Slow Sportster

My '02 Sportster XL883C wont do 80 MPH. What's up with that? I put drag pipes on it. (I know; not the best choice...will change, soon) I also installed the CVP tuner's kit using the recommended jetting. Still, no help. So, I yanked the stock air cleaner and installed the Kuryakyn Hypercharger with a K&N filter. I used the CVP recommended jetting for "Stage 1," this time. No change...at ALL. The bike comes out of the chute fairly quickly and pulls fairly well through accelleration all the way up to 65 MPH in 5th gear. Cruising is no issue. However, at 65, when I roll the throttle back, it struggles to get to 70 and it just won't go any higher. There's still 3/8 to 1/4 of my throttle left but it's completely dead space. This is my daily commuter so it doesn't need to be a demon but it would be nice if it could pass cars at 45 MPH without dropping a gear. On the bright side, it has been getting 51 MPG, consistently. A couple of final notes: The plugs are slightly powder-white and the previous owner mentioned having installed "bolt-in cams" but he didnt give me the specs on WHICH cams he installed. Any suggestions appreciated.

Your engine is running lean and hot, I would go with a bigger jet.

I'm 210. I have looking at the exploded view of the carb and I think I'm missing a part on the main jet tube. I obviously have the main jet on the one end of the tube. However, the exploded view shows a "needle jet" on the other end. I do not have that part. Could this be causing the main jet to fail to actuate?

Oh, I ordered the part immediately upon realizing the problem. Funny...when I bought the bike, it had stock pipes on it that were COMPLETELY blue from the heads to the tips. I attributed it to the cams that the previous owner told me that he had installed and I just bought new pipes and the CVP tuner kit figuring that would take care of the problem. When it didn't...If the needle jet had been on the emulsion tube that I removed, I certainly would have moved it over to the new emulsion tube. It definitely was not and that explains the blue pipes and overall crappy performance. I'm super stoked to get the new jet installed and finally realize the benefit of the new pipes, jets and air cleaner. I'm guessing that I'll have a pretty good running bike...finally. Thanks for the pointers, guys.

So, I just got my bike back together. New carb/intake gasket, plugs, fuel valve and, of course, needle jet. The only change is that, now, at 3/4 throttle or more, the engine sputters like its choking to death. No acceleration past that point. Just rapid sputtering. Now, what...?

Did that last night. Took the 175 out and put in the 170.
No change.
Then, I removed the Kuryakyn hyper charger and threw the stock AC back on.
Still no change.
Getting very frustrated but very efficient at tear-down / reassembly...

Is it possible that the slide diaphragm has a pinhole or burn in it? I know my 1200 ran lean enough to backfire into the carb and now has burns on the rubber of the diaphragm. Still awaiting CV parts, but I bought a new slide from local Harley dealer. I would think if your plugs are the right heat range and gap, you have inspected/repaired and intake or exhaust leaks, and set up carb with proper jetting/ float level for your application you should be good to go. No sediment in gas tank could have partially blocked petcock?