950 Trouble

Discussion in 'Dakar champion (950/990)' started by motozilla, May 10, 2004.

  1. motozilla

    motozilla Long timer

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    Okay.....disconnected the EPC. did the Sommers air box mod, added Remus slip ons and did the carb jet mod. 3rd slot from top, 4 turns out on the pilot. Runs like shit!!!! Now what???? Won't spin up freely under load. (Seems fat) Pops badly on off throtle decel and even between shifts. (seems lean) This sucks!!! Any help would be apreciated. I'm in PHX at abut 1100 feet of elevation.
    #1
  2. Renegade6

    Renegade6 Been here awhile

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    1) Make sure the caps on top of the carbs (that the EPC used to be connected to) are completely sealed otherwise you can't build a vacum that will raise the slides when the idle circuit shuts off.

    2) Also, make sure that the carb vents lines aren't kinked, as they exit the airbox.

    Sounds more like #1.
    #2
  3. motozilla

    motozilla Long timer

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    OOPS! I vented those. That makes perfect sense too because that was the feeling as I pulled on the throttle. Still too lean on the pilot though even 4 turns out. I guess I'l come two more turns out and see if it helps.
    #3
  4. Renazco

    Renazco Formerly AKA Boejangles

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    Might have to drill out for jetting, I believe "Factory racing" might have put a kit together already for this, worth a try.
    #4
  5. markjenn

    markjenn Long timer

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    Hate to be a nay-sayer, but what problem are you trying to fix? You can really hack up your bike if you start just making wholesale changes based on "hot mods" you pick up on the net. I'd try and get most stuff back to stock and then go from there, making small incremental changes one-by-one. A dyno is the preferred way to do this, but you can get by with the seat of your pants.

    - Mark
    #5
  6. motozilla

    motozilla Long timer

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    I agree and I thought that was what I was doing. First I installed the slip-ons. After that it popped on closed throttle decel. I changed the needle position and fed in 1.5 turns more fuel on the pilot jet. I also opened up the airbox and elimintaed the EPC. I think that's where I went wrong. I vented the EPC carb connection instead of blocking it off. So now it act as though it's on all the time preventing proper vaccum to build in the carb diaphram during acceleration. I'll fix that but I'm still stymied on the decel popping. More pilot adjustment I think...????
    #6
  7. Renazco

    Renazco Formerly AKA Boejangles

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    Might have to bore those pilots, very tricky! I would call Gato88 he's got that thing dialed in on the pilot jet area.
    #7
  8. AZcacti

    AZcacti Dope on a Rope

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    Good luck Paul. I hope you get your tubes and screws all dialed.

    BTW, It's too FREECKEN hot for bicycles !

    Small world isn't. :lol3
    #8
  9. Renegade6

    Renegade6 Been here awhile

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    I think the a lot of the deceleration popping comes from the Secondary Air System, it pumps fresh air into the exhaust. Due to the fact that you have removed your cats, you can probably disable that as well.
    #9
  10. motozilla

    motozilla Long timer

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    That hill we just came up sucks!!! That beeeotch is 10 miles long. I saw you go by and I knew it had to be you so I hustled up the the light. We were just out for a "quick" 90 miles and yes it was hot! I went through 6 bottles of water is 5 hours. :1drink
    #10
  11. motozilla

    motozilla Long timer

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    Where does the SAS pump air back into the exhaust???? I though it pumped it into the airbox.
    #11
  12. KTMax

    KTMax Ninth of the Nazgul

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    I think the carb tops are the main suspect here. One or both the holes where the hoses used to be must be open or leaking.

    Is the choke still working correctly BTW? Maybe with the removal and installation of the carbs something went wrong there.

    Popping on a closed throttle should be there but not excessive. With stock cans my bike popped and with Akra's it still does. It has been setup perfectly at 4.2% CO level. It must pop a little. With more open silencers like Akra's or Remus cans you'll hear it a bit more. By the time you 'dialed out' the popping the idle circuits are way too rich for sure.

    I think you should wait with mess'n things up further by drilling pilot jets etc. There is really no need to do this. :nono
    #12
  13. Renegade6

    Renegade6 Been here awhile

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    #13
  14. motozilla

    motozilla Long timer

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    #14
  15. Renegade6

    Renegade6 Been here awhile

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    If you want an idea of what the block off plate would look like, look at the front page of your engine parts manual. On the right cylinder you can see the connection in the center. Probably could just make a plate out of flat alumimum.
    #15
  16. Doug Matson

    Doug Matson Long timer Supporter

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    The SLS valve takes air out of the air box (topside) and it goes through a reed valve on the side of the head into the exhaust port to mix clean air with the exhaust to clean up the emissions. It will pop more if it is left on, if you have stock cans on leave it on. If you run aftermarket cans then you could take the SLS off.
    #16
  17. gato88

    gato88 Adventurer

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    block off top of carb ,abs black 8mm hole on right side of carbs ,both,
    maybe need to clean plugs,3 and half turns on pilot should be close,
    I have no popping on decel,I guess call sommer
    I'm sure this should be left to experts.............. :nod
    #17
  18. merlin

    merlin Been here awhile

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    "Air Screws" In cuts air off....(richer) out opens air up (leaner) I'm 3/4 of a turn in from stock and it runs great
    #18
  19. Doug Matson

    Doug Matson Long timer Supporter

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    I think the air screws are really fuel screws that meter fuel instead of air, in leaner out richer. Air screws you find on 2 smokes on 4-strokes they are fuel screws I believe because of less vacuum. (Not trying to sharp shoot anyone just bored)
    #19
  20. motozilla

    motozilla Long timer

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    Do you have an aftermarket exhaust system?
    #20