Carb cough . . .

Thought I'd start a new thread on this coughing business. Mine has been doing it for a while now, and always when I take off or blip the throttle at idle. It's like it's starved for fuel. This doesn't happen all the time, maybe once or twice during the course of a riding day. Yesterday I opened the air mixture screw several times and it still persisted. So I'm going back to 1 1/2 turns out. Carb has been cleaned. I have a 46 pilot and will try a 48 pilot next as soon as Tattoo can get one. All his jets are on back order.

The Beast runs fine otherwise.

I do have a used 50 pilot that was in my old Keihin butterfly carb. I'm thinking of trying it because some of the boys on the shovelhead forum recommend it with the CV carb. What do youse think?

I'm pretty sure the butterfly carb jets and CV jets aren't interchangeable....

Did you try to turn the mixture screw in until it stumbles,then back it out until it stumbles then split the difference...if you get your best idle at less than 1.5 turns out pilot jet is too big,more than 3.5 turns it's too small....

I'll try that today, thanks. It's getting harder to start after it's warmed up, too. Used to start (when warmed up) in one kick - now I have to clean it out to get it started - sometimes more than once. Going to take the pilot out and check for debris. It's possible it could be clogged, but not likely.

The milage tells me it's time to check the points, so today I'm also going to check the timing and re-gap if needed. Tattoo tells me to switch to EI. But that's not in the budget at this time - too many other things to do first, like rebuild the rear cylinder, change the throwout bearing, try to stop the leak at the cam, install a roller chain, etc.

So, I'm finding out that after a few thousand miles, things change and you have to start over . . . but I've been able to ride this season without too much going wrong and I'm thankful for that.

I'm also fighting that hassle. I got a 1980 thousand CC Ironhead with a S and S super E carb. A drag bike fuel petcock is used to make sure enough gas makes it. When all the adjustments get done the hassle can arize when the carb isn't getting enough gas. The ethanol in poor fuel causes it. I just used some sea foam to clean the carb and fuel filter. It just takes 1/4 cup per gallon.

I have heard that from another rider. A 1/4 cup sounds like an awful lot per gallon, though. I will investigate, thanks Shovelhead13. I didn't have this problem when I finished the build and started riding 3200 miles ago. So I'm thinking it's got to be the fuel, also. Everything else is spot on. I have read that gas companies are putting in as much as 20% or more ethanol in the gas. To me, it's just watered down gas. Those a******s make more $$$ that way, no doubt.

Cowboy, I think I will switch to EI eventually, so long as there aren't any other changes I'll have to make to the electrical system.

Pick-up sensor is the only sensor I liked the switch to...once you do it Joshbob you'll like it...

1oz/gal can use up to 2oz/gal for Seafoam...

Sea Foam | Tech Info - Gas Engines

Not sure what ignition you will need but keep in mind that if and when you do go to an electronic ignition, I have the stock ignition for my Sportster that I will part with for cheap. Just a thought.

Thanks, Johnny. Don't know yet what I'll have to do. Tattoo says he will hook me up when the time comes.

Lucifer, I looked at all the info on the link you supplied and thanks. I will be using the stuff starting next week (SS payday - I may have mentioned it before that I basically built my beloved machine with SS money). I'm going to be looking at a gallon of Sea Foam as it will be cheaper to buy more product. I'm fairly convinced that it is the ethanol fuel that is causing this hesitation and coughing problem. Also, the bike is hard to start after warmup and I never had a problem with that, either, once I got all the mechanical stuff figured out.

My carb didn't cough or hesitate during the first couple thousand miles after I finished the build. Bad gas and/or high ethanol percentages may very likely be the culprits.

The jets I have are 46 & 185, the ones recommended by Ken for my engine. Tattoo says to go up to a 48, but first I'll try the Sea Foam before changing the pilot jet. The larger pilot will be the last resort if all else fails.

JoshBob, I have the same issue with my Road Glide. Every once in a great while I will get a slight cough and that is it. I notice it when I blip the throttle. I chalk this up to that my bike was jetted when it was really hot outside. Now that it is getting cooler, (air density change), I experience this intermittent cough. I am not worried about it and will not mess with it. Why mess with it if happens once in a great while? It really isn't hurting anything.

Mmm . . . Lucas, Redline, Sea Foam. I suppose they are all similar?

Johnny, do you use a fuel additive and still have a coughing carb?

Yeah,they are...here's another product you can add to the list

Star Tron Enzyme Fuel Treatment - Star Tron Story

I use Sea Foam like once a season if I feel the need, otherwise none. I use 92 and up octane gas, most of the time I use a 10% ethanol mix but when I can get non oxygenated I use that.

I really think that if it is coughing once in while, leave it alone. I guess I have another question for you. If I read right, this coughing that you are describing, it is happening when you blip the throttle and at no other time? I am not concerned at that, but if it is coughing while you are at speed or under acceleration, then I would think there is an issue.. JMO

Yep, it's just once in a while when I blip the throttle at low speed, usually when I have the clutch in shifting out of nuetral into first. Never happens at any other time. Still, I'm going to try one of the fuel additives to my gas and see if it gets better. It might not be serious, but it is irritating.