I've been hesitant to post this because I know it's one of those difficult things to diagnose via the internet, but I've pulled my hair out for 6 months now chasing an intermittent carb cough problem. I've also seesawed between whether I'm fighting and ignition or intake issue and in the process thrown a lot of (on-hand spare) ignition parts at the problem to no avail.
The cough occurs most often at idle, like sitting at a stop light, and will usually happen anywhere from every 15 - 60 seconds. It also occurs occasionally at steady, low load, speeds, like cruising at 45mph in 3rd gear, but not near as frequently as at idle. May happen 2-3 times an hour at a steady 45mph cruise.
Cruising 70-80 mph on the slab it never misses a beat, that I can detect.
While of the mindset that it might be an ignition problem, I replaced multiple sets of plugs (DCPR7E & DCPR8E), plug wires, coil and CKP.
The carb (CV40) has been off, cleaned and rebuilt twice, including a new slide, jets, needle, E-tube, accel pump, etc. Also replaced carb to manifold boot again.
The bike has been dyno'd and well tuned. My dyno guy as well as myself have been over the bike with propane looking for an intake leak and found nothing.
Now just for the back-story and not that I'm implying that it has anything to do with it, this problem started after the bike was down for 2 months doing my 1250 build and has been present since start-up.
Other than the cough, the bike runs great and plugs look good.
I'm out of ideas, so if someone has any, I'm all ears.
Other Info:
The 1250 build was done at 92,000 miles, I'm now at 98,000.
MAP sensor was replaced at 80,000 miles.
Running Rico's - Jester Motorwerkz Smokeover RR-1250 map
All vacuum hoses replaced during rebuild.
Thanks
The cough occurs most often at idle, like sitting at a stop light, and will usually happen anywhere from every 15 - 60 seconds. It also occurs occasionally at steady, low load, speeds, like cruising at 45mph in 3rd gear, but not near as frequently as at idle. May happen 2-3 times an hour at a steady 45mph cruise.
Cruising 70-80 mph on the slab it never misses a beat, that I can detect.
While of the mindset that it might be an ignition problem, I replaced multiple sets of plugs (DCPR7E & DCPR8E), plug wires, coil and CKP.
The carb (CV40) has been off, cleaned and rebuilt twice, including a new slide, jets, needle, E-tube, accel pump, etc. Also replaced carb to manifold boot again.
The bike has been dyno'd and well tuned. My dyno guy as well as myself have been over the bike with propane looking for an intake leak and found nothing.
Now just for the back-story and not that I'm implying that it has anything to do with it, this problem started after the bike was down for 2 months doing my 1250 build and has been present since start-up.
Other than the cough, the bike runs great and plugs look good.
I'm out of ideas, so if someone has any, I'm all ears.
Other Info:
The 1250 build was done at 92,000 miles, I'm now at 98,000.
MAP sensor was replaced at 80,000 miles.
Running Rico's - Jester Motorwerkz Smokeover RR-1250 map
All vacuum hoses replaced during rebuild.
Thanks