883 Pops back through the Carb
Thread Starter
|
Road Captain
Joined: Mar 2008
Posts: 601
Likes: 6
From: Aruba
883 Pops back through the Carb
Have a 2004 883 Sportster that has always hesitated and popped back through the carb when hitting the throttle from idle speeds. When new, it was pretty bad. Replaced the stock pipes with straight pipes. Replaced the air cleaner with a Kuryakyn Standard Hypercharger and installed the rejet kit for the stock carb. At this point, the bike ran much better than stock, but it still pops back every so often. It doesn't happen a lot, just enough to be really annoying and sound bad. It doesn't take a full crank of the throttle to cause this either, sometimes it happens when cracking the throttle lightly. Usually this is from idle, but sometimes it happens when shifting if the revs get low enough. Plugs look good now unless the girlfriend uses the choke for too long when starting, but I've got her out of that habit now. Plugs are Screaming Eagle.
Pulled the air cleaner and watched the stream from the accelerator pump and noticed that it splashes against the vacuum piston instead of down the venturi. When the engine pops back through the carb when cracking the throttle, it actually spits the gas back out which results in a stain on the chrome air cleaner that needs to be cleaned.
Should the stream from the accelerator pump spray down the venturi or is it correct in hitting the vacuum piston?
If it shouldn't be hitting the piston, how do you adjust it?
Any other ideas to solve the issue?
Thanks much in advance.
Pulled the air cleaner and watched the stream from the accelerator pump and noticed that it splashes against the vacuum piston instead of down the venturi. When the engine pops back through the carb when cracking the throttle, it actually spits the gas back out which results in a stain on the chrome air cleaner that needs to be cleaned.
Should the stream from the accelerator pump spray down the venturi or is it correct in hitting the vacuum piston?
If it shouldn't be hitting the piston, how do you adjust it?
Any other ideas to solve the issue?
Thanks much in advance.
Outstanding HDF Member
Joined: May 2007
Posts: 2,304
Likes: 31
From: Florida
RE: 883 Pops back through the Carb
Popping through the carb is normally a lean condition or retarded timing....in your case I will say it's a lean condition. Replace the pilot jet with a #45, screw the idle mixture screw out two turns from bottomed out. It should be good to go.
The accelerator pump will squirt on the piston unless the bike is running.....when the bike is running and you gun the throttle the slide lifts up and the squirt gun should hit the needle to start it to atomize as the gas is pulled in.
BTW welcome to the forum
The accelerator pump will squirt on the piston unless the bike is running.....when the bike is running and you gun the throttle the slide lifts up and the squirt gun should hit the needle to start it to atomize as the gas is pulled in.
BTW welcome to the forum
Thread Starter
|
Road Captain
Joined: Mar 2008
Posts: 601
Likes: 6
From: Aruba
RE: 883 Pops back through the Carb
Thanks for the welcome.
I did replace the pilot jet with the #45 that came with the kit. I have also run the idle adjustment screw all over the place but that doesn't fix the issue. Started out with the screw 1 1/2 turns out and ran it in until the motor stumbled. Did the same turning it out, then set it 1/2 between those two points. Still get the farts. Since then I have tweaked and tweaked. I have gotten it better, but I cannot eliminate the problem.
With the bike running, the spray still hits the slide.
I did replace the pilot jet with the #45 that came with the kit. I have also run the idle adjustment screw all over the place but that doesn't fix the issue. Started out with the screw 1 1/2 turns out and ran it in until the motor stumbled. Did the same turning it out, then set it 1/2 between those two points. Still get the farts. Since then I have tweaked and tweaked. I have gotten it better, but I cannot eliminate the problem.
With the bike running, the spray still hits the slide.
Outstanding HDF Member
Joined: May 2007
Posts: 2,304
Likes: 31
From: Florida
RE: 883 Pops back through the Carb
If the slide isn't giong up check the diapharm for a hole or a tear. If the bike is still spitting advance your ignition timing a couple of degrees....that should stop it. I only do this after the carb is all set up correctly.
Good Luck
Good Luck
Thread
Thread Starter
Forum
Replies
Last Post
Blacksport97
Sportster Models
13
Jul 7, 2020 02:02 PM
Alex Van Tress
Carburetor Related
4
Mar 11, 2018 03:40 PM
diddlyd
Carburetor Related
2
Dec 19, 2015 11:17 PM
