Hi, I'm new to this and buildin bikes. I have a 85 iron and it a lil gutless when its under a load (with passenger) . Ive seen talk bout head wrk, ignition, or a bore job. Although I don't know which will help more. Love my bike and don't wanna get rid of it for a bigger one but all I ride with have big bikes and I can't keep up. So thought upgrades would help.