Carb Farts? Bad gas milage

RinconBeachDude · #1 23rd January 2010

I bought a 2004 1200c about 6 months ago. I love it...! it's Wicked fast, but there are a few things I'm noticing that don't seem quite right.... the first is that sometimes if I roll the throttle quickly "on" then "off" with the clutch in, coming to a stop, I will sometimes get a sucking sound then a pop... like the motor is gasping to breath then burps... is this what I read to be carb farts? and the other thing is that I'm getting 40 mpg, which I figured was normal for a performance bike like the sportster.... but after reading many posts seems I should be closer to 50..!?

thanks for any suggestions and clarifications

Don Burton · #2 23rd January 2010

Quote:

Originally Posted by RinconBeachDude

I bought a 2004 1200c about 6 months ago. I love it...! it's Wicked fast, but there are a few things I'm noticing that don't seem quite right.... the first is that sometimes if I roll the throttle quickly "on" then "off" with the clutch in, coming to a stop, I will sometimes get a sucking sound then a pop... like the motor is gasping to breath then burps... is this what I read to be carb farts? and the other thing is that I'm getting 40 mpg, which I figured was normal for a performance bike like the sportster.... but after reading many posts seems I should be closer to 50..!?

thanks for any suggestions and clarifications

A carb fart occurs when you open up the throttle and it pops through the carb instead of making power. With a 1200, 40 mpg around town is great if you're not getting on it too hard. If you get on it hard, you can expect even less. 50 mpg is what you might expect at a 65 mph cruise on a relatively open highway if your bike is jetted properly.

SpartanDen · #3 23rd January 2010

what have you done to it? different mufflers or exhaust? change the air cleaner? you may need to rejet and adjust carb. Usually you'll get carb farts because the jetting is off. read the carb sticky's to see how to jet. if nothing has been done to the carb, you will probably have to go up on both jets and remove the plug covering the idle mixture screw and adjust that.
i have changed mufflers, pipes, air cleaner and went from 45 to 48, 170 to 185 on jets and adjusted air fuel. this all but eliminated carb farts. Usually carb farts are a result of rich condition and popping from exhaust is from lean conditions. Usually, not always! I would definetely check your jets and change them...they are relatively inexpensive.
remember colder weather will bring carb farts on more so than warm weather. plus Sportys tend to be cold blooded.
let us know how it turns out.

oh yeah.... i get 39-42mpg. a lot has to do with your right wrist. on the highway i'm pushing 50-52...longer rides steady speed.

RinconBeachDude · #4 23rd January 2010

Hi Denny,

I'm not completely sure what my bike has exactly for performance mods... I bought it used and the salesman told me it has all SE parts... what I can see is SE silp-on muffs, SE Orange wires/Plugs, SE A/C... thats all I can tell without removing stuff... It is definetly cold blooded, I have to let her warm up for 10 mins before riding... once she's warm though she Screams..!!! So I'm just now getting into how to work on it... I do have the factory shop manual, do you find it a good guide???
any ideas on the best way to begin checking the carb settings out would be appreciated!!
Thanks,
RBD

nmbillb · #5 23rd January 2010

Something else to consider. I find that during the winter, I lose 8 to 10 mpg, due to 2 things. One, having to let my '99 883c warm up, and having to use oxygenated &/or ethenol blended fuel. Every year I notice the drop in mileage and worry, but then spring comes around and the mileage goes back up.
About the only way that I know of to check the jetting on the carb is to pull the carb and pull it apart and visually look at the jets.
Good luck,
Bill

RinconBeachDude · #6 23rd January 2010

Thanks Bill... I live in southern california in a coastal community. we don't have large temp. swings here... but I think you're right it does look like I'm going to have to take the carb apart to know for sure...

SpartanDen · #7 24th January 2010

Rincon...
can't help much with your air cleaner.... someone may chime in with some suggestions to look for to make sure it is free flowing. The se mufflers should be pretty much straight through...that is no blockages in the flow path. I have supposedly se mufflers, they have a script on them, but I can peek right down through the center...i suspect the packing, if there is (or was) any is long gone!! read the carb sticky's. there are several and they pretty much all say the same thing. but if you read them all you may understand more of what you have and what you want.
You have a bike that is new to you. you do not know much about her. Take some time and get to know her. Buy a factory manual, a 3 ring binder and make notes on everything you do to it. all your changes, what parts installed, keep instruction sheets, copies of what ever. i have printed out and high lighted bits and pieces of some of the stickys and put them into my binder. once you get a manual, and read up on the carb stickys, pop the carb off and have at it. it really isn't hard!!! when you remove the float bowl, replace the screws with some stainless socket head cap screws. m4 x 1/2" or so is what I think it is. this site has much to offer....do a few searches, get into the forums and look at the stickys, and get into your bike!!!
and as always, if you have questions, pop in here. but do not ask which oil, filter, spark plug, gas to use.... those have been brought up so many times some actually seem annoyed!!!! good luck!!

RinconBeachDude · #8 24th January 2010

Thanks Denny... Great advice..! I will get a binder... I already have the shop manual... I just need to read up on all this stuff... I'm good with V8's, so I should be able to handle my Sporty... Thanks for the encouragement..!

mindseye · #9 29th January 2010

pops are cause it is too lean...reset your carb mixture then idle, all will be good....also let sporty warm up before taking off, she doesn't like a cold start, and don't over use the enrichner she doesn't like too much rich either....you will find the sweet spot....every sporty has one.

cysu888 · #10 29th January 2010

40 miles per gallon sounds great to me. For some reason, my sportster is only getting 24mpg. Not sure what is going on.

Its a 2009 883, I've driven it around for only 950 miles so I don't know if I've even hit the break in point. My typical trips are multiple short city rides of 1 or 2 miles and about 10-15 minutes long each.

I have a set of V&H slipon mufflers, SS airfilter, and fuel pak. But the horrible MPG was also an issue before I added all the other components.

Any thoughts if it is that i haven't hit the breakin point or something I should take back the to the dealer to look at.

Thanks.