Carb coughing/sneezing????

[RVH]

First off, I have done the searches...... I have adjusted the carb per SS shorty instructions. .......I have checked for intake leaks....The bike had begin to "spit back" thru the carb a few weeks ago. Nothing has been changed or done to the bike. It has progressively gotten worse. Its to the point now where it cuts off after a minute of running when cranked cold. It'll take a few turns of the motor to crank it when it cuts off. (it has always cranked almost quicker than you could remove your finger from the starter button)After that, it runs decent as it warms up but does continue to sneeze/cough though less frequently the hotter the engine gets. I did notice an oily film on the bottom of the mouth of the carb & into the air filter backing plate . It was very light and did wipe off easily. I have noticed that the idle seemed to have gotten lower on its own as this problem has worsened. I have adjusted it accordingly though and keep it just above 1000 rpm. I dont feel as though rejetting would help because it ran fine for so long. As for the adjustment, I have messed with the air mixture from one extreme to the other while riding. Any ideas?????

 

[Gas Man]

Check this thread first...
http://www.bigdogbiker.com/forums/how/4943-how-adjust-your-carb-check-jetting.html

 

[lee]

maybe you just need to blow some compressed air through the jets - they maybe a little bit clogged. Has the weather there turned colder recently?

 

[RVH]

Thanks Lee. That will be my next step if no one gives me something else to check. Weather has cooled somewhat but yesterday was 85 and it still did it. Seems to only do it at 2500rpms or below and especially when cold and just starting out.

 

[lee]

you might also want to run the hose from the rear head to the air cleaner direct from the head to the ground. That should help clear up your oily deposits which might have something to do with this.

 

[RVH]

OK guys, I cant explain it but I kept messing with the air/fuel mix. Ended up turning it 3/4 of a turn out and now shes running like a scalded dog again. No decel popping and no cutting off. This 3/4 turn is in addition to the 1-1/4 turns out from the lightly seated position. To anyone experiencing decel popping I recommend turning the air mix screw out in 1/4 turns until it quits. Worked for me.....

 

[rhinoevans]

OK guys, I cant explain it but I kept messing with the air/fuel mix. Ended up turning it 3/4 of a turn out and now shes running like a scalded dog again. No decel popping and no cutting off. This 3/4 turn is in addition to the 1-1/4 turns out from the lightly seated position. To anyone experiencing decel popping I recommend turning the air mix screw out in 1/4 turns until it quits. Worked for me.....

If turning it further counterclockwise works for you, you could also go UP one size jet. Counterclockwise = rich = more gas. Coughing through the carb is lean, and turning CCW or increasing the jet size SHOULD solve you problem. But you already knew all I just said.

 

[RVH]

Thanks rhino. Thats the "cant explain it " part. Its always ran great from the day I bought it. Thats why I never considered changing the jets. If I hadn't seated and adjusted the air mix screw, I would have thought someone just walked by my bike, reached down and turn the screw in a few turns........ Who knows or cares as long as shes scald'n some Harley a$$ again.

 

[V]

Glad you got it straigtened out. Notice you have the Mean mother pipes. When these were put on, the jets should have been changed. The intermediate should have been a 31 and the main a 78. The main may may have to be dialed down a bit but thats what BD sends with the jet kit for the Mean Mother pipes:2thumbs:

 

[Staffy]

My 2 cents....
First - Don't fix what anit broke...:lol:

Next, I have had some valuable input from the forum and here goes...

Nice advise (dogvet) if more that 2 turns OUT (ccw) from the seat go up 1 size on the int. jet (U R just about there :up: :up: ) - the opp is...less than one turn OUT go down 1 size on the int.

Finally - about the oil near the carb.....Just what "lee" suggested...However ask - why is the "head blowing" so much - :lol: :lol: kidding aside, check your oil level, too much? also check the "one way valve" on the breather tube.

 

[RVH]

Thanks guys..... V, I assume that it was jetted (pipes on bike when I purchased) cause she ran so good. I'll definately check the jet sizes if I ever have to fiddle with the carb again. Love the Mothers. Actually took the baffles out for a ride to Hooters Bike nite in Anderson last week(aprox 100 miles) Didn't notice much drop in the torque nor much of an increase in noise. I put them back in cause it does have more of a hollow sound with them out compared to a low tone rumble with them in.

Staffy, I always follow rule #1.
Gonna leave the jetting as is for now because of rule #1. lol
The blowback in the carb didn't appear to be coming from the breather hose ran to the backing plate. The hose comes out high & right and the residue was dead center on the bottom of the carb. Nothing in between. I have cleaned the breather a couple times but never bothered to wipe the residue off. It could have taken many miles to accumulate and wasn't very heavy at all. Seemed to be a little oily but I guess some of it could be from the carb actually backfiring instead of just sneezing from lack of fuel. Oil level is kept at the bottom of the filler neck. I've never had to add any and never over filled. I'll pull the oneway valve and check it. So far, so good. Thanks.

 

[lee]

RVH - I know you have it sorted now but "took the baffles out last week" and "I put them back in" - could this have something to do with the issue???

 

[RVH]

No Lee, I took them out and put them back while it was still running like chit. Been wanting to do that for awhile just to see what they sounded like. And when I say running like chit, I mean still ridable, just not up to scalded dog status. Just got off the dog and shes still good.

 

[lee]

:2thumbs:

 

[RRRUFF]

Bump!