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Hey guys, I have a 1998 sportster xl1200c I am running an s&s carb. I have had the bike for about 2.5 years never really had a problem aside from the occasional choke out when I would accelerate, it will run great and then spit before accelerating flawlessly. That I have felt with and like I said it was few and far between when that happend. Recently I am dealing with another problem, I work at 4:30am so I get up warm the bike up for about 10 min, like usual, and tear off to work without problem. Now for some reason when I take of to work after warm up it starts to stutter, pop and sometimes stall out of second gear, even has flame from pipes and carb, cant figure it out, what should I do.!!!
I'd start by cleaning the carb top to bottom with all the passages cleaned out. Manifold gaskets would be a good idea as well and possibly turn down the adjustment on the accelerator pump rod.
Check that vacuum petcock they are known to fail, Id replace it with a Pingel non vacuum one, that is what it sounds like to me, your vacuum petcock is failing, you can also check the vacuum lines going to it
Since going thru all that, I would suggest some new high quality fuel line (unless recently replaced) and probably worth a look at the filter screen in the tank. If your removing the petcock, your right in there anyways. Pull the screen, clean and inspect. Take a look at any of the parts diagrams online and pick up replacement flat rubber seals for that filter screen before taking things apart.
I like using polyurethane fuel line for the vacuum hoses. They last along time. Way longer than rubber based vacuum hose. Get all or potential fuel delivery issues cleared up at the same time as the possible vacuum leaks, and as suggested, go over the carb completely, especially if not done for awhile. Intake seals go bad with age. Get it all done and be done. YD
Last edited by Yankee Dog; Sep 8, 2021 at 03:46 PM.
So fuel lines,petcock,fuel screen, coil, spark plugs, spark plug wires.. all new when I bought the bike I upgraded all of that while doing an ignition, coil, relocation. However I did check the plugs and Im thinking I might be running rich.. lots of dry charcoal suit on them, not wet so no leak. Before I got the bike the S&S carb and high flow S&S manifold were put on within the last 8 to 10 years, but The previous owner barely rode it. I guess after I clean the carb adjust it and put new plugs in it, if it still dose it then I might have to change the manifold gaskits. But hopefully I wont have to go that far.
Nice looking bike.. I really like it..
flames out the exhaust might indicate an ignition problem.. Does it only do it when the engine is warm/hot.. OEM ignition module is in the case cover..
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Acceleration pop stutter and stall
