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Runs bad at 3000 rpms

Discussion in 'CVP Stage 1 Tuners Kit' started by DanDman, Sep 27, 2012.

  1. DanDman

    DanDman New Member

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    I just recently installed a CVP deluxe kit on my '03 Dyna. I installed the #48 idle and #195 main jets. I'm running HQ0034 cams, SuperTrapp 2:1, SE stage 1 air filter, stock bore. The bike idles, accelerates fine. The problem is at 3ooo rpms it runs rough, surges. Before I put the kit in it would run even more rough at 3500 rpms. I had the stock cams, SE air filter, V&H Big Shots at that time. Any ideas what could be causing this problem? I'm thinking it is the rubber diaphragm, but I wanted to get some input before I spend $50+
    DanDman, Sep 27, 2012
    #1
  3. kenfuzed

    kenfuzed Administrator Staff Member

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    Has the slide ever been drilled (1/8" or larger)? This will cause erratic performance and surging. I would also check the exhaust flange gaskets. Since 2-1 systems have a fixed fit one seal could easily leak if both are not torqued evenly. Also it is important that those gaskets be replaced EVERY time you remove the pipes. the way they crush when installed makes them prone to leak if reinstalled a second time. An exhaust leak will draw cooler air back toward the exhaust ports under certain loads and contribute to problems normally associated with the carburetor. Jetting and mixture settings can be adjusted to compensate but the root problem of an exhaust leak should always be checked and eliminated.
    kenfuzed, Sep 27, 2012
    #2
  4. DanDman

    DanDman New Member

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    I drilled the slide with the 7/64 bit. The CVP kit wasn't installed when I was running the V&H system and I was getting the same symptoms but worse at 3500rpms. I installed new gaskets and flanges when I installed the pipes. I ran the bike and let it cool down and retorqued the bolts. I've listened at the exhaust ports with a hose and stethoscope and didn't hear any leaking. I followed the CVP instructions when I did the carbuerator. When I installed the Supertrapp pipes they suggest a 180-195 main jet, 50-60 idle jet. They also say to move the needle clip from from the top groove to position #5. (?) I'm going to try testing the intake manifold for vacuum leaks and see if that leads to any thing.
    DanDman, Sep 27, 2012
    #3
  5. DanDman

    DanDman New Member

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    I went out to garage, warmed up the bike and checked with propane for vacuum leaks. Bike ran the same with no changes. I used to do the same thing checking for leaks with carb. cleaner or wd40 on car engines, less of a mess with propane! I ran the motor up to 3000 rpms and higher. Definite stumbling/miss at 3000 rpms. That's not present at higher or lower rpms.
    Last edited: Sep 27, 2012
    DanDman, Sep 27, 2012
    #4
  6. DanDman

    DanDman New Member

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    Is there any other ways to check for exhaust leaks? What is perplexing is that I had similar symptoms before I did any changes. The only prior carburetor mods I could see was that the mixture screw plug was removed.
    DanDman, Sep 27, 2012
    #5
  7. DanDman

    DanDman New Member

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    Ok, I changed the spark plugs. Made a visual check of the wires, I couldn't find what the resistance should be in the manual. Fired it up and no difference at 3000 rpms. I did notice that the rough running starts at about 2500 rpms.
    DanDman, Sep 27, 2012
    #6
  8. DanDman

    DanDman New Member

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    Well so much for tech support. I bought my CVP deluxe tuner kit thinking that it was backed up by good tech support. It's been 4 days and 1 response and no other suggestions. Maybe I'll try another forum. I may get some useful suggestions, so I can resolve my issue.
    Last edited: Oct 1, 2012
    DanDman, Oct 1, 2012
    #7
  9. cowboy

    cowboy Moderator Staff Member

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    try a different needle since you did drill it out , not sure what size you'll need but a little bigger
    cowboy, Oct 4, 2012
    #8
  10. DanDman

    DanDman New Member

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    I did some searching and found a video showing a good diaphragm in action and a bad one. I had a bad one. Since this was my first rebuild I didn't realize the carburetor had a Thunderslide installed previously. I don't know if it was bad before I drilled the hole and redid the jetting. I had ordered a new slide/diaphragm. I just got done putting it in. I started and ran the bike while it was on the lift. I does to run better. Starts and idles good, revved it up and held it at 3000 rpms seems smoother. I'll find out when I ride it tomorrow.
    DanDman, Oct 4, 2012
    #9
  11. cowboy

    cowboy Moderator Staff Member

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    Sounds like your headed in the right direction , & have it close enough to run right , we all here have been busy in our privet life's sorry it took so long getting to ya
    cowboy, Oct 5, 2012
    #10
  12. kenfuzed

    kenfuzed Administrator Staff Member

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    Hi Dan, sorry thought you were following the tech support sent by email.

    Part of the problem is you are using a combination of parts that don't work with each other. Thunderslides don't work with any other part (including stock or CVP) other than their own (DynoJet brand).

    Your mention earlier in this thread of a needle with clips also indicates that you are not using what was included in the CVP tuners kit which makes it even more difficult to troubleshoot. My recommendation is to completely remove the Thunderslide and all related components (slide, emulsion tube, needle, spring, jets) and start fresh with what was included in the CVP kit. You will also need a stock slide. Luckily you should already have these parts to replace in the CVP kit you purchased, other than the slide. This is the only way to establish a solid baseline and begin tuning from there. CVP parts get along with all stock parts, which is not the case with the Thunderslide or other DynoJet parts.

    HTH
    kenfuzed, Oct 5, 2012
    #11
  13. DanDman

    DanDman New Member

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    I did use the CVP kit needles. Being that this was the first time doing a CV carb, I didn't realize I had Thunder Jet slide installed by the previous owner. The part about the clips on the clips on the needle jet where from Supertrapp's instructions for jetting a carb., I think the're describing a EVO era carb. Well anyways I got everything straightened out by installing a new slide.
    DanDman, Oct 6, 2012
    #12

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