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stock jets?

Discussion in 'CV Performance' started by jpaul, May 11, 2016.

  1. jpaul

    jpaul Member

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    I have a 93 fxr with SE pipes that have the baffles cut out and a Ness big sucker on it. When I bought it, back in 95, it only had the pipes done. I had a guy work on the carb for me because it ran bad. He said no one had adjusted it so he jetted it and opened up the a/c. Ran great for years. The past couple years it developed a cough or stumble. I had another bike shop look at it and they told me my diaphragm was bad and I should buy an S&S. Easy when it's not there money. Anyway I came across your site on bikernet.com so after some reading I picked up your slide, needle, tube, seems like I'm missing something. Anyway I started to wonder what the original jets would have been. It has a 42 pilot and 185 main in it. They were stamped with a k so they were original jets but maybe not to mine. When we checked the idle screw it was turned out 5 1/8 which seams like a lot compared to what I've read but it did run good and the fuel mileages was good, other than the cough. So I was wondering if I should just stay with them or change them too, Do i need to drill the vac port to 1/8 like Max did and I guess that's it. Oh I found out that the the acc pump diaphragm was bad so I'm replacing too.
  2. kenfuzed

    kenfuzed Administrator Staff Member

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    Hi JPaul and welcome to the forum.

    Ideally the jetting should be around 45 on the pilot jet. The 185 is fine and is at the high end of the jetting.

    The 5-1/8 turns on the mixture screw is troubling and I would think at that range the screw would be at risk of falling out. Did you mean 5-1/8 half turns (2+ full rotations)?

    Regarding the new slide, resist the temptation to drill it. We only recommend drilling a slide to a max of 7/64" if the slide is old, has burs in the port, or for those interested more in full throttle use. Your new slide is fine as it is. Many of the articles still in circulation refer to a 1/8th drilling, which was later debunked but few went back and revised those articles.

    What stands out for me is when you mention that the bike was running good for a long time and then began to develop the cough and stumble. This is most commonly due to a build up of lacquered fuel that begins to clog the passages after years of use or after any prolonged storage. The cure is to simply clean out the passages that connect the mixture screw, pilot jet, and front air intake hole. This is discussed on our troubleshooting page under item #3 at:
    https://cv-performance.com/harley-cv-carburetor-tuning-issues

    Make sure that when you clean that passage out that you take care with the mixture packing (spring, o-ring, washer) so they don't get lost or blown out of the hole when you apply compressed air. Cleaning those 3 access points to the passage with some diluted Dawn dish soap and water is usually all it take. Combine this with a #45 pilot jet, a general setting of 2-1/2 turns out on the mixture screw (give or take some fine tuning) and you should be good to ride.

    Lastly, I have to mention the same thing I always do - look out for vacuum leaks. A vacuum leak will fool you into thinking your jetting is too lean and if bad enough cause damage in the form of pinging and overheating. Check that the manifold boot is snug and not hardened with age. I recommend replacing the boot every few years and the accelerator pump diaphragm (you got that already) every other year or more depending on how bad the gas is in your area.

    HTH

    BTW, while many love their S&S carbs that is a whole other set of issues to deal with so stick with your CV carb.
  3. jpaul

    jpaul Member

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    I double checked with Sam, the guys that's helping me, he does a lot of small engine work. He said it was 5 1/8 out. I showed him your message here too so when I get the 45 jet we're going with what you said. I did notice that we were missing the washer on the idle screw when that came out, so one of the other two people that worked on it for must have misplaced it. So I'll have to get that kit too. one other thing and this might have something to do with it. There is a vacuum port on the back of the carb. I took the carb off and i don't remember a hose or anything connected to it. What's it for and or should it just have been capped off?
  4. hotroadking

    hotroadking Super Moderator Staff Member

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    It is the vac port for the stock fuel pet **** if you don't have it and have a gravity petcock then cap it off that's why you are 5 turns out


    Sent from my iPhone using Tapatalk
  5. kenfuzed

    kenfuzed Administrator Staff Member

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    On your 93 FXR you should have a VOES switch attached to that port.

    5-1/2 turns out on the mixture screw means that screw is close to falling out. HRK is right, if that back port is left open you will have a major vacuum leak and the mixture screw will need to be let out far too much to compensate.
  6. jpaul

    jpaul Member

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    It was that voes switch, I found the hose hanging there. I put the 46 jet in it and got it all back together and she purrs like a kitten. Or growls like a tiger. Thanks for the help. Now I'm going to put a tuner kit in my old ladies sporty.
  7. jpaul

    jpaul Member

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    I finally got the sportster done. Just a quick question on that. I put a Ness big sucker on that and cut the baffles out so I jetted it as the stage 1 with a 44/175.
    The carb has never been opened up that I can tell because the plug was still covering the idle screw. It had 44/180 in it, I guess i was under the impression that a guy should richin them up when you open them up. I put your new needle and tube in also. Runs good might need a little fine tuning but runs good. I guess I just want to make sure. Thanks
  8. kenfuzed

    kenfuzed Administrator Staff Member

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    Assume this is a different bike than what was being discussed last year in this thread. Are you using another one of our kits for this other bike?

    If you have a Sportster that had a #44 pilot jet and #180 main jet then it has been rejected from the stock sizes. You didn't mention if this was a 883 or 1200 engine and what year. Also if the Sportster is an 'S' model (dual plug heads) or a 2004-06 model the jetting is completely different from other Sportsters.
  9. jpaul

    jpaul Member

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    opps. Sorry, ya it's a 2001 883 sporty. Or maybe an 02 but ya. She bought used before we got together so I don't know any history on it other then it had stock everything on it and it having the plug still in the mixture screw I wouldn't have thought anybody had ever had it apart or jetted it.
  10. kenfuzed

    kenfuzed Administrator Staff Member

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    Ok, yes it sounds like someone changed jets but did not make any adjustments to the mixture screw. That is common at dealerships where touching that covered mixture screw is off limits due to EPA regulations. You are on the right track with the 44/175 based on this being a 883 model. Adjust the mixture screw as needed and if you still have problems with hesitation think about swapping out the needle for of our Velocity Needle.
  11. jpaul

    jpaul Member

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    I did use your guys needle also, and I replace the acc pump diaphragm. It was almost to the point of falling apart. Thanks for the help again.
    Jeff
  12. hotroadking

    hotroadking Super Moderator Staff Member

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    Sounds good two fixed...

    Remove the cover on the mix screw and fine tune it...
  13. jpaul

    jpaul Member

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    Yep did it. thanks

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