Help Posible fuel problems

markncarj1 · #1 30th May 2012

Ok when i went on a ride on thursday i fueled up and drove 100 miles then went home and parked it for the holiday weekend. Now my bike ran fine for the most part that i could tell after the fuelup but it was extremely windy. I did notice with a heavy head wind in 5th gear i was pretty heavy on the throttle at 60mph. I have a 2002 883c with a thunder header and k an n filter. when i parked it till tuesday, i came home and went for a short ride. got going down the road and it felt a little sluggish so i put it on reserve and didnt make much of a diffrence. Got gas and seemed ok but after it would warm up, when i come to a stop it had a delay when i blip the throttle. when i really get on it it doesnt seem to quite have the power. Only when you first start it up it runs great but then slowly gets worse. today i rode it and then i sat and let it idle for 30 seconds and bliped the throttle and the delay gets worse till you get into the mid circuit. i did a bunch of blips in a row and it just killed it. tried the mixture screw out a turn and in a turn and it doesnt seem to get rid of the delay. i pulled the carb and cleaned it and made no diffrence. Im thinking vapor lock? cause in the morning in colder temps it runs great. I am at 4300 feet too. Prior to this the bike ran great. i have since ran 2 tanks of fuel through the bike as well from diffrent stations and 92 everytime.

sportsterdoc · #2 30th May 2012

Turn the idle mixture screw in until it seats, then backout 2.5 turns.
That will probably not make a difference, but at least you will know what you have there.
Remove the ham can
When you blimp the throttle, after a moment of delay, does the CV diaphragm lift the slide/needle?
If not, the diaphragm is likely at fault.
One time I put a CV carb back together and did not properly seat the diaphragm. Not much response was my first clue!
There could be many other reasons, but this is where I would start.

markncarj1 · #3 30th May 2012

the diaphram works as designed. hasnt been touched. the engine temp is at normal as well. i set the idle mixture at 3 and 2.5 and 2 and all the same result

sportsterdoc · #4 31st May 2012

Diaphragm lifts slide and needle fully, if throttle is held open?
Accelerator pump squirts?
Maybe not fuel?
Have you checked for a strong spark?
Your ignition module is in the nose cone and could have gotten hot when you were in the headwind. Remove the cover (drill out rivets and tap for screws [8/32?] to reinstall)
Blow a fan over the module and see if it makes difference, even for a short time.

markncarj1 · #5 31st May 2012

slide lifts and accelerator pump squirts. hmmm, ign module, seems like it could be it. I will check it tonite.

markncarj1 · #6 31st May 2012

also after blipping the throttle and killing it i pulled the plug and it was dry so if spark was an issue wouldnt ther be fuel on the plugs?

markncarj1 · #7 31st May 2012

I have a video if there is a way to post it here

sportsterdoc · #8 31st May 2012

Dry plugs...
How good is the flow through the petcock?
Vacuum line intact to the petcock?
Petcock vacuum diaphragm OK?

markncarj1 · #9 31st May 2012

k cleaned the petcock and replaced a bad hose. so took it out for a nite ride and brought it back and i blipped the throttle a few times and noticed black smoke so it seems that the accellerator pump is pushing too much fuel and it is flooding it. must be the temp change and humidity change. i just dont get it that in a few days it could do this. top end is much better that i fixed the Vacuume hose.

sportsterdoc · #10 31st May 2012

Glad for the improvement
How black? It could be the need for new plugs, it could be retarded timing and not enough burn time or it could be the accelerator pump or something else with the carb.
I would start with new plugs. Champions are cheap and available from any auto parts