why would the exhaust have anything to do with starting? is it still disconnected? "VERY hard to start" meaning it eventually started or hasn't since the exhaust work? still 6V or converted to 12? have you checked if it's getting gas?
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics