I currently have an 06 KX450f/06 KX250 conversion. I have a friend with identical conversion, though constructed abit different. My bike has a serious problem off idle to around 3,000 rpms, its just very sluggish and slow to rev. Heres where my problem lies, the other bike the intake tract is just as stock with the reeds and carb close to original location. When my bike was fabbed, the intake tract was done entirely different and uses 2 3/8 inch reed spacers and a 1 inch plastic spacer block. So the reeds are nearly completely out of the cylinder. My guess as to why mine runs so different down low is the reeds/carb are spaced back so far that its hurting the signal in the lower RPMs. I know typically spacing the reeds back offers more lowend, but at some point its gotta be too much? I know this is the 500 forum, but I figured some of you may have experimented with different carb/reed locations. When it was originally built it was spacers x3, then reeds, then boot, then carb. When I reassemble it I`m gonna try reeds first, then all the spacers, then the boot/carb. This will space the carb further from the reeds but get the reeds further into the cylinder. Any thoughts/experiences from anybody?