Can't tighten caliper nuts - Help!

I took my KZ1000ST out for its first spring ride a few weeks ago and partway down the road the four nuts for the caliper bolts (that hold the calipers together, not onto the forks) all parted company. Fortunately made it home without any problems. I bought some nuts and tried to tighten it all up but on a few of the bolts even when I have the nuts tightened on as much as possible, there is still about 1/4 inch of movement side to side on the bolt (it is not tight to the body of the caliper). Anyone know why this is or how I would fix it? Don't want to ride at the moment in case my calipers split apart and I'm pretty sure that they weren't 'floating calipers' originally.

Tim

Are you sure that the new nuts are correct? Take a bolt out and make sure you can turn the nut by hand for the whole threaded area.

I took another look at my parts diagram and I see I'm actually missing some spacers that are supposed to go behind the nuts (must also have parted company at 75mph) so I'll have to throw some washers in there. Thanks though Faffi, I did think maybe the outer diameter of the nuts was wrong (the thread pitch is correct) so I tried 3 or 4 different sizes with the same result.