help sportster runs for a week then dies

[groggg]

2003 883 sportster with a ness air cleaner and thunder header. I've rode this bike rain or shine almost everyday for the past two years and its never gave me problems till a couple months ago. at first it would start up just fine in the morning, ride to work, then sit for 8 hours, try to leave work and nothing but blubbery backfire. about 10-30 mins of trying to start it it finally starts and i get home.

took it to a shop that got it running by "putting a jet kit and accelerated pump kit" and a week later went right back to backfire not starting, the guys at the shop said theres nothing more they could do and thats the way the bike just runs. i heard sportsters could run a little funny or leaky but for some "mechanic" to tell me that my not running bike is all better?

i pulled the dry soot covered plugs and pulled the #50 slow jet and replaced it with a #45 (#50 looked smaller than the #45? maybe a jet for a different carb?) and tuned air fuel screw to what i think sounded like it used to, bike ran way more responsive but started popping through the carb. ran the bike for two days and again no start but loud backfire from exhaust, 3 more button pushes and bike started up, got home looked at the plugs and their white with white chalky shit on the outer electrode and a little bit of black soot on the edge of the threaded base.

I'm waiting on a cv performance order with a replacement needle and a #46 jet but now I'm thinking it may not be a fuel problem, its driving me crazy. I've heard the get a better bike solution but anybody got some in put or anything i could try?

[seaking]

Don't ever go to that shop again. Sounds like they just throw money at it til it's fixed. No. 45 is stock CV for sportsters, 48 big twin stock, just go with the 45 if you still have it. The 46 is probably ok for now.
I'd bet it's the stock ignition. Mine had the same symptoms, it'd run OK for a week then take a shit, and would only backfire after that. I changed almost every component when I found a cheap replacement, and the ign. was the problem. I even had decent spark, it seemed off time and wasn't blue though.
The ultima kit comes with a dual fire coil as well, there's no real advantage to it but it'll allow you other options for programming--I just bought the ign. and I'm stuck with that stock coil.

It's easy to install, you might be able to get a new OEM connector so you don't have to wire it in with butt connections like I did--look up how to heat-shrink wire, that works fine for me.

[kombi66]

if it were mine i would perform some leak down test on it and also look for intake leaks

[seaking]

Eh I tried that too and it was pointless IMO. That was the first thing the mechanic I usually use suggested, they do carry those in carb rebuild kits though it's good if you just want to hit it for maintenance. You'd check that with starter fluid anyway. If you want to make a leak-down tester, someone suggested bashing all the porcelain off a spark plug and welding an air hose fitting to it. Compression is fine, especially on an Evo--it's not going to need a major overhaul unless it smokes or pukes oil.

[kombi66]

didnt notice it was an evo...oops thats too complicated for my simple mind to wrap around lol

[Enzoline]

Stock with stock pipes is 42-170
Air-fuel 2-turns out

[groggg]

i was thinkin ignition but wouldnt it be hard to start when its hot? or at operating temp?

[BrokenSprocketGarage]

Don't ever go to that shop again. Sounds like they just throw money at it til it's fixed. No. 45 is stock CV for sportsters, 48 big twin stock, just go with the 45 if you still have it. The 46 is probably ok for now.
I'd bet it's the stock ignition. Mine had the same symptoms, it'd run OK for a week then take a shit, and would only backfire after that. I changed almost every component when I found a cheap replacement, and the ign. was the problem. I even had decent spark, it seemed off time and wasn't blue though.
The ultima kit comes with a dual fire coil as well, there's no real advantage to it but it'll allow you other options for programming--I just bought the ign. and I'm stuck with that stock coil.

It's easy to install, you might be able to get a new OEM connector so you don't have to wire it in with butt connections like I did--look up how to heat-shrink wire, that works fine for me.

These stated jet sizes are all wrong. Stock slow speed jet on an 883/1200 is 42. EVO BT is also 42, TC88 is 45.
Anyway, probably not fuel related. Likely to be ignition or battery related. Check battery cable condition, seen many of this vintage with bad crimps and the wire pulls right out of the terminal. Check timing, and verify VOES operation with advance timing light and that it opens and closes at specified(in your FSM) vacuum. Check for intake leak. Verify enrichener plunger and circuit/passages are clear.

[groggg]

These stated jet sizes are all wrong. Stock slow speed jet on an 883/1200 is 42. EVO BT is also 42, TC88 is 45.
Anyway, probably not fuel related. Likely to be ignition or battery related. Check battery cable condition, seen many of this vintage with bad crimps and the wire pulls right out of the terminal. Check timing, and verify VOES operation with advance timing light and that it opens and closes at specified(in your FSM) vacuum. Check for intake leak. Verify enrichener plunger and circuit/passages are clear.

ok so i guess the 46/170 maybe 175 jets would be cool for the ness air cleaner and t header? im still playing around with the jets trying to get it back to how it was. i figure i should get a new battery anyway since its been a couple years. hopefully its just a busted battery cable. might be a while before i check timing, but ill read through the book and figure it out. thanks guys i appreciate the help