try 2nd or 3rd gear and try and put as much weight back as far as u can. But be careful if your giving it some throttle so that when it starts u dont flip it.
Yeah i normally try'd 2nd or 3rd when jump starting but soon gave up... my mates has the same thumpy and i can jump start his not a problem... He's broken the kick start gears so it has to be jump started..