Sportster poor performance

Discussion in 'Engine, Fuel and Exhaust' started by streetrodderbn, May 31, 2013.

  1. streetrodderbn

    streetrodderbn New Member

    Hi! I just picked up a 99 Sportster with @9,000 miles, When I test rode the bike, it took a real long time before the engine warmed up to let it idle/run without the enrichment valve being pulled out, it seems that the engine does not want to take the gas when you twist the throttle. I was told by the previous owner that he had not run the bike in some time, but did have "Stabil" in the gas tank. I rode the bike home and have changed plugs and plan to dump the tank and clean the carb, I removed the air filter in preparation of rebuilding the carb, and I notice I don't have much accelerator pump shot when I twist the throttle. I have the stock carb with a HD stage 1 dynojet kit and foam air filter installed (by the previous owner). I just installed a set of slip on Screamin Eagle II mufflers, and have the factory HD service manual to guide me through the r+r of the carb rebuild, am I on the right track??
  2. Fastlinnie

    Fastlinnie Member

    Yes your on the right track. most of the time the low speed jet will be stoped up
  3. Slo-Ryd

    Slo-Ryd Junior Member Contributor

    The accelerator pump is a rubber diaphram located on the bottom right front of the carb and can easily be changed. You will see a round casting about the size of a quarter with three screws. The diaphram resides under that cover. Be careful not to lose the small check ball or spring when taking it apart A complete rebuild kit isn't too expensive and would be one of the first things I would look into for safe measure along with a good cleaning. A small pin hole in the pump diaphram may be difficult to see at least with my old eyes. I love CV carbs and they are fairly easy to work on and understand. Tons of tuning info on here and other sites. Get yourself some carb cleaner and give a shout back or pm me. I can walk you through the rebuild.
    1 person likes this.
  4. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

    Sounds like a great plan. I am with BigAl on the diaphragm. Get you a rebuild kit and go at it. Let us know how you make out. J&P sells a James kit with all you need.
  5. Iceman24

    Iceman24 Well-Known Member

    Even though Sporty's can be cold-blooded a bit, seems like you've got something amiss in the carb. Definitely take Fastlinnie and BigAl's advice and let us know if it smooths things out...good luck!

    BUBBIE Well-Known Member

    883 or 1200?

    That squirt should be a full stream... Cleaning (for sure) and maybe a larger idle jet MIGHT be needed. Clean first... I always replace the 4 screws holding the float bowl with allen headed 5/8 long screws,don't like the phillips there:(
    Allen's used Not for over tightening (careful). Just used for ease of apart while carb is still on the bike.

    I have a 06 1200 sport R and it dows take a little to warm up so it will respond. I have the jets set for here in Az. at 4400 feet. IT Does get up and go ONCE warmed properly.Never expect a cold motor to last long IF not warmed up to normal running temps. The types that get on their bikes and go WOT off the get go usually are the ones with EARLY problems.

    Use a good Primary-clutch-tranny oil.
    (all 3 share oil in one location,,, the primary)...

    I still use Formula + from HD for the above3, Formula + is wet clutch approved, does good lubing all three( primary chain, clutch, tranny gears.)

    Use a good 20/50 synthetic oil for the engine.

    like BigAl66 says....... Give him a PM and he is a good guy to trust to steer you correctly... Just watching over his shoulder, he usually is hard to follow up on with More Advice.:s

  7. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

    I agree with all the previous said stuff about a good rebuild of the carb a new tank of fuel and when the tank is empty remove the petcock and clean the filter screen and perhaps replace the fuel pipes
    It would also be perhaps prudent to replace the intake manifold gaskets as they can leak and draw air weakening the mixture
    Sounds like a busy weekend along with test riding etc
    When you have the carb apart check the size of the jets although most on this site prefer to run carbs with stock components rather than the dynojet stuff

  8. streetrodderbn

    streetrodderbn New Member

    Thanks! Great info. I'm tearing into the carb today, I'll post my results!:D
  9. streetrodderbn

    streetrodderbn New Member

    After tearing down the carb and dumping the tank, I discovered the Accelerator pump diaphragm was bad. I went to a local shop and bought a new one, put it back together, and it runs AWESOME!!! thanks guys!:D
  10. Fastlinnie

    Fastlinnie Member

    Awesome good job. Thanks for posting you got it fixed