Unless you can find someone with a 650 Rincon that has the same mods as you do, I doubt if anyone will know what jet size you need. It's a trial and error process. That's where a kit comes in handy, you can keep trying different sizes until you get it right.
Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.