Well, you can try a different jet. Most carbs come with jets that are too rich. If you don't want to drill your own here are some you can try.
http://www.ebay.com/itm/Set-Of-5-Je...945707?hash=item3f37abcd2b:g:oREAAOxyJypTlHm0
http://www.ebay.com/itm/MOTORIZED-B...ash=item419b5ce8a7:g:~kUAAOSwPcVV16dE&vxp=mtr
http://www.ebay.com/itm/Set-Of-5-Je...945707?hash=item3f37abcd2b:g:oREAAOxyJypTlHm0
http://www.ebay.com/itm/MOTORIZED-B...ash=item419b5ce8a7:g:~kUAAOSwPcVV16dE&vxp=mtr