Hey everyone. So I have recently done a stage 1 upgrade on my bike. I have a 2000 fxdx. I put on a thunderheader exhaust and an Arlen ness stage 1 big sucker. I'm still running the stock carb and don't really intend to change that quite yet. My question is though, how much of a jump in jet sizes should I do? Anyone running the same set up that has done this before?

 

What altitude are you at? A 46 pilot & the stock main jets will get you very close. I've always had good luck with the '88/'89 XL needle, though some don't care for it.

Make sure to drill/pull the cap thingy to uncover the idle mixture screw, get idle speed & mixture right 'n those jets will get you 90% of the way there.

I'm at 700' & run a 46 pilot, 2 shims under the Sportster needle & stock 190 main & the bike runs perfectly (88", Cycle Shack slip-ons, hi-flow a/c & mild cams). I shimmed the needle to cure an occasional low rpm sneeze. Dunno what kinda mileage I'll get with the addition of new cams, but I've averaged right at 48mph for the last couple of years.

 

Unless your planning on doing serious work to the bike the stock carb should be fine. The key piece will be drilling out the mixture screw cap as previously mentioned. Depending on how far in/out you end up turning that screw will tell you where you need to go with the pilot jet. Will probably end up with a 46 or 48 though.

 

I am with Carl '69 on his suggestions and may I add, the p/n number for the Sportster needle is 27094-88 and the washers are #4 brass washers, if you use the stock needle. I got the washers at ACE Hardware.

 

Might change the "emulsion tube" as well. Mine came in the kit from dynojet.

 

Wasn't sure if those were a "thing" any more. I used a Yost Power Tube in my old '94 Sportster. Bike was seriously quick, instant throttle response & averaged over 52mpg at 70+ mph to & from Sturgis in '96. Can't attribute all that to the emulsion tube, obviously, but it certainly didn't hurt anything.

CV40s are pretty simple carbs & easy to tune.