Fresh build over winter
120 break in miles

98”
open air box
stage 2 heads / 9. 3 actual cr
S&S 570g cams
Supertrapp 2 into 1 ( closed cap / 16 discs)
50 on pilot 185 on main

starts easy with minimal choke

runs quite well

At 40 degrees ambient it will exhibit a lean cough entering 3rd gear when pulling hard

plugs are whiter than I prefer

to fatten mixture slightly do I ?
52 pilot
190 main
add washer(s) to needle
install the 1988 sportster needle
subtract discs from exhaust


thank you for input

 

I went with the '88 needle and a washer but your situation may be something entirely different. If it pops shifting into gear then your coming off full throttle to closed throttle? That does sound like a lean situation. Does it pop on decel? Are you sure you don't have an intake leak. Most people can't find a leak and just keep throwing more fuel at it. If www.nightrider.com is still up they have some excellent help areas. I chased the same problem for days with my bike and found it was an intake leak. Spray around the carb seals with brake cleaner or use the preferred and less messy method of a propane torch with a hose on the end so you can reach all the places. Just try to stay away from the intake or block it off with a piece of cardboard.

 

sprayed intake after reassembly during break in heat cycles to check for leaks. None found

no pop on decel

does not cough on shifting

more on leveling off to steady throttle “cruise”

 

May be slide/diaphragm issue. Did you do any mods to the slide? Kinda sounds like it's hanging. You may have to double check for pinholes. Also make sure it moves freely. You can do that when it's not running by applying light air pressure to the opening at the top of the throat. (The small curved oval) If you remove the diaphragm slide refrigerate it to shrink it a bit before putting it back. Makes it a lot easier.

 

those are are all excellent suggestions but this stock carb worked perfectly for the past 20 years in its previous 88” stock head 510 cam and 45 pilot jet configuration
it runs QUITE well now
im looking for the last MINOR tweak

 

Sorry, just offering suggestions. 52 pilot is idle/low speed, 190 main is top end. If you didn't change to the tapered needle that may be the fix. Don't try throwing too many things at it all at once. Like I said it worked for me. Carbs can be tricky and if you just had this one apart that kinda sticks out. Also sometimes an old carb can have worn grooves and the slide can actually flutter.

 

Please don`t apologize , again, these are all excellent suggestions
I certainly will only make one change at a time.
Thanks again

 

At only 120 miles, you're not yet totally broken in.

Sure, the cylinders can (and will) get hot very easily, even in cold weather on a new build, but it takes 30 - 40 miles to get your oil and complete engine warm in cold temps. Even then, there's a LOT of difference between 40 degrees air and 75 degrees air. Makes a big difference in jetting for max performance.

A 185 does sound lean for that engine, but honestly, I wouldn't try to tweak it for max or make any major changes to the carb until you get 500+ miles on it and hopefully nearer to an ambient temperature in which you would typically ride.

 

"At 40 degrees ambient it will exhibit a lean cough entering 3rd gear when pulling hard"
This is the part I really don't understand. Only going into 3rd is when it coughs? And exactly how "hard" are you pulling on a fresh rebuild?