Coughing when pulling away
I'm having a issue with my 2005 VTX 1300. When I pull away it coughs and splutters. It isn't as bad when the bike is on the side stand, worse under load. I will have to nurse the throttle gently for it to pick up and go, once it's on the main jet it pulls great. However if I pull the choke out the tiniest bit the throttle reaction is how it should be, revs up great, but then it coughs out black smoke from the pipes.
The bike is completely standard, standard pipes and filter. 55 pilot jet, 190 main jet. A/F 2 1/4 turns. 5,000 miles, fresh petrol. Carb has been cleaned, no air leaks showing when spraying easy start around the intake. Diaphragm is good with no cracks or holes. Needle is standard so no shims.
If I drip petrol into the carb it will pick up and respond as it should, meaning it is running lean. Plugs tell a different story, black around the base and tips.
I had the exact same symptoms on a Harley XL 1200 where the CKP had gone. It's that exchange of coming off the pilot and onto the main jet, it didn't know when to advance. Since the VTX doesn't have a crank sensor I thought I would disconnect the TPS to see if changed the bikes habits, hoping it would be the same and buy a new TPS. When disconnected it ran even worse so the TPS seems to be working.
Do you guys have any ideas on this? Any input would be greatly appreciated!