Who is running a flat side mikuni on their Iron Head and which one you running. Ive heard they are the best thing out there and a 38mm would work best for the old Irons but talk is cheap and I'd like to hear from some experienced people who are actually running one before I drop a chunk of change on somthing i dont know anything about.
i was just given one off a running bike.. i really dont know how size it is or anything, my bike isnt fully together yet to get it running either... it is the carb i plan on using but no reviews yet, sorry
I haven't had experience with the flatslides on harleys, but would also suggest 38, perhaps 40 if your engine has strong performance mods. I think it's better not to over-carb a bike. This is what my own research has shown - your mileage may vary. Some flat track racers seem to use the 38 round slide on their KRs, and I have a 36 set aside for my (street) KH at the moment. I would imagine you'd want to go bigger for the ironhead, but then at the same time stay somewhat conservative due to the flat slide carb - so 38 sounds about right as you said. One thing I have found is that the throttle action/response is somewhat different on flatslide carbs, usually heavier and requiring more controlled throttle management / roll-on for best effect. Not good for traffic riding, but you should be ok with a single carb - mine were on inline fours etc, so I imagine it's easier with one!
I'm leaning towards the 38mm now. I found a place that carries them out of Florida in both the flat slide and the round slide version. Ive heard the 38mm are the ticket for the old iron Heads, they are suppose to be just right on. Like you said anything else is over kill. The CV I have now works pretty good but not great and Ive never really been happy with it. A 38mm flat slide is like a $181.95 plus about $10.00 sgipping. So its not like a huge investment.