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I have an '02 Dyna superglide FXDX. I've been trying to research re-jetting my bike but cannot find a solid answer.
I have put Arlen ness high flow air cleaner and a thunderheader on it with a stock carb. The bike is coughing quite a bit when going down the road. I want to get it jetted correctly for riding this weekend. What would be the correct size jet to go to? And will I only need to swap the main jet?
My first Harley was a '90 FXR 80" EVO running a T-header with S&S Teardrop A/C. I used a #48 slow jet and a #180 main jet, and I also raised the needle a notch or two to fatten up the mixture as the CV carb opened up. Motor ran smooth, plugs ran clean. Your 88" motor may need slightly bigger jets, but the jet #s mentioned would be a good starting point.
One other thing you might want to check are the intake manifold-to-head gaskets - if they are leaking your motor will run lean and could be the cause of the "coughing" you're experiencing. Hope you get it worked out.
03' FXDX with the T-Header and about the same air cleaner as you. When I ran the CV carb I used 46/180 with one or two washers under the needle and it ran good. I tried the sportster needle and it ran too rich down low, 48 jet was rich all around. I'm at sea level so take that into account.
A carb... the way an HD is supposed to be, back when you needed a hardware store and not a software engineer to tune. I'd rather a carb than FI any day
The best method will be the trial and error/seat of the pants dyno to find your sweet spot. If you've not removed the plug to access the air mixture screw be certain to do that first. The Twin Cam 88's I've done all seem to end up in the 2 to 2 1/8 turns out from light seat.
Since you're going to be removing the cheap float bowl and carb cover screws stop by the hardware store and pick up some nice allen stainless hardware, makes future work much easier and they look nicer.
While you're at the hardware store buy several #4 brass washers; NOT M4 washers, the M4 washers will get hung up in the slide and bind the needle. The idea is to use the #4 brass washers to shim the needle as O-Town D and 748*2Risk have already posted about. I've found 2 washers have given me the best results.
The main jet tends to be pretty close but you may need to change it out depending on your specific setup. The pilot jet is the bigger issue, pick up a #46 and #48. On some setups I've found the #48 would be slightly too rich, again, it's all about your specific setup.
The last CV carb I did on my '03 Wide Glide with free flowing A/C and V&H Big Shots Staggered ended up with the air mixture screw at 2 turns out from light seat, stock main jet, #48 pilot jet, and 2 #4 brass washers on the needle. Thing was a beastie
Do a Google search for 'Joe Minton CV carb tuning' and read his articles; he's the master of tuning the CV carb
I got a 01 lowrider. Since day one. It's had a hiccup with acceleration right at the beginning but after it hiccups it runs like bad out hell but really bugging me in curve or performance times it bulaa up.. then full power never skips a beat then. Even every speed once you let out that gas get back in it hiccups one time then full power. Should I try new jets or just put whole new carb on it. Been cleaned twice already
I find it a bit baffling that nobody is stressing the important ART of reading your spark plugs. Your spark plugs will tell you exactly what you need to know about your jetting before you start twisting bolts and spraying carb cleaner everywhere looking for leaks.
A spark plug and its colorations on different parts of the plug from the strap, to the porcelain, to your threads will tell you exactly whats going on. Each area of the plugs coloring will represent throttle positions. From idle. To full throttle. Plus it can also make you aware of any internal engine problems from detonation and so on.
Keep carb tuning an art and science!!! Fuel injection is BS. Before FI and power commanders. All we had was carbs. And we had to learn every aspect of tuning a bike perfectly without a computer.
As far as jetting recommendations, EVERY ENGINE IS DIFFERENT! Even with identical parts. Ive seen big jetting differences in identically setup bikes. Thats the truth and it is what it is.
This is why the art of reading your spark plugs on carbd bike is the utmost of importance.
My first Harley was a '90 FXR 80" EVO running a T-header with S&S Teardrop A/C. I used a #48 slow jet and a #180 main jet, and I also raised the needle a notch or two to fatten up the mixture as the CV carb opened up. Motor ran smooth, plugs ran clean. Your 88" motor may need slightly bigger jets, but the jet #s mentioned would be a good starting point.
One other thing you might want to check are the intake manifold-to-head gaskets - if they are leaking your motor will run lean and could be the cause of the "coughing" you're experiencing. Hope you get it worked out.
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Carb jetting question
