my dads didn't come with a yamaha boot, it just came with a boot that lookd like it was made out of radiator hose that was cut and glued together to adapt it to my carb and airbox. i think this is what he has. if that is the case i don't think they sent him the insert to run a 28mm carb. Also it sounds like it is not even in the frame right. He should send us pics of the box and it in the frame so we know how to help.