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Cams and Carb Kit

Discussion in 'Motorcycle Tech Talk' started by JohnnyBiker, Jul 16, 2010.

  1. JohnnyBiker

    JohnnyBiker Well-Known Member

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    I was paying attention to the posts when a lot of you were talking about cams. Most of you were saying that andrews is a good cam. I guess I am a person that like to have things that not a lot of people have. So, is there a cam that you recommend that is not so mainstream? I have tossing the idea around ever sincce I have gotten my bike to put a different cam, and possibly stroke it. What do all recommend?

    Also, I was on the phone with my indy shop today, when we were going through my carb, he had mentioned that there is a kit that is available that will improve how my carb atomizes the fuel. he did mention that I may gain 5 hp and a maybe a little better fuel economy. The kit is made by Yost. Does anyone have any experience with this?
    Last edited: Jul 16, 2010
    JohnnyBiker, Jul 16, 2010
    #1
  3. JohnnyBiker

    JohnnyBiker Well-Known Member

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    JohnnyBiker, Jul 16, 2010
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  4. mycle1000

    mycle1000 New Member

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    the yost power tube is a simple device that atomizes the fuel droplets into a fine vapor. i used one in a super e a few years back and do recommend it. i cannot say anything about the cams you are asking about.
    mycle1000, Jul 16, 2010
    #3
  5. HD97FXDC

    HD97FXDC New Member

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    Here is my 2 cents worth. Most people want to hear that nice rough or loping idle most of the cams that sounds like have the torque and horse power way out of the usable range for a street driven vehicle. Plus cams with high lift are tough on the valve train. In my opinion torque is what most people want and they want it to peak about 3500 to 4500 rpm whether they know it or not. This type of cam is better for pulling hills and passing especially if you are two up or hauling a trailer or gear. A high lift cam opens the valve wide reducing port velocity that is why it moves the HP and TQ numbers up in the rpm range. A lower lift longer duration cam will make HP and TQ at a lower rpm by not opening the valve as much and keeping the velocity up. Andrews cams has a nice section called pick your cam, check it out if you have not already. I would bore and stroke the engine there is no replacement for displacement.
    HD97FXDC, Jul 17, 2010
    #4
  6. JohnnyBiker

    JohnnyBiker Well-Known Member

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    I am not looking for a real lumpy cam, but I do want one that is set up that has good pull through the mid rpm to the higher rpm range. I really cannot bore my engine but I can stroke it. unless you know of jugs out there that I can put on my bike that are bigger that a 3.5 bore that will work without further mods?
    JohnnyBiker, Jul 17, 2010
    #5
  7. HD97FXDC

    HD97FXDC New Member

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    I have seen kits that claim to go to 88 and 90 CI" about 1442 cc's and 1474. The 88 does not require you to bore the case the 90 does. I think you will need some port work and head work to get the full potential out of this kit especially if you converted an 883 to a 1200. PM me and I will give you the link.
    HD97FXDC, Jul 17, 2010
    #6
  8. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Everything that I looked at in that link is for an 04 and up. OR did I miss something on that page?
    JohnnyBiker, Jul 17, 2010
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  9. HD97FXDC

    HD97FXDC New Member

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    I sent you a different link I did not know the year of your bike
    HD97FXDC, Jul 17, 2010
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  10. JohnnyBiker

    JohnnyBiker Well-Known Member

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    no problem, thank you.
    JohnnyBiker, Jul 17, 2010
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  11. JohnnyBiker

    JohnnyBiker Well-Known Member

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    So, I think that I would like to put a different cam in my bike, but am not sure of what would be a good fit for the bike. As I had said, I am not looking for a real lumpy cam, but one that would perform a little better throughout the whole power band? Does anyone else have any experience with the Yost Kit? If so, how do you like it, if not what do you recommend?
    JohnnyBiker, Jul 21, 2010
    #10
  12. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Ok, I called up Andrew today and I spoke to the Tech department. I told him what my bike is and that I am looking for a cam that is a good performance cam, but is not real lumpy. Well, I do not think that I am going to get away with that. So he proceeded to tell me that the N4 is the only way to go. So I went back their site, which stinks by the way, trying to look up what the specs are on the N4. Couldn't find them!!:gah:

    Does anyone know exactly what the specs are on this? When I was on the phone with the "tech" I asked several times exactly what rpm ranges that this cam is supposed to best at, he failed to answer it all times. :banghead:
    JohnnyBiker, Jul 30, 2010
    #11
  13. HD97FXDC

    HD97FXDC New Member

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    HD97FXDC, Jul 30, 2010
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  14. JohnnyBiker

    JohnnyBiker Well-Known Member

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    I took a look at that site and it still didn't give an rpm range. That is is a high lift, I am thinking that the rpm range on that cam would be about 2500-6000??
    JohnnyBiker, Jul 30, 2010
    #13
  15. HD97FXDC

    HD97FXDC New Member

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    HD97FXDC, Jul 30, 2010
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  16. JohnnyBiker

    JohnnyBiker Well-Known Member

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    I was close....
    JohnnyBiker, Jul 30, 2010
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  17. kenfuzed

    kenfuzed Administrator Staff Member

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    I refrained from commenting on this at first since I didn't want to come off as biased, given that I manufacture carburetor parts and Yost would be considered a competitor. However nobody else has commented so here goes. Just know that this is just my opinion, and like a-holes everyone has one.

    The Yost power tube is simply an emulsion tube that has been redesigned to mix more air with the fuel passing through the tube to create a finer air/fuel mist. Changing the mixture ratio being introduced will require rejetting that doe not fall under normal recommendation, in other words the increased amount of air is likely to increase the main jet size required. The power tube also incorporates the needle jet (nozzle) which on stock carburetors is a separate piece protruding up into the carb throat. For any unfamiliar with this piece, it directs the fuel spray and pattern as a nozzle while being regulated by the needle that moves up/down. The needle position determines how much fuel mixture is being delivered based on the movement of the slide.

    In the opinion of myself and many others there is a design problem with incorporating the needle jet (nozzle) with an emulsion tube as one piece. While it seems logical to make these components one piece rather than two, it requires that both be made of the same material. The reason the original needle jet is separate is because of wear. As the needle moves up and down inside the needle jet it will eventually wear the softer brass material. Because the jet is designed to provide a certain amount of fuel in a certain pattern, this will change over time as the wear increases. For this reason the original jet is made of stainless steel which will not wear, while the needle has an anodized coating to protect against wear from rubbing against the jet. It is imperative that neither the needle nor the needle jet wear as this changes the fuel pattern and amount of fuel delivered at given positions.

    If anyone wonders why a one piece tube could not be made of stainless, the answer is that stainless has a tendency to seize, plus is far more expensive to manufacture given the process and design. Same goes for titanium.

    Another issue I have with this product is cost. Since I manufacture my own emulsion tube that improves the same fuel spray (hence the bias) I know how much it costs to manufacture this component here in the US. I don't dispute that the Yost tube performs as advertised (same as the CVP tube) but $70+ seems extreme and a poor return on investment for the performance gained.

    Now my disclaimer:
    I do not personally have lab results showing the rate of wear when using a Yost power tube. There are plenty of tests and reports (Google emulsion tube wear) showing wear on other emulsion tubes made of only brass. Yost is not the first to use that design (they are masters of copying from others), as Keihin used similar designs on 2 and 4 stroke applications that have long been subject to wear issues. The statements I make are based on both my opinion and the experience of others. I am in no way publicly slandering any company and I'm sure Yost makes a fine product. Tubes that I have removed over the years from customer's bikes made by Yost, Dynojet, and others are all made of quality brass as is evident from the money I've made recycling the brass.
    kenfuzed, Aug 1, 2010
    #16
  18. HarleysLR

    HarleysLR Active Member

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    Great comments Ken.
    In other words it an’t worth the money.
    HarleysLR, Aug 1, 2010
    #17

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