Ok, new to the forum
New bike for me, 98 FLHTC
S&S carb

This my first S&S on an Evo, had one on my Shovel and don't recall as much backfiring and sputtering. When starting up, with the enricher on, the bike will sputter on occasion till warm. Also seems to be a few flat spots on occasion when riding at slower speeds. It backfires when ever I let off the throttle after the bike is warmed up. The plugs shows just a little bit of white at the tip, and dark on the threads certainly not the nice tan look. I sprayed WD40 in and around the intake manifold and no change. Tonight I'll check all the exhaust bolts.

So is this the "norm" for an S&S or could I have an air leak or jetting issue?
What's my next step after I know all my exhaust bolts are tight?
I kinda miss my trouble free CV carb on my Heritage Softail.
Will this S&S perform as nice as my CV when I head up to higher altitudes when I travel to the mountains?

 

Sounds like a lean condition to me. Check your fuel/air mixture screw, intakes, and what jets are in it.

I personally think my bike runs better with the S&S than the CV carburetor. Yes I know it uses more fuel but I have had less problems with it than the CV.

This may help

http://www.sscycle.com/carbquickguide/

 

Coughing back through the air intake is too lean. Out the tail pipe can be several things, but an exhaust leak sucking in cold air in my experience.

It sounds like you may need to back the idle mixture screw out a little bit. Try 1/8th turn and see how that does. Wait for the bike to fully warm up, like 20 miles or so before judging. Try a little more. Or try turning it in, but only judge how it's running when fully warm. If that doesn't fix it, then I'd say you probably need to go one size up on the intermediate jet, assuming nothing is blocked/gunked up.

The tuning instructions from S&S are the way to go.

I've had no problems with mine up at altitude. I usually just turn the idle mixture in a little bit if I'm up there. Walk by many a twinkie with their one-size-fits-all EFI system. They run so pig rich at altitude they can't get out of their own way. Maybe the newer ones are better.

 

Thank you both for the input, that link is great. I have it bookmarked.
Well 1/8" turn helped, now I have just a little growling coming outa the tailpipe, so I have backed it off another 1/16". I should have it dialed in today.

 

The standard idle-mixture screw setting is 1.5-turns out. Try that and go from there...What model S&S carb?

 

It's an "E" carb and I got her dialed in now. She is running like a top and the last tank of gas got 44 mpg. Yeeeeeeeeeeee Hawwwwwwwww

 

You are now ready to open a bike shop! Bookmark the link below for future reference!
http://www.sscycle.com/carbquickguide/

 

Just want to update you all on my S&S carb issue. It was still sputtering and spitting but only on occasion. When I got a new tire I talked it over with my Indy wrench and he recommended replacing the S&S with a CV and Thunderjetting it. Well it's good that I didn't have the money at the time and talked it over with another Indy that lives farther away. I rode over to the other guy and we took the S&S apart. Cleaned the bowl, adjusted the float, and changed to a larger jet. We installed a "31" jet. All the sputtering is history, the bike now starts great when cold, has excellent throttle response, and I even got 42 mpg on the first tank. The best 40 bucks I spent on this bike.

My point on all of this, is all people have certain biases. People recommend what they know, and can fix, so many times it good to get second opinions.