down the boot but the way it is made that did not look as clean as on a ktm. It still has plenty of hit on the bottom, plenty to go 12 o'clock with the front at will! I will have to take it out and try it in the woods, but for now I am satisfied!
