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Carb swap advice for the 2004 Sportster 1200

throttlesoulclub126

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Jul 8, 2025
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Hey everyone, I'm trying to get my friend's 2004 Sportster 1200 back in shape after it's been sitting for a couple of years. The carb has started leaking pretty badly and it's popping when I throttle.

I got my hands on a replacement CV carb, but before I install it, I thought I'd ask for some advice. Is there anything particular I should look at or replace while I'm working on it? I'd really appreciate any suggestions if you were in my shoes.
 
Before you bolt it on, have a look at the intake seals and clean out the jets just to be safe. Also, don't forget that you have to ensure the throttle cables line up correctly with the new carb.
 
Hey everyone, I'm trying to get my friend's 2004 Sportster 1200 back in shape after it's been sitting for a couple of years. The carb has started leaking pretty badly and it's popping when I throttle.

I got my hands on a replacement CV carb, but before I install it, I thought I'd ask for some advice. Is there anything particular I should look at or replace while I'm working on it? I'd really appreciate any suggestions if you were in my shoes.
That sounds like dried out seals and jets gummed up from old gas but it's good you've already found a replacement CV carb. I think that's a solid choice, especially since you won't have to mess with a bunch of tuning for a stock or near-stock setup.

Before you slap that new carb on, definitely pull the bowl off and give it a good visual inspection! Check that the floats move freely and the needle valve seats properly. You might also want to replace the bowl gasket and the intake manifold-to-carb gasket, just to be safe. They're cheap parts but can save you a headache later. While you have the old one off, check the intake manifold for any cracks, especially around the rubber seal. A vacuum leak there will cause that popping you're talking about. Good luck!
 
That sounds like dried out seals and jets gummed up from old gas but it's good you've already found a replacement CV carb. I think that's a solid choice, especially since you won't have to mess with a bunch of tuning for a stock or near-stock setup.

Before you slap that new carb on, definitely pull the bowl off and give it a good visual inspection! Check that the floats move freely and the needle valve seats properly. You might also want to replace the bowl gasket and the intake manifold-to-carb gasket, just to be safe. They're cheap parts but can save you a headache later. While you have the old one off, check the intake manifold for any cracks, especially around the rubber seal. A vacuum leak there will cause that popping you're talking about. Good luck!
I agree. But a couple of tips from me are to don't just check the old intake manifold for cracks, always use a brand new intake manifold gasket kit when installing the new carb. It's the most common point for a vacuum leak, which is what causes that popping sound.
also, check for vacuum leaks. After you install the new carb and fire up the bike, spray a little bit of carburetor cleaner around the intake manifold. If the engine idle changes, you have a vacuum leak and need to re seat the manifold.
 
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