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  • Jetting the stock Roadstar Mikuni 40 carb

    Jetting the stock Roadstar Mikuni 40 carb

    Specifically in application to the Yamaha Road Star

    By Ken “the Mucker” Sexton
    August, 2007

    Whatever the motorcycle or automobile, virtually all carburetors (or “carbs” for short and not to
    be confused with the “carbs” which can affect your waist-line) work on the same principles and use
    similar internal systems to deliver fuel in the proper air/fuel ratio to the engine. Depending on the...
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  • Finding Intake Manifold Air Leaks

    Finding Intake Manifold Air Leaks

    David is a Technical Moderator, for Baron's Custom Accessories Technical Forum

    Your engine had been running fine. Recently it has started running poorly or backfiring, maybe when its warm, maybe when its cold or sometimes the problem just seems to come and go. The problem shows signs of both a rich and lean running carburetor. You have done the obvious like change jets, replace spark plugs, check plug wires and replace your air filter element, but the problem persists. You and your...
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  • Porting The Stock Manifold

    Porting The Stock Manifold

    Reprinted by Permission from Mr Tidy's Tech Tips

    (While Waiting For Greg's Manifold)
    Its not rocket science !
    Its really very simple - if you have the proper tool !!

    You need a variable speed Dremel tool with a course sandpaper covered cylinder that is about ½" in diameter. I use the one that came as part of the Dremel kit. Use the low speed setting. This tool really "Hog's" off the rubber! Take it SLOW AND EASY !!! At least the first time....
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  • Road Star Clinic Ported Manifold FAQ

    Road Star Clinic Ported Manifold FAQ

    What is porting?
    Porting is a term used to label the process whereby we decrease a manifold’s resistance to air/mix flow into the engines intake ports. On a Road Star, this process generally addresses the “T” junction in the stock manifold where the input from the carburetor meets the output tubes (or runners) to the individual heads. The stock Road Star manifold is literally the joining of two rubber tubes, including right angle junctions which can be radiused to smooth airflow and...
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  • Install the Nemesis Manifold

    Install the Nemesis Manifold

    With all the hulla-balloo lately on The Road Star Riders Forum about the issues involved mounting a stock airbox with K&N BAK and Nemesis Racing manifold, I decided to write a document to show ya’ll how easy it is to not only install the manifold but to make it work without a big deal using your stock airbox. The included parts list allowed for a perfect fit on my personal 2002 Road Star and should fit yours too. This document assumes you already have your bike stripped down to the point you...
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  • Installing a V.O.E.S. for the Mikuni HSR carburetor

    Installing a V.O.E.S. for the Mikuni HSR carburetor

    Understanding the VOES

    When I got rid of my stock carb and installed a Mikuni HSR42 flat-side, I was a happy camper except for one thing. I seemed to have a bit less power in the low and mid rpm ranges.

    This, I discovered, was because the Mikuni HSR carbs have no TPS. The stock, Mikuni CV carb has a built in Throttle Position Sensor (TPS) that puts out a small, variable, voltage signal. This signal increases in voltage as the throttle is rolled on. The ignition module, a black...
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  • Fabricating a TPS Driver

    Fabricating a TPS Driver


    All Road Stars built before the fuel injected, 2008 models vary their ignition timing via a small sensor attached to the carburetor. This sensor is called the Throttle Position Sensor -- or TPS. Theoretically, the more you twist your right wrist, the more demand is placed on the engine, and the less the ignition timing should be advanced. In real life riding this theory has a few holes, but in my experience the TPS still out-performs other available methods...
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    Last edited by Tykes_Place; 03-03-2018, 05:55 PM.

  • Installing a Genesis Carburetor

    Installing a Genesis Carburetor


    Some Road Star owners love the stock, 40mm Mikuni, CV carburetor. Others favor their aftermarket Mikuni HSR 42mm or 45mm, while still others are sold out to the S&S Super-G, using an aftermarket manifold.

    However, it is hard to argue with the incredible performance of the Genesis Big Air, 48mm carb from P.S.I. It is an enormous improvement, as others have also written. See Appendix-A for more information and my experiences with this amazing carburetor....
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    Last edited by Tykes_Place; 03-03-2018, 05:42 PM.

  • Dialing in your PMS

    Dialing in your PMS

    There are several methods of approaching the process of dialing in the PMS on the stock carb. This article outlines one method that can used, and which is designed to balance out the other circuits in the carb for best driveability.

    The Pilot circuit (which the PMS screw controls) is responsible for primary fuel delivery at idle and throttle positions below about 1/4 turn (see Bulldog's article for more complete explanation).

    All circuits in the stock carb are functional...
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  • The WOT test (Wide Open Throttle)

    The WOT test (Wide Open Throttle)

    This is a living document and will be ammended from time to time, as needed to make corrections, and as appropriate to accomodate new things as we learn them. We are still learning the benefits and potential misreads that can come from this test, but at this point the feedback has been very good, and it has helped to identify lean conditions in many main jets.

    This is a test that is fairly well known in Harley performance circles, and is now being adopted and adapted to the Road Star....
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