Question about 2000 Harley Davidson FLSTF Fat boy

1 Answer

Idles, but no acceleration

When I start my 2000 Fatboy, it idles, but when I get on the throttle, it seems like no gas is going into the carb and dies. But when I let off on the throttle it will again idle. I have a Mikuni carb.

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  • wd4ity
    wd4ity May 11, 2010

    Which Mikuni card do you have? Is it one of the flat slide carbs or is it the Screamin' Eagle CV type? If it's either type, check the operation of your accelerator pump. With the engine OFF and the air filter off, crank the throttle wide open while looking onto the carb. You should see a squirt of fuel shoot into the carb each time you work the throttle. If not, your accelerator pump is not working for some reason. If the carb is a CV carb, remove the air filter and start the engine. When you rev engine, the slide should move up and down rapidly. If it still won't rev up, I would suspect that you have a stopped up main jet. You'll probably have to remove the float bowl to clean this out. Good Luck Steve


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  • Harley Davidson Master
  • 40,013 Answers

Hi 1finehog, if you have a carburator the usual suspects are:
1. Damaged or restricted fuel tank venting system (gas cap).
2. Inlet system air leak.
3. Vacuum piston malfunction.
4. Accelerator pump leaking or no output.
5. Plugged bowl vent.
6. Fuel level (float chamber) too low.
7. Restriccted fuel supply passages.
8. Plugged jets or passages.
9. Worn or damaged needle or needle jet.
10. Enrichner valve not seated or leaking.
Good luck

Posted on Jun 18, 2015

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Posted on Jan 02, 2017

  • 3567 Answers

SOURCE: Backfire out of carb!

Remove and clean the carbs. Clean the air filter and install new stock plugs. Re-mount the carbs and then balance and sync them. Now would also be a good time for a compression check. Valves and rings do give problems sometimes but these problems show up first as a lack of power. Since you didn't report a power problem I doubt if valves are the problem.

Posted on Mar 26, 2009

  • 3567 Answers

SOURCE: i own a 2000 harley sportster 1200 and its dying

Clean the carbs. Sounds like the main jet is plugged up.

Posted on Mar 30, 2009

  • 3567 Answers

SOURCE: XR 70. Idles fine. Won't throttle up just dies. Changed Plug, gas, cleaned carb...what am I missing

ALWAYS have a fire extinguisher at hand when working on carburetors.
Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).

Drain the carburetor. There should be a screw on the lower side of the carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. Install a new stock NGK spark plug and try to start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine.

Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the idle screw and the air screw on the outside throat of the
carb and spray into the screw holes as well.
Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two adjusters down. Only screw these in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward. Before putting the slides back in the throat of the carbs, move the clip on the jet needle one notch lower. Put the rest of the
carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. This process should get you back on the road.

Please rate this solution. Thanks!

Posted on May 08, 2009

  • 4336 Answers

SOURCE: 2006 Harley ruff idle and hesitation acceleration

This sounds lean, from your description. The best way to set it is with an exhaust analyzer... Be sure to look for intake leaks also.

Posted on Sep 07, 2009

  • 4565 Answers

SOURCE: High Idle On Start-up.

Most fuel injected motorcycles do start up in a "fast idle" mode. Although I don't know much about fuel injection on Harleys (H-D will not tell you much about it unles you are one of their technicians), I don't think the system is equipped with an engine temp sensor. Since the crank case sensor get it's pulses from pockets cut into the outer edge of the left side flywheel half, the sensor will have oil on it.

Posted on Sep 24, 2009

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