Evo CV carb assembly problem

Discussion in 'Engine, Fuel and Exhaust' started by Rollinlost, Sep 3, 2012.

  1. Rollinlost

    Rollinlost Member

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    OK guys, there has to be a trick to compress the vacuum slide spring so I can get the top of the carb together. I think I've tried pretty much everything but nothing seems to keep the spring from tweeking sideways before I can close the top. Does ANYBODY have a solution? I need to get this thing together. Oh yeah, this goes to my '94 evo cv carb (oem).
     
    Last edited: Sep 3, 2012
  2. Jack Klarich

    Jack Klarich Expert Member

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    Fuel and Carb Related Issues | Archive | HDTalking.Com Welcome to The Forum, have a look here:s
     
  3. Rollinlost

    Rollinlost Member

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    Hi Capital Jack --
    Just went over ALL of the previous posts that you referred me to and nothing covers how to get that vacuum slide spring compressed so the top of the carb can be screwed down. The diaphram is seated just fine; the spring seat is aligned so as not to block the hole in the bottom; the spring, however, has a mind of it's own! There MUST be a way to compress that thing so I can close the top of the carb without the spring getting misaligned. Aaarrrrgh!!
    (1994 Evo, CV carb, Dyna Wide Glide)
    Is there another guru out there that has some ideas on this?
     
  4. Jack Klarich

    Jack Klarich Expert Member

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    CV Carburetor Modifications :s
     
  5. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    The slide should be bottomed out in the carb body, with the plastic main jet needle holder/spring retainer in the bottom of the slide. There is a boss in the top/cover of the carb that holds the spring in place. Once you make sure you have the diaphram in the groove and you have the top boss in the spring simply lower the top and put in three screws. If the spring has not been streched it will stay centered. The hardest part of the whole operation is making sure the diaphram is in the groove and not pinched. Don't overthink the spring. Once you have the top screwed down make sure the slide works smoothly with no sticking points.
     
  6. Breeze3at

    Breeze3at Well-Known Member

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    Like Don posted above, the slide should be bottomed in the carb. body. There should be very little pre-load on the spring. It sounds like your slide is in the open (up) position?
     
  7. Rollinlost

    Rollinlost Member

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    The slide is in the down position and moves up and down freely without binding. The spring is 5-1/2 inches long -- dunno if this is standard or not but it came out of the carb this way and I haven't stretched it any. I can compress the spring against the top or against the spring seat with my fingers but as soon as I let go of the spring (to close the top), the middle of the spring tweeks to the side with most of it coiling around the diaphram; the top and bottom are still in their correct positions. I've tried compressing the spring, then holding it with a steel scale (ruler) while lowering the top but as soon as I try to remove the scale it not only rubs on the diaphram (don't want to tear it!) but it pulls on the middle of the spring uncoiling it into the diaphram.
    I've spent a total of probably two hours messing with trying to get the stupid spring compressed correctly and the top on -- I'm getting to my wits end!! And by the way, is it really essential that the spring seat not cover the hole at the bottom of the throat? It seems like any vacuum would raise the seat/valve needle enough to work properly anyway. And when I try to compress the spring, if it moves at all, the plastic seat moves to cover the hole. So far I haven't had a problem keeping the diaphram seated in it's groove... it's that darn spring that's giving me gray hair (more than usual).
     
  8. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    Is there a round boss on the inside of the top? If so put the spring down in the bore and use the top to compress the spring. I have rebuilt a lot of CV carbs and installing the spring is never an issue. Don't compress the spring and then try to install the top, use the top to compress the spring.
     
  9. Rollinlost

    Rollinlost Member

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    Yup, there's a boss inside the top. I've talked to three other guys that say they've never had a problem compressing the spring by just pushing down on the top (cover). So... I'm going to take it to each of 'em to see how they do with this monster. I'm optimistically hopeful that she'll come together and I can get the ol' scoot back on the road. In other words, I'm giving up; I can't seem to get the knack of "just pushing the top down to compress the spring" without it trying to jump across the garage and into my other bike's saddlebag. More on this escapade later, hopefully with some good news and maybe a "trick" for those of us who are spring retarded.

    Finally! One of the guys pointed out my problem -- the vacuum needle seat (the plastic goodie that the spring sits on) was installed, BY ME, upside down. So I've been trying to compress the spring on the top of the seat which, in effect, made the spring another inch long. The seat needs to be installed with the "feet" down, kind of like a sewing thimble. That gives the spring more of a guide so it doesn't tweek off to the side like mine was doing. I'm sure this is common sense to those that have messed with CV carbs before but the last time I had one apart was in the '70's. Now I see why everyone said they've never had a problem with closing the top on the carb. This took all of about a minute to remedy. Duh, here I am with my hand raised, I'm the idiot. But you can bet I'll never invert that spring seat again. :D
     
    Last edited by a moderator: Sep 5, 2012
  10. Jack Klarich

    Jack Klarich Expert Member

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    Lesson learned it is time to ride. We ALL make mistakes that is how our brains are wired. Glad you got it whipped:s