Have a 2003 Sporty XL 1200s Sport Anniversary Edition that stalls at the light or sometimes catches itself and keeps running with a big dip in RPM's. It throws a CEL which shuts off in a few seconds. If I rev to 1500 and ease off clutch, it seems ok. Had the carb rebuilt, changed all vacuum lines, has fuel filter, Replaced the Ignition module under the seat...runs like a beast over 1500 RPM's to WOT. Gives big pops, then dies when accelerating hard off from stop. What am I missing? Thanks in advance

 

How about spark plug wires and connections? Might be worth giving them a check

 

Who rebuilt and set up the carb? Can't be low voltage if it starts.
Gotta be an easy fix.
Is it popping back through the carb like water in the fuel?

 

Thanks for the Welcome. Just changed wires to 8.8mm Drag Specialties set...new plugs also. Had a guy in Cali rebuild them. Send them to him, sends them back. Hadn't thought of water in the tank. Had the bike since Dec. and it started doing this about 2 weeks ago. Driving me mad. May just have to take her to the dealer and wire her up to the Scanalyzer for a diagnosis. Could it be cam sensor, MAP sensor...getting good gas flow. Only boggs when at a light waiting and when I take off letting the revs drop below 1200-1300 and throws a CEL. She runs great at speed...not a hiccup at all.

 

How about if you pull the choke out a little when the RPM is below 1200 and see
if it likes the extra fuel.

 

So it has carbs, right ? And does that while on traffic ligths, waiting for them to change ?
Try giving revs while you wait for the lights to change, so use the throttle a bit while you wait.
I had this type or similar problem on my previous bike, I stopped to lights, letting it idle, lights changed, revved up, let the clutch and.... SMOOOOCH.... stalled ! I got a tip from friend to use the throttle a bit while I was standing and waiting for the lights to change and it did help. In my case it had something to with the carb bowl not filling when idling or something like that. Revving a bit while waiting kept the bowl in carb filled and no stalling !
Worth trying ?

 

Crank Position Sensor

 

Thanks eki912...I was thinking something like that myself. Sounds like a fuel issue. Maybe go in and adjust the float a notch and/or replace the vacuum petcock with a manual one. When it dips in rpm's it throws a CEL but was unable to retrieve a code when diagnosing. As stated, when REV's are up she screams but never fails to embarrass at a stop light. Tried keeping the reves up but when it came time to take off, POP, BOOM, BAM..and that can be downright dangerous making a left turn at an intersection. ---Stereoguy, did you say it was your cam position sensor causing your grief?

T-Jerry, I'm running a 45 pilot and 195 main in the 1200s. I was thinking going up to 48 pilot and see what shakes. Now I have the a/f screw out about 3 turns. I'll try the choke thing next ride. Gotta figure this out, taking the fun outta my day. I have to stay on the highway to ride ok

 

Couple years ago, same symptoms being described, changed it problem solved. Reoccurring problem with these, my sons failed too.

 

I did pick one up last week NOS in the Harley packaging. Did you change the rotor also or those thing don't go bad? Thanks again for your input.