Fuel System Advice

Discussion in 'Touring Models' started by CalgaryBikeBum, Sep 8, 2009.

  1. CalgaryBikeBum

    CalgaryBikeBum Active Member

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    Okay. My bike is all rebuilt now but still not happy with the stock carb? 2000 Roadking with the CV Keihn carb. So now i'm trying to decide whether to buy an new carb with more pizzaz or go for the after market fuel injection system. Difference in price is probably about 1000 bucks but I do kind of believe in fuel injection. Your opinions? If a carb what carb??? Not that familiar with my choices. Thanks :D
     
  2. kemo

    kemo R.I.P

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    I would stay with your stock carb and find someone that will work with you and the carb. That stock carb is highly under rated and is very capable of performing for you and is reliable without having fuel pump and relay and injector and theottle body issues.
     
  3. CalgaryBikeBum

    CalgaryBikeBum Active Member

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    Well I did follow Glider's advice and it was running pretty good up till recently? I would be rolling on it and around 3800 rpm if I stayed there it would suddenly drop out and sputter like it was out of gas? I would back off and if I waited a bit it would come back and all was fine again? Thought perhaps it was the vented gas cap crapping out but more apt to think its the diaphram or perhaps something getting in to one of the orifices? Wanted fuel injection and i'm comfortable doing it but still thinking carb is ok too if I can set it up right. I am going to check diaphram for a pin hole when I pull the carb this week. Thanks for advice
     
  4. glider

    glider Veteran Member

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    Kemo is right. Stick with the stock CV carb. After market carbs and FI isn't going to give you much and the investment would be large for a very small return.

    It sounds like you have a fuel problem from something in the tank rather than a carb problem in itself. If you feel what you describe as "falling out" on you , it may be to your advantage to remove the tank and clean it out flushed with some fresh gas and clean out the carb too. You even made mention that it ran good before but not now. This indicates something possibly in the fuel system.
     
  5. kemo

    kemo R.I.P

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    Have you pulled the fuel petcock and checked the fuel filter screen. You might have some crud plugging the filter screen. Maybe even a kinked fuel hose or possibly a vac leak in the vac line that goes to the petcock.
     
  6. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The first winter i had my softail i had a lot of problems with the bike running a lot of backfiring when cold and would cut out when i slowed down for the first town i came to after setting off
    rebuilt carb 3 times changed the diaphragm adjusted the jet sizes problem kept reoccurring did some research and found the problem to be carb icing this was partially due to the restriction in the air box and the flow of air through the throat of the carb
    Managed to fix the problem by fitting a mikuni hsr42 and a mikuni air filter and i have never looked back the stock cv carb seems to work fine on the sportster all year round but does give some trouble on the Dyna so it may get the mikuni treatment as it does do a lot of backfiring and bad running in wet weather normally at 1/4 to 1/2 throttle but I'm still working on that one and all we seem to get in summer here is rain its been a bit of a pest the last couple of months

    Brian
     
  7. Breeze3at

    Breeze3at Well-Known Member

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    The cv is a good carb. The basic mods we did on them were to drill out the air hole in the slide to 1/8", this allows vac. to pull it up quicker. The other was to change the slide needle out with the part # for a 1988 1200cc XLH, then just some fiddling with needle positions and main and pilot jets should give you decent performance. I eventually went with a 42mm Mikuni, just because I had to have it, I never regretted it.
     
  8. CalgaryBikeBum

    CalgaryBikeBum Active Member

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    Well I did pull the petcock and clean it but it was brand new ( there wasnt much that I did redo or replace) and I had washed the tank out and then sealed with that tank sealer? Checked that all openings were clean after I had painted it? It only seems to happen when you are really rolling at higher rpm for extended time?? I thought perhaps float was set too low and bike engine was gaining on it? Now that I have my Baker six speed I don';t need to run higher rpm to keep up? I should mention that it was upgraded to a 95 Ci too? Of course as I said it did run well but I also took it easy on the rpm's because I was breaking it in? New fuel lines, new stainless crossover? I did hear a hiss a few times when I opened the gas cap so that's why I thought it was sucking a vacuum? Hose to vacuum pot on petcock is fine? Any other thoughts?
     
  9. glider

    glider Veteran Member

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    Lots do these mods but drilling the slide can have adverse effects in cold temps if the throttle is opened too fast. It will bog down from a lean condition.
    I also don't like to drill the slide and the sporty needle #27094-88 was from a carb that didn't have an accelerator pump and is a bit too rich IMO for a carb that does have one. Lifting the needle with 2 - #4 washers is the better way to go by bringing in the fuel circuits a bit earlier rather than over doing the mixture.
     
  10. Breeze3at

    Breeze3at Well-Known Member

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    Being from the south, I have no experience with cold temps. All Keihn carbs from '76 on had accelerator pumps. They wern't CV until '90.:)