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Carb Quest

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  • Carb Quest

    Hi,
    I have searched the forums and I am unable to find the answer to my quest.

    A while back I had my bike dyno'd by a guy who did not have a lot of experience, he jetted my bike, Factory Pro with 106 jets mikuni (main jet) and the small velocity ring, as I left the dyno the bike surged like hell, (the dyno room was really hot), He replaced the mains back to Stock 110's mikuni mains and the bike ran fine.

    After much deliberation with myself and recalling the events of the day and a lot of reading of the instructions from Factory Pro, K&N, Dynojet, I came to the conclusion that the guy did not know what he was doing.

    When the large ring was fitted he tried various jets and could not get the bottom end dialled in, low RPM. not sure if this was WOT or not, so I do not know why he stayed with the small ring??


    My bike is UK spec 600cc katana, 5 ignition advance, K&N, full micron race system, it was Dyno'd with 110 mikuni mains as standard. With small ring fitted, needles 3rd, float level 14.6,new emulsion tubes (suzuki)

    I have fitted 117.5 mikuni mains and the large velocity ring as I feel / understand that if I can get more air/fuel mixture then this will increase speed - I tried the large ring with 110 mikuni mains I got masses of lean surging so much so it was like riding a bronco hence why I upped the size.

    Does anyone know the size change of main jets between the two velocity ring sizes as I am unsure as to if I have gone too large, and some people I have spoken to think that 117.5 mikuni mains might be a bit too large a main for a 600 and I do not want to pay out any more money for dyno time as there is no one I trust in this area (near Leeds UK)




    K&N filter #SU7592 instructions,
    Install the appropriate velocity ring.
    Small diameter velocity ring: To be used on a stock motorcycle.
    Large diameter velocity ring: To be used for increased air flow on a motorcycle that has a carburettor recalibration kit installed.

    Dynojet instructions,
    1. If you are running a K&N stock replacement air filter you will need to use a main jet that is 10 points larger. If you are using the DJ106 main jets you will need to install the DJ116 main jets. If you are using the DJ110 you will need to install the DJ120 main jet.



    Dynojet Jet Kits Whether you run a standard motorcycle, or a tuned sportbike, Dynojet Carburetor Jet Kits can provide you with a simple and affordable solution to all your carburetion problems. Dynojet Jet Kits increase power and smoothness throughout the entire rev range, while maintaining optimum fuel economy. Each Dynojet Jet Kit includes comprehensive instructions which show step-by-step installation and testing procedures to ensure a perfect setup every time. This is backed by free telephone and Internet support to Dynojet customers. Kit installation and Dynamometer services are available in many parts of the world. Please see the Dynamometer Center Search Page to locate your nearest dyno shop. Read Full Description Jet Kit Types Needle & Needle Jet Caps Many newer bikes have very flat power and fuel delivery curves when used with the stock exhaust and air-box. When aftermarket pipes are used, the power curve is usually not flat. You find the need to lean out for low speed and richen up for top end; or leaner on the top end and richer at the low speed. In order to achieve full function and driveability, Dynojet develops shrouds or cap style nozzles for adjusting the upper or lower top end. They also have an effect similar to fuel injection by breaking up the fuel as it enters the air stream. Fuel Needle The design of the needle is where Dynojet spends most of its R&D time. The needle is designed to give the correct amount of fuel throughout the mid-range and is also designed to allow adjustment from groove 1 to groove 6 with little or no effect below 3000 R.P.M.; then with the correct end dimensions, the needle will have little effect on the main jet regardless of needle position. This isolates all circuits from each other and ensures easy set-up of the midrange and driveability. Main Air Jet This jet allows air into the emulsion tube to mix with fuel being drawn up from the float bowl. It controls the amount of fuel which can be pulled from the float bowl into the venturi. The larger the size of the main air jet, the more air you get and less fuel. The smaller the main air jet, the more fuel you get and less air. Dynojet alters this only to achieve the flattest possible fuel delivery curve. Pilot Circuit This controls 100% of the engine idle and 25% of the transition onto the needle. Dynojet has found that the engine will idle with the standard pilot jet, with or without the air-box and with the slides and needles removed from the carburetors; therefore we never change the pilot jet. Doing so is proof that you are not using the other circuits correctly. Idle and off idle is controlled by the mixture screws and the float level which have the most positive effect below 4000 R.P.M. On some models the pilot air jet is changed to provide optimum fuel economy. Correct balancing of the carburetors also ensures a smooth idle. Main Jet We develop our main jets to correctly serve two functions; static load and dynamic load. The static load is the fuel received through the main jet in the upper gears, where the tachometer is moving very slow. The dynamic fueling portion of the main jet is the amount of fuel received from the jet in the mid-range potion of the power. For example, you have a GSXR1100 G,H with #130 main jets. You then install #125 mains. After running the bike you notice the top end has improved but the mid-range doesn't pull as well. You then install #135 mains and you notice the mid-range is great but the top end is slower. This is a common compromise when using stock main jets and needles. If you install Dy 93 Dealers Orders Dealer Orders "Dealer Orders Dynojet Research Inc. dealers much call in to place an order. Please call us at: 1-800-992-4993 (Toll Free)/Suzuki/Katana 600 (GSX-600)/1997

  • #2
    Guy shows up every few years.... Posts a question and disappears...

    How you been?
    I bet Arsenic might have your answer he know all about K&N filters...

    Comment


    • #3
      Originally posted by Black_peter View Post
      Guy shows up every few years.... Posts a question and disappears...

      How you been?
      I bet Arsenic might have your answer he know all about K&N filters...
      I've missed you too!!

      Comment


      • #4
        BP, I'm not gonna trash K&N filters, I've done that enough. UK spec bikes are different, they don't have all that emissions crap. PM superman tone, he's from the UK, and he says he gotten K&N to work fine.

        Comment

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