I know this is a bit late but I've fitted a sidecar to the left of my ETZ250, its crude but structural, functional and fun.
Been running it for the last 2 years with no real problems other than the occasional kickstart frustration, the main
problem is I had to put one of the main mounts directly under the start lever which means it only travels about
half way so you can never get a full kick, instead I have to give it 3-4 small kicks to prime it and give it 1 big kick
as soon as I feel compression and it mostly starts "1st" kick unless I've done something stupid like left the fuel switched on
overnight or accidentally let go of the choke lever.
I'm new to this forum so not sure if i'm allowed to post links but heres an overview of my build:
http://www.advrider.com/forums/showthread.php?t=916978