Bonneville America Forums Forums Technical Forums General Tech 2005 America "coughs" on acceleration

2005 America, 73500 miles, Procom ignition, otherwise stock.
The bike has developed a "cough" on acceleration under load, such as trying to maintain speeds up slight grades (70 mph or so). Going downhill she accelerates strong with no ill effects. Carbs removed and cleaned twice in last 2 months, gas verified clean, air filter cleaned and treated, (K&N). Can't determine which cylinder the cough is coming from, if not both.
Selected different number on the PROCOM unit, no significant change. Re-programmed PROCOM to default using software from web-site, no change (seems worse). Still have stock plug wires, as dealer wants $81 a piece for them. Any ideas would be appreciated. Will replace plugs and wires tomorrow. Have decided my next bike will be a Heritage Soft tail.....

Will it zip out to well over 80 on a flat road?

Its going too fast to be vacuum IMHO. I assume your TPS is unplugged, Throttle Position Sensor.

Curious to see what happens tomorrow. I don't think its the wires or the plugs or it would fall down on acceleration in lower gears at lower speeds when droning down the road in 3rd or 4th gear.

Sounds more like Throttle position vs. RPMs.

My first suspect is ignition coil if its parts related. But that is just a guess with absolutely no foundation.

Curious to know how if performs flat out and well over 70 under stress in 5th gear.

Have you looked at the vacuum diaphrams at the top of the carbs and make sure they were seated right upon re-assembly? Spray some carb clean around the intake areas with the bike running if the idle changes you have a vacuum leak there.

Slept on it, got a plan together, removed float bowls and jets on each carb and could not see daylight through one of them. Sprayed carb cleaner through both removed jets and reinstalled. Problem completely gone now, the bike runs as good as new, and accelerates strong thru 90 mph (fast enough for me!).
So if your carbureted 790 starts and idles fine, but spits and sputters sporatically under load, it's DEFINITELY a blocked jet. Easy fix, took about 20 minutes. Thanks for the input, sometimes ya just have to back off and sleep on it!

Never push anything through a jet, if it is that clogged replace it.