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  • Fuel injection facts & tips

    Every Yamaha dealership in the US.

    So this thread is easy to read, please add just tech tips here for fuel injected Roadstars. Don’t add non technical comments.

    Gathered from the old site from a lot of members in no particular order.

    * The stock ECU is not programmable. DK if it can be flashed by the dealer. Many have tried installing aftermarket ECUs (fuel processors) and many have eventually removed them because they couldn't get them to run right. Some folks have been successful.

    * There is no petcock.
    * The fuel pump is inside the gas tank.
    * Is there a throttle body?
    * Vacuum hoses?
    * Is there an accelerator pump?
    * O2 sensors?
    * How to clean?

    * Quote from Flyman1971 - He ran his bike with the stock ECU and duals for a week or so and decided on purchasing the Power Pro. He said the difference was unreal. A much quicker throttle response, alot more horses too, smoother acceleration, and a much cleaner burn! His machine was running too rich, now just a trail of water out the exhaust pipe. He did his research and all stock Roadstars run really lean, the black in the tailpipe is the tip. When he put the powerpro FI2000 on it ran a small stream of water out the exhaust now. This he is sure increased his fuel mileage by at least 15%. The Cobra PowerPro FI2000 costs around $550 and do not be fooled. They also have one for mid $200 range, but needs to be adjusted. I would pay the dif and get the one that programs itself 80 times per minute. He was weary on getting one because of the price, but he is glad now. Two of his buddies just ordered one as well after checking his out. You can install yourself within 45 minutes, very good step by step instructions. Good Luck and happy biking!

    * Quote from Gadgetman728 - Look at both ends of the small rubber vacuum hose under the tank that goes to the injectors. Is the end that came off the intake end soft, swollen, spongy, split? If so, the rest of the FI guys need to know this. I recommended this easy mod, but no one wants to do it. It made a new bike out of mine. That sensor, to me anyway, seems VERY important, and a perfect vacuum signal seems needed. Good luck, it's easy.

    The FI bikes seem to run really well under all conditions. I've posted several times to check that particular hose because of it's importance and it's proximity to fuel and the way the vacuum lines can swell, split and leak without much visual damage. This damage causes air leaks which the FI bikes HATE, trust me, I chased the problem for the first 6000 miles I owned my bike, with ZERO help from the dealer I bought it from, they were clueless.

    Late 2014 my 08 started having an intermittent error. After riding down the road for awhile at highway speeds, when I would need to slow down for a stop sign, as I decelerated, my bike would drop below idle and die. It doesn't do it every time, so it doesn't really effect too much. I rode all day Sunday 1-18-15, and it never happened once.

    The springtime tune up - new plugs, new gear and engine oil, filters and a vacuum line check is going to be done in a couple of weeks. If I find anything in there amiss, I'll post it.
    I wish we could adjust more things, but overall the Stock FI bike needs very little maint. or fuel adjustments compared to the carbbed bikes.
    It's interesting that Flyman1971 would state that all stock Road Stars run really lean then point to the black in the tailpipe as the tip. They run close to stoichiometric during closed loop cruise but richer at idle and at throttle settings above cruise. The rich idle is for smoothness and is the reason for the 20 minute idle cutoff. Keeps from overheating the converters and bluing the mufflers. The richer settings above cruise are for cooling especially during hot temperatures but are still in the max power range.

    The ECU is programmed by an engineer for a given volumetric efficiency. Change that and with the possible exception of closed loop the ECU won't adapt. Change it enough like the member with the 45mm throttle body and closed loop won't even adapt. That throttle body was intended to be used with the higher capacity injectors being sold back then.

    The FI bikes can be altered with exhaust, etc. but that won't necessarily make them faster. The stock ones are pretty darned fast.

    The 2 Tech Tips I want to submit here are:
    1) Even if your hoses are attached, they may have deteriorated and loosened over time. Don't just look at it and assume it's tight enough, take it off both ends and visually inspect it, mine was still tight at the sensor end, but swollen, over sized & spongy on the intake end. Spongy probably because of close proximity to fuel. - Change them and feel the difference.u
    2) I highly recommend Silicone Hi Temp Vacuum Tubing as a replacement alternative.

    If I posted some other time that the vacuum tubing was hooked to the fuel injectors, my error. I've always known, but may have explained it wrong once. The Vacuum tubing definitely goes from the nipple on top of the intake and runs straight to the sensor.

    And... as I keep preaching, this little hose is as important to FI bikes as Jetting & float adjustment on the carbbed bikes.

    They generate they're own voltage based not the amount of heat. The hotter they are, the more voltage... and the cooler the less. That's how they read the state of the exhaust gases, based not the amount of voltage the O2 sensor sends to the ECU; then the ECU adjusts the amount of fuel injected accordingly. If the O2 sensor is failing, they don't generate enough voltage. Think of it this way, if they bike is running lean, the exhaust temp will be hotter and the O2 sensor, via the ECU, will adjust the fuel mixture accordingly, there by making it more rich and cooling the exhaust gases. If the exhaust temp is too cold, the voltage level is too low and the ECU thinks it's running too rich and leans out the fuel mixture in the injectors. Get it?

    They're called O2 sensors for the purpose of monitoring oxygen present in the spent gasses.

    The zirconia sensors, once they reach operating temperature, do just that.

    I with a richer than normal mixture, not enough oxygen on the O2 sensor will drop the voltage telling the ECU to lean it out, and vice versa.

    Closed Loop

    The computer uses the oxygen sensor's input to regulate the fuel mixture, which is referred to as the fuel "feedback control loop." The computer takes its cues from the O2 sensor and responds by changing the fuel mixture. This produces a corresponding change in the O2 sensor reading. This is referred to as "closed loop" operation because the computer is using the O2 sensor's input to regulate the fuel mixture. The result is a constant flip-flop back and forth from rich to lean while keeping the average overall fuel mixture in proper balance to minimize emissions.

    When no signal is received from the O2 sensor, as is the case when a cold engine is first started (or the 02 sensor fails), the computer orders a fixed (unchanging) rich fuel mixture. This is referred to as "open loop" operation because no input is used from the O2 sensor to regulate the fuel mixture. If the engine fails to go into closed loop when the O2 sensor reaches operating temperature, or drops out of closed loop because the O2 sensor's signal is lost, the engine will run too rich causing an increase in fuel consumption and emissions. A bad engine temp sensor can also prevent the system from going into closed loop because the computer also considers engine temperature when deciding whether or not to go into closed loop.

    Closed loop mode is during cruise engine demands, for better fuel efficiency and emissions, and at higher throttle settings the ECU goes into open loop to a pre determined [richer] mixture setting for better power.

    This is the official tech bulletin from Yamaha 2/2/05 re engine noise.
    Explanation of engine mechanical noise characteristics
    XV1600/1700 Road Star models

    Please use the information in this bulletin to assist you in handling customer concerns about normal engine noise

    Yamaha designed the Road Star to be a very special motorcycle, the heart of which is it's enormous v-twin engine. Our goals were to build a big-bore, high torque engine in the tradition of classic motorcycles that have long been part of the American landscape. We also wanted it to have the exceptionally clean, muscular lines that without a doubt would draw attention to the Road Star.

    Several engineering decisions were made to accomplish our goals. For example, we chose traditional no-fuss air-cooling so as not to have a radiator detract from the bikes clean lines. We chose proven push-rod valve actuation to give the engine it's particular style, as well as it's particular height and weight distribution characteristics. We also gave it 98-102-cubic inch displacement-bigger than many car engines-with massive internal components like a crankshaft that alone weighs a hefty 45lbs.

    If a customer should question the overall engine noise level, explain to them that certain mechanical operating noises from the engine are expected, and the Road Star is no exception. It has engine-operating sounds that are inherent precisely because of the type of engine that it is. The air cooled engine design used for the Road Star, unlike liquid-cooled engines, does not have a sound deadening , liquid-filled jacket surrounding most of the sound-producing mechanical engine components. What is at issue is what are normal and abnormal noises.

    Remind the customer that this is a very large air-cooled engine. Aluminum and other metal components expand when they get hot, and the engine is designed with operating tolerances to accommodate for this expected characteristic of the metal. The result is that the customer will likely hear more overall mechanical noises from the engine when it's hot and the oil is thinner.

    Above all, make sure the customer is aware that the Road Star engine is proving itself to be extremely reliable and we are confident that Road Star will deliver trustworthy performance for years to come. assure them that normal mechanical noises are not the sign of impending engine failure.

    Engine Noise Analysis
    tapping noise from camshaft area

    Normal Noise
    During initial engine start-up, the customer may occasionally hear a tapping noise from the camshaft area and, within a few minutes, the noise subsides. explain that this is due to extra clearance at the push rod end before the hydraulic lifter is pumped up. When the engine is turned off and it stops in a position where one of the valves is open, that lifter will bleed down over time due to the constant pressure applied to the lifter by the valve spring. When the engine is restarted, a small amount of air may enter the lifter and it can take a few minutes for the air to bleed out of the lifter and self adjust to proper clearance.
    Abnormal Noise
    Constant tapping noise regardless of engine temperature - may be caused by what is called a flat lifter. if the piston inside the hydraulic lifter becomes scratched, the lifter will not be able to hold the compressed oil inside to take up the valve/push rod clearance. explain that a failed lifter will need to be replaced.

    Ticking Noise from Cylinder Head Area

    Normal Noise
    Explain that a light ticking noise is normal due to the compact air-cooled design of the cylinder heads, which allows the sound of rocker arm loading/unloading and valve-to-valve eat contact to be heard. Clarify that the ticking noise may increase slightly as the engine gets hot where the engine parts expand and the oil thins down.
    Abnormal Noise
    A consistently loud ticking noise, regardless of engine temperature may be caused by an improper valve clearance adjustment. Explain that this engine is designed with 2 intake valves and 2 exhaust vales per cylinder. The single rocker opens and closes both valves at the same time. One side of the rocker is nonadjustable and the clearance is self adjusted by the hydraulic lifter. The other side is adjustable and must be adjusted so the valve contact point is the same as the other side.

    Knocking Noise from Crankshaft Area

    Normal Noise
    When an extremely hot engine is idling, the customer may hear what some describe as a light knocking noise coming from the crankshaft area, primarily from the right side. The noise is more pronounced if the idle speed drops below 900rpm. this is a normal engine noise.
    Explain that the Road Star engine is designed to produce very high torque at low engine operating rpm. Because of this low operating rpm, for the alternator to produce sufficient electrical output to support the system, the alternator is driven off of a jackshaft which is geared to the crankshaft and spins at approximately 2 time the engine rpm.
    As the engine heats up and the aluminum crankcase expands, the gear lash (clearance) is increased between the alternator shaft drive and driven gear. Inform the customer that, normally, the oil viscosity dampens the gear contact surfaces and helps reduce mechanical noise. However, in this case, the oil is thin which reduces the damping effect.
    Under these conditions, if the machine is put into 1st gear and the engine is loaded down below 500 rpm with the brakes applied, the described knocking noise will become even more pronounced. Explain that this is because of several factors. 1st, the ignition timing is set for 900 rpm idle speed. At below 500 rpm, the timing is too far advanced and causes early combustion which will try to force the piston down in the opposite direction. 2nd, at such low rpm, the oil pressure is also very low which affect the damping effect at crankshaftplain bearings. Combine these factors with the slow spinning alternator shaft which is juddering from the magnetic field of the alternator rotor, the engine will make some mechanical noises. Reassure the customer that this is common with any engine design and does not indicate excessive wear/clearance of components or impending failure.
    Abnormal Noise
    If the engine is consistently making what is described as a knocking noise regardless of engine temperature or load, convey that it may be due to a bearing or bearing surface failure at the upper or lower connecting rod or crankshaft plain bearings. if your customer is concerned that a normal operating noise is impending bearing failure, remind him or her that bearing failures get progressively worse in a short time. if the noise hasn't been getting worse or even seems to "fix itself" from time to time, it's not a bearing failure.

    Roadstar Oil Filters

    BOSCH……………………….3300 or 3323 or D3323 Hi Efficiency
    NAPA GOLD………………...1358
    HI FLO………………………



  • #2
    Thanks for what you posted a while back Shores and getting the topic started. I agree the FI models run pretty good and trouble free. Did you find any issues when you did your Spring maintenance? I'm going to check that hose today. I have the same '08 model and I've been wanting to lower the idle for a long time. It idles around 900-1000 rpm and would like to get it more like 700-800. Even though I heard the idle is not adjustable I went in there to see what's there. Found the throttle body butterfly adjustment screw on mine and probably all other FI's does not actually make contact with the butterfly tab, instead it's backed off the tab to allow the butterfly to be fully closed across the throat. I was thinking wtf until seeing the idle air port located on the right side of the throat before the butterfly (about 1/4" diameter). Apparently this is the air idle circuit for the FI bikes. I could change the idle with my finger partly over the port but did not see any way on the throttle body exterior to adjust that idle circuit. Has anyone been successful at lowering the idle on an FI .. with any aftermarket ECU's.. or any other trick?


  • #3
    Someone on here told me the idle on the fuelies could be changed with an adjustment screw, buy why would you? Lowering the idle will decrease oil pressure and likely cause over heating or damage as well as will likely stumble when taking off from a stop. It’s not a Harley and never will sound like one since it has four valves per jug and other internal differences.


    • #4
      Do we suppose HD's new 'milwaukee eight' motors don't sound like a Harley..? Lol..


      • #5
        Nope, not adjustable.
        Scott B.


        • #6
          Originally posted by SuperG
          Do we suppose HD's new 'milwaukee eight' motors don't sound like a Harley..? Lol..
          No, they don’t. They sound meh!


          • #7
            Originally posted by texasscott1
            Nope, not adjustable.
            There is an adjustable stop screw for the throttle body’s butterfly shaft. Maybe, it is for fine tuning the final air flow to balance the idle speed control unit that is trimmed by the ECU for cold starts to add more air for a higher rpm and finally, the preset hot idle.

            The only thing mentioned in the service manual about the ISC is a high idle event where the valve hangs open and it is not serviceable where you just replace the throttle body. Ouch!


            • texasscott1
              texasscott1 commented
              Editing a comment
              I think that's there for the factory to adjust. I wouldn't be surprised if there was a dob of paint on it so someone could tell if it had been moved.

          • #8
            No doubt a factory only addition for final idle adjustment.

            Tho, mine is not tamper proof, nor any pics I’ve seen had the paint seal.


            • #9
              Anyone know if the catalyst is in the head pipe or the mufflers. I'd like to remove it because the excessive heat is almost unbearable


              • #10
                Originally posted by McVinny614
                Anyone know if the catalyst is in the head pipe or the mufflers. I'd like to remove it because the excessive heat is almost unbearable
                There isn’t a cat in the muffler. Just look up stage 1, 2 and 3 mods for Roadstar mufflers. It’s all over the interweb.


                • #11
                  Originally posted by Shores

                  There isn’t a cat in the muffler. Just look up stage 1, 2 and 3 mods for Roadstar mufflers. It’s all over the interweb.

                  The fuelies do come with them.
                  Attached Files


                  • #12
                    I'm thinking I read somewhere that they're in the muffler. I"m sure separating the head pips from the muffler it would be easy to look in both to see.


                    • Bikerron
                      Bikerron commented
                      Editing a comment
                      They are in the mufflers.

                  • #13
                    stage 3 mod doesn't get into the cat's though, right?


                    • #14
                      Put Dat bitch down about 500-550 rpm and let it lope.... Just be sure to let it warm up at idle 20-30 minutes you start it... Last longer Dat way.

                      Bump... Bump... Bump... Bump.....

                      Then retrofit a kick start and jockey shift and you would be da shit!
                      LET'S RIDE


                      • #15


                        • #16


                          • #17


                            • #18
                              The FI bikes also do indeed have a replaceable fuel filter.. The fuel filter is inside the fuel pump which is inside the fuel tank… certainly not an easy task to clean or replace but is very doable. My bike started running poorly at high speed/RPM and got continually worse.. I had previously had rust in the tank and had it cleaned but you never get 100% of it out.. Replaced the filter and problem solved.. Here’s a link to order 3 pack of filters.. I don’t know the OEM mfg. but these look IDENTICAL to the stock filter. IF you do remove your fuel pump make sure to order replacement fuel pump o-ring/gasket.. 5VN-24486-00-00



                              • Brad_G
                                Brad_G commented
                                Editing a comment
                                Great link to share!

                            • #19
                              Does anyone know the ID of the vacuum tubing that needs replaced? I don’t have my bike next to me and want to order the parts before I tear into it. Thank you!!!


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