Back fires/spits back thru carb after it warms up it spits back at acceleration sitting still or starting off. it has had autolite plugs put in. the pump diaphragm is working. if you look into the carb, it looks black and the inside of the filter does too.

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Hi David, HD 6R12 gapped at .040" are the correct spark plugs to use in you 2005 XL 883 and the usual suspects are:
1. Spark plugs in bad condition or partially fouled.
2. Spark plug cables in bad condition or leaking.
3. Spark plug gap to close or to wide.
4. Faulty ignition coil, module and or sensor.
5. Battery nearly discharged.
6. Damaged wire or loose connections at battery terminals especially the ground cable at BOTH ends, ignition coil, or plug between ignition sensor and module.
7. Intermittent short circuit due to damaged wire insulation.
8. Water or dirt in fuel system, carburetor or filter.
9. Fuel tank vent system plugged or carburetor vent line closed off.
10. Carburetor controls misadjusted.
11. Damaged carburetor or intake seals.
12. Loose or dirty ignition module connector at crankcase.
13. Faulty MAP, CKP, and or CMP sensors.
14. Incorrect valve timing.
15. Weak or broken valve springs.
16. Damage intake or exhaust valve.
For a prime suspect please visit website below and good luck:
Harley Davidson Sportster error codes and how to access them
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