Hey guys, I've been working at this for a while now and I'm about to throw in the towel and take it to a shop, I'm out of ideas. Here's what I've got:

2006 FXSTB with CV Carb running a 48 slow jet and a 195 main jet.
V&H Short Shot pipes.
Performance Machines Air Cleaner
88TC with 501 S&S Cams
Pingel petcock with no vacuum tube (port is capped off securely on carb)


Here is what the bike is doing:

Cranks up fine, using the enricher to help bring engine up to temp. Once operating for 5 minutes I shut enricher off and bike idles fine. Take it for a spin around the block (approximately 10-15 minutes) and come to a stop and the bike starts idling rough and then will choke out. Sometimes when I give it gas from idle it will choke but then pull through. Once I have given it gas and it is above 1500 RPM's she runs like a scalded dog, no issues what so ever.

Here's an interesting thing I noticed today. When it is hot and idling roughly it will bounce between 800-1000 RPM's, if I blip the throttle the RPMS' will maintain around 1200-1400 RPM's for a couple of seconds after I have released the throttle and then it will fall back down to 800-1000 RPM's and idle rough until it finally cuts out. I am experiencing no carb fart at this time.

Here is what I have done:
Tore down and cleaned the carb twice including spending extra care and time cleaning the needles, jets, and emulsion tube and pinholes. Used carb cleaner and an air compressor with a toothbrush. Made sure the slide diaphragm has no holes or cracks in it. It is fairly new and very pliable.

Replaced spark plugs with brand new plugs, here are the old ones I pulled out. Left one is my front cylinder, Right is my back.


Used propane every place I can access that could potentially be a vacuum leak (main intake seal, enrichment cable connection, vacuum port, all areas around carb)

Drained the gas tank completely, added fresh gas and some seafoam .

My idle mixture screw is currently set at 2.5 turns.Throttle cable is smooth and not sticking even when RPM's are higher at idle.Very little slack in the cable.

What I haven't done yet that I was thinking about was pulling the spark cables while the bike is running to see how it reacts, but would there even be a coil or cable issue if the bike runs great at higher RPM's? At this point I'd pull my hair out but I dont have any lol. I am mechanically inclined and work on all kinds of things but I am no master at this, I appreciate anything that can point me in a direction. Is there any sensors or anything I am unaware of that would cause this issue? At this point I don't think I have an ignition issue, a fuel issue, or a carb issue so in my mind I should not have an issue Obviously I am missing something or I am ignorant. Please spare me from my misery....

 

Huh. I'll try to help, not sure I can; been a long time since I played with carbs. Sounds like you've done everything I would do. From your description, sounds like it's low on gas or too much air from a vacuum leak. I know, you checked for that. When you cleaned the carb, did you rebuild/replace o-ring/gaskets etc..? Sometimes a leaky accelerator pump can cause this. Does bike have a VOS (vacuum operated switch)? Vacuum piston good? Float level correct? Float pin worn? Float needle sticking? Clogged fuel filter? Gunk in bottom of tank?

If it were me, I'd go back to square one and set idle mixture screw/idle adjustment etc.. Start at 1 1/2 turns out, see if that works, if not go 2, etc.. Sometimes thing run well with storage settings. If that does not fix it do a complete carb rebuild.

Best of luck.

 

Thx for the reply, when I tore down and cleaned the carb I also replaced all gaskets and float pin. Also set the bowl float to spec with the service manual. The bike does not have a VOES anymore, it was removed when the pingel petcock was installed, the vacuum port on the carb has been capped off.

Would my slide needle height have any effect? It is adjustable but I have never adjusted it. I t is set right in the middle of the grooves, there were no washers above the clip (that I remember seeing...lol)

 

So apparently my carbureted bike has a MAP sensor on the intake.....strange.

Anyone know if this could cause symptoms like mine? Only other sensor I can find is the Crank Positioning Sensor. I don't seem to have a temp sensor that I can see.

 

The 48 pilot is likely to much, at least it was on mine. Try a 46 at 2 turns for a start.

 

All a carbed MAP sensor does is retard timing at low vacuum manifold settings (open throttle). No temp sensor on carbed bikes.
As another member stated, take out #48, replace with #46, you should feel an improvement, may even drop further with a #45. Your plugs look rich.

 

Ok I'll pick up a 46 tomorrow and see how it works. I've owned the bike for 4 years with no issues out of the 48 but at this point I'm willing to throw logic out the window.

Made some adjustments last night without much success, and now I've got a squeaking noise coming from the rear left, sounds like possibly the belt as the squeaking slows as the bike slows. Ill put it on the jack to figure that one out. When it rains it pours...

 

Here's one little thing that get's past up a lot ---- did you pull out a little O-Ring that's under a washer that's under the spring at the idle mixture screw ???? it will rot and pass air that makes the engine run like sh-- . Take a paper clip strighten it out - bend a 90 deg at 1 end and cut off till about 1/16 " reach down the hole till you get the washer and O-Ring , use a small dab of light grease to install them

 

Curious as to how you made out..

If you want to see if it's running lean or rich you can hook up a Propane bottle to a vacuum port on the intake and slowly crack the valve at idle, If the idle goes up then it's running lean. If the idle goes down, it's running rich...

When the idle circuit is adjusted properly it should increase 50 rpm with a slight amount of propane..

 

Just a suggestion , but I had the enrichener valve leaking at one time .
clean it , inspect it and or replace it .
also look at the "seat" in the carb