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Discussion Starter #1
Hey guys, trying to dial in this s&s. Specs are 99 FXD 88ci .510 cams 2 into 1 exhaust Dynatek ignition. Pilot jet is .0295 main jet 74 air bleed .040. It seems to stumble when giving slight throttle and the exhaust pops when decelerating. If there's anyone with similar build, what jets are you running? Am I running it lean? You have to be pretty aggressive with he decel to make it pop.
 

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Check your exhaust ports/gaskets for leaks. Might want to R&R just to make sure there are none.
 

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1986 FXRSC #3/1250 Original Owner
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Check your exhaust see if the head bolts are tight. See if you have any leaks at the heads. Check for intake leaks even if you just put new seals on them. Clean carb paying attention to small passages. This fuel today can turn and clog a carb quickly and sometimes it takes more than once to clear the small passages. Again the manual tell you how to do this follow it step by step.
How far out is idle needle? Look under idle system notes in manual 1/1/4 to 1 3/4 turns is what they say
Using the procedure in the S&S installation manual shut off accelerator pump. Ride bike, it needs to be hot and roll on the throttle as they tell you a dozen times or more and decide what way you want to go. Dial in intermediate jet first without changing main. Follow their procedure exactly it works. I have not done a new one with the adjustable air bleed so do what they say on that. You have to get intermediate jet right first BEFORE changing the main. Also make sure the jets you have haven't been drilled bigger, the last one I did was.
If I had to guess I would say that a 295 or 31 in the intermediate and a 72 in the main if you were at see level. Less if you are at elevation.


 

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Hey guys, trying to dial in this s&s. Specs are 99 FXD 88ci .510 cams 2 into 1 exhaust Dynatek ignition. Pilot jet is .0295 main jet 74 air bleed .040. It seems to stumble when giving slight throttle and the exhaust pops when decelerating. If there's anyone with similar build, what jets are you running? Am I running it lean? You have to be pretty aggressive with he decel to make it pop.

The responses so far are funny. You have two separate issues; deceleration pop is one and stumble when accelerating is another. Two separate an unrelated issues.

The stumble could be solved by adjusting the accelerator pump, but that could just be a bandaid. I suggest you get a copy of the tuning instruction for that S&S carb and read them.

The deceleration pop could be caused by an exhaust leak or several other issues. You have not provided enough information to really narrow it down.
 

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Isn’t some decel popping normal? I don’t think I’ve ever had a Harley that didn’t have some decel pop haha. Maybe I’ve never been on a properly tuned Harley ?
 

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1986 FXRSC #3/1250 Original Owner
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Exhaust leak are the main cause for decal pops. The head bolts in the pipes like to loosen up, but it can be leaking at mufflers if you still have slip ons. If you have a crossover that is another spot to look.
On an S&S Turning up the accelerator pump will mask a lean intermediate jet. This is why you must dial in intermediate first BEFORE you change the main with pump off. Most people put new pipes on and change the main to next bigger jet because someone told them to do it. Most new pipes only require an intermediate change. It is a pain in the ass process because the bowl has to be removed, but there is no way around it.
 

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Discussion Starter #9
I replaced the exhaust gaskets when I changed to my two into one exhaust. I ordered a jet kit to play with tuning. I recall checking my plugs and they were kinda white. I did check my intake with some wd-40 while it was running.
269021
 

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Discussion Starter #10
Isn’t some decel popping normal? I don’t think I’ve ever had a Harley that didn’t have some decel pop haha. Maybe I’ve never been on a properly tuned Harley ?
From what I've read, if it's a free flowing muffler/exhaust it will always decel pop a little bit. You can minimize it with sealing any intake or exhaust leaks, and good carb jetting.
 

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Discussion Starter #11
Exhaust leak are the main cause for decal pops. The head bolts in the pipes like to loosen up, but it can be leaking at mufflers if you still have slip ons. If you have a crossover that is another spot to look.
On an S&S Turning up the accelerator pump will mask a lean intermediate jet. This is why you must dial in intermediate first BEFORE you change the main with pump off. Most people put new pipes on and change the main to next bigger jet because someone told them to do it. Most new pipes only require an intermediate change. It is a pain in the ass process because the bowl has to be removed, but there is no way around it.
This is what I'm going to tinker with tomorrow after I get my wheel back on. Was doing some test fitting with a mag wheel I got. On a side note anyone know what rotor I need for a rear 9 spoke mag wheel? The belt pulley from spoked wheel fit but not the rotor
 
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