Experimenting with different pipes, and tried to readjust the idle mixture. The screw didn't change anything, even all the way seated. So I took the air cleaner off and fired it up to see where it was getting it's fuel from. Couldn't see anything at idle, but just off idle I could see fuel coming up through the main jet. Is there anything besides a high float level that could cause this? I set the float by the book (on my drill press table at the correct angle), so I think it should be ok. It's got a 45 pilot jet, 180 main & the '88 Sportster needle.
The bike runs good, but I think it could be better.
Any ideas before I start tearing into it, so I know what to look for?

 

What do the plugs look like? Do you think you are too rich, or too lean?

 

let me start by saying that I am a carb terrorist...I have never been able to get one right. I dyno sh** now. how ever, per my OEM manual, If you seat the A/F screw and the bike still does not respond you need the next smaller jet. maybe a 46.

 

Not exactly sure what a "carb terrorist" is, but swapping from a 45 pilot jet to a bigger 46 pilot jet means it will only get richer.

The Sportster needle definitely works to richen-up everything at idle, off idle and up to 3K rpm. It does get a little lean under load at 3K rpm, so beware of the dreaded ping. Many guys like to use the NOKK needle instead b/c it's rich enough down low and offers a richer transition @ 3k rpm under load to avoid the ping. Often, the "lightly seating then backing out" technique doesn't register hesitation when using the richer Sportster or the NOKK needles. Just seat it, then back out the idle mixture scew 2 and 1/4 turns, and you should be fine. Run it on a Dyno to get your AFR. Remember the MoCo produces them very lean, so "riching" AFR down to @ 13.5 :1 should give you a good compromise of decent power #'s and decent fuel mileage.

 

Turning air screw in all the way down should have an effect. I would start by looking at your enrichner

 

Turning air screw in all the way down should have an effect. I would start by looking at your enrichner and make sure it is seating check the cable at the elbow for separation. I wouldn't think a 45 be to rich

 

Cleaned out all the passages with carb cleaner & compressed air, checked enrichener and everything else I could think of. Put it back together and checked for vacuum leaks. Idle mixture screw still doesn't have any effect on idle. Runs and idles good.
Went for a 300 mile ride yesterday, and she purrs like a kitten, even 2-up going uphill.
Plugs are tan-colored, so it might be a tad rich.
Thanks for the info on the needles, Mr. Butler.
I think it's as close as it's gonna get without a good dyno tune. Thanks for the suggestions!