i have done king size quilts on my Kenmore sewing machine , but i do it in a quilt in a section way i read this a few years back and it works !!
lay out the quilt with all 3 layers top on the top of the pile,9make sure the batting and the bottom are a couple inches bigger than the top) i only use spray basting (no pins for me)take the top layer and neatly fold it back, so you only have the batting and the backing laying there, look at the quilt and divide the batting sections into what you think would fit under your machine nicely one at a time , but make sure you have a middle section, then cut the batting ONLY becareful not to cut into the backing in sections before removing the sections mark with a pencil how they go back together ie far left 1 of 4 sections ect then take out the extra cut batting sections but leave the one that is in the middle (always start in the middle), now spray baste the middle backing to the middle of the back of your quilt, then spray the top of your batting , the one you just sprayed to the backing ,and pull the top over and it will stick to your batting , so now you have your quilt with only the middle section with 3 layers roll up the ends and quilt that section but stay only where there a the 3 layers dont wonder of , after that section is done lay quilt back out and add the next section to either side do the same , quilt it and then get another section spray it down quilt it and then you are done !!!
always start in the middle and work your way out!!