I have a sportster 1200 (95) with shorty super E. Running very rich no matter how you adjust it. Jets are: Main-.068, inter-.028 & main air bleed is .040. Backfiring, smoking and is barely ridable. Any suggestions other than professional help?!

 

Check float level and the needle and seat for damage

 

Check the enrichener too.

 

Here is the 64,000 dollar question. What pipes are you running??

 

The biggest problem with a S&S carb is it is only a two circuit carb as you see with your listing of the jet sizes. I also suggest to make sure your float level is correct as gtrracer said and as Larry said make sure the enrichment is seated.
The intermediate jet fuels the engine up to 3500 rpms, the main jet starts fueling at 3000 rpms and continues up from there. The problem area is where both jets are metering fuel at the same time, which in a smaller displacement motor like the 1200Sporty, makes for a VERY rich condition right where the bike wants to run all the time. If you lean out the intermediate jet to fix the rich area it won't what to run in the lower rpm area....if you try leaning out the main jet to rid the bike of the rich condition at 3000~3500rpm the bike will break up on top end. So how do we fix this problem.....what needs to be done is to have the main jet come on circuit later in the rpm band and we do this with the air bleed youmentioned.The air bleed controls how much air is getting into the main jet circuit, this works a lot like this......amagine you where drinking a glass of water with a straw, as you suckon the straw the water comes up and out very easily, now if you put a hole in the straw you would find it harder to get the water out of the glass. The air bleed is that hole in the straw, so the bigger you make that hole (air bleed) the later the main jet supplies fuel because it takes more air rushing through the venture to draw it out. Now I can tell you a .040 air bleed is stock(since you listed the air bleedI take it it is adjustable by removing and replacing it with a bigger hole) try a.068 for starters, if the bike starts to break up on top end install a one size larger main jet.
This should be done on a dyno so you can see the AFR graph because when you get the air bleed correct you will see in the graph the rich dip in the fuel line at 3000~3500 rpm is gone....if notmake a bigger hole in thestraw.
This condition isn't too bad in a larger displacement engine but it sure shows up in the 1000~1200 sportys.
Hope this helps.
Doc

 

Hello,
I use Ozlogin post because I thing that my problem is nearly the same. Sorry if i don't use the correct expression.
The carburator a s&s super E. The engine is a 96ci compression: 10.2:1
Main jet is a 74 and 31 for the intermediate. There is a yost power tube in main jet tube. I don't have an adjustable main air bleed . the exausts are supertrapp with tuning trapp.

When I ride at nearly 65miles/h - 3000-3500tr/mn nearly, fifth gear, and when i accelerate fast (like if i want overtake fast a car)the bike doesn't accelerate as if there was to much petrol arriving! When I accelerate slowly, there are no problem! I have put smaller and bigger main jet, but it's the same problem.
If I take off the air filter, everything is ok!
If I take off all trapps in the exaust it's ok too, but it is really too noisy.
What could be the problem? Is the .031 intermediat e too big. (I have never put a smaller)
Is the main air bleed is to small? If I have understand your post Doc 1, it is the problem.
If the .040 main air bleed is too small, S&S say to drill a bigger .048, but how could I do ? is there only one drill to be done or more? Is the holl is straight?
Thank for your help.

dider

 

Not exactly sure type of pipes. They were on the bike when i bought it. They,re not stock. I think they are just basic straight pipes.

 

avalon
Try a 29.5 first. If it runs good without the air cleaner try running it with the cover on but without the element. I've seen them where they were over-oiled & choking the motor. As far as the air bleed goes you can try drilling it first & if that doesn't work convert it to an adjustable.Try a 68 like Doc said.
I run a 72 air bleed on mine. [88" Evo]
oz
Those straight pipes are killing you.

 

Thanks to all for the great info! Will post what ends up working.
ozlogin