Help! EVO CV Lean Question..

Discussion in 'Engine, Fuel and Exhaust' started by _whitey_, Mar 16, 2012.

  1. _whitey_

    _whitey_ New Member

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    Recently acquired a 1994 FXDWG with mileage at 20,000ish, and as far as I know it's completely stock.

    While tracking down an annoying rattling noise, I pulled the front exhaust pipe. Looking in the head, I can see that the valve is white..and by white, I mean "frosty" white. I'm assuming that this is from running at an extremely lean condition. I checked and plug/cover for the carb mixture screw was missing, so at some point, someone had been fiddling around with it. I replaced the spark plugs on bringing the bike home and 700 miles later, they appear to be burning properly..light greyish..no blistering or white flakes.
    The white valves really came as a total shock to me, because this bike runs 100%....starts..idles..excels..cruises..all EXCELLENT. However I did notice on two or three occasions, on deceleration, there was a single "pop" from the carb...this was in the 700 miles I've put on it. At the time, was thinking the pops were from the very cold air I was riding in.
    Man, I hate the thought of monkeying around with something that runs so strong, but the white valve does have me concerned.

    So, my question for the more knowledgeable.. should I crank out the mixture screw slightly..or maybe a larger jet?

    Any info would be greatly appreciated..
    Thanks!

    Oh, and the rattling noise turned out to be a broken muffler bolt..replaced it ,and what a much more pleasant ride experience!
     
  2. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The mixture screw only really has an effect at idle although the adjustment of it will let you know if the slow jet is of sufficient size
    it may be worth raising the main jet needle by placing a few washers under the seat of the needle this will bring the taper on sooner and richen the mixture a wee bit
    if you go to the self help section you will find articles on carb tuning that are worth reading and understanding
    and if you have any questions please come back and ask and we will try to increase your knowledge of carb tuning

    Brian
     
  3. Jack Klarich

    Jack Klarich Expert Member

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    Welcome to The Forum Fuel and Carb Related Issues - Harley Davidson Community Have a look here, you will find most all of your answers for C V carbs here
     
  4. _whitey_

    _whitey_ New Member

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    Thank you.

    The site proved invaluable with my transmission and primary seals replacement project. Couldn't have done it without the research I did here first.

    Stopped into Ace and picked up a few #4 brass washers, and going to give that a try....Reading up on the CV carb now.

    Thanks for the suggestion..
     
  5. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    I love the Keihin CV carb. Simple but effective, and very tunable. Do you know what jets are in it now? And what modifications have been made to the engine, particularly the A/C and the exhaust.

    TQ
     
  6. Jack Klarich

    Jack Klarich Expert Member

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  7. _whitey_

    _whitey_ New Member

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    I plan on removing the carb this weekend, so I'll soon discover if someone has changed jets etc.

    Had it not been for the rattling noise, I would have never known there was an even an issue...seriously, it runs that beautifully.
    Hopefully, if will remain that way AFTER I start tinkering with it.

    VOES SWITCH?...wow, so much to learn..:D:
     
  8. Breeze3at

    Breeze3at Well-Known Member

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    Hi Whitey; Just thought I'd add a couple of cautions for removing the top of the carb. Be super careful taking the cover off of the diaphragm, and or getting the dia. unstuck from the carb. body. The rubber can rip easily. Also, you may notice a brass ferrule fall out. It goes in the rear hole (I think).