2003 sportster 883, it’s my buddies bike he bought for next to nothing and had me get it running. Getting it running was a bit of a fight figuring out what wires went to what without a diagram but turned out to be the BAS was shot. Finally got it running, like crap but still running. Pulled the carb cleaned and inspected everything. Completely stock bike and jets. Got it back together and still ran like poo so I pulled the plugs to see if it was rich lean etc. turned out whoever changed the plugs last apparently dropped one and the strap bent over and touched the electrode. No worries it doesn’t look like a piston touched it by any means the strap is smooth and the piston doesn’t have any witness marks. So it finally idles great and runs pretty good but it’s still doing a weird thing where when you go from just about any throttle position to WOT it seems like it just dies. Let off the throttle and goose it a couple times and she’ll come back around. It also backed fired through the carb and actually blew it off the manifold (no filter on at the moment). My question is are these related? It seems like it’s over fueling at WOT but the backfires says it’s running lean. Any ideas? Thanks!

 

Verify the timing, verify accelerator pump is squirting.

 

Timing has the original ICM untouched I drilled the rivets out while figuring out the no run problem. The accelerator pump is definitely working I changed the angle of it spray more at the throat of the carb rather than the wall. Something else I forgot to mention is that it seems to be misting fuel back out of the carb on my leg at times as well.

 

How do you know the timing is correct? Did you physically verify the timing? The fuel is called fuel standoff and happens at times - you are not running an air filter so it will be very noticeable. Also, if you installed the main needle jet upside down, it will have those symptoms. That is the silver piece with a collar that the main needle (on the slide) drops into.

 

I didn’t physically verify the time was correct I just went off the fact that it had never been messed with before I opened it up and the screws you unbolt to adjust the timing have no sign of ever being touched and the nose cone has no witness marks of it having loosened over time and getting out of time that way. I have the small collared jet that the emulsion tube pushes into the throat with conical side in the throat. And the side that matches the OD of emulsion tube facing the bowl.

 

"dished" side faces up toward the needle - sounds like you have it correct.

Make sure the diaphragm is not torn/leaking

Did you replace the plugs and check the wires and all the basics?

 

I did. That’s how I found the plug with the strap bent over and touching the electrode. I ohm checked the plug wires and they came out fine. I’m wondering now if maybe the intake gaskets are leaking. I tried both MAP and Propane gas but it didn’t idle up. I also stuck the nose of the torch into the carb to see if it would idle differently or stumble to use it as a base line so I knew what I was listening for, but it didn’t change then either. I did get the tiniest of a stumble when I hosed down the back of one of the intake flanges with flammable brake clean. But I’m not certain it didn’t just get sucked in through the intake normally. I’m going to chase that rabbit tomorrow I believe. Maybe it was lean bogging when I thought it was over fueling. I’m typically pretty good at working through these things but I’m really stumped. On one hand it’s extremely aggravating and on the other it’s enjoyable because I haven’t seen this before. I wonder if I could figure out a way bring the entire induction system under a vacuum and see if it held or lost pressure. I’m not sure if both the intake valves are ever closed at the same time or not. Hmmm.. or I could smoke it and if it comes out of a breather port I’ll know it’s just blowing through an intake valve and into the case and back out.

 

I'm thinking you should see how it runs with the air filter on before you start altering things .

 

Yes! Although this is slightly off issue, back in the 60's my buddy got a new Pontiac GTO with "3 deuces". The first thing he did was "take off the breathers" because that's just what you did back then when you were a kid who didn't know any better. The car ran great and the carbs sounded great. Three of us went to a movie on a fall evening and the temperature dropped below freezing while we were in the theater. When he started the car, the engine backfired and caught on fire. Not knowing any better, he didn't think to turn the ignition key off and stop the fuel pump even though the engine had died. There was a lot of damage to the car because of taking the air filters off and the temperature dropping.

 

When you dyno test a carbureted bike, you remove the air cleaner and do a more air/less air test and see what happens. If they make more power, they were rich and if less, they were lean. Fuel standoff will go back into the carb, so having the air cleaner on would help if lean.

OP is saying the bike is super rich so going with that info. Feathering to achieve RPM makes me think lean.

If the bike is way too lean, it could be an issue without it, but it should also display other signs of being too lean (runs better warm, popping, etc.)

In the case of the car mentioned above, air cleaners are also flame arrestors.

From the OPs comment on using smoke to check intake, I am getting the impression the OP may be an auto tech, because checking intake leaks on HDs is not that complicated and certainly not worth the effort. I also am not 100% he is sure if it is rich or lean at this point.