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Thread: Wide-band Lambda AFR reverse SuperTrapp tuning and FAQ confirmation

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  1. #1
    Join Date
    Aug 2008
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    Blackfoot, ID
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    120

    Thumbs up Wide-band Lambda AFR reverse SuperTrapp tuning and FAQ confirmation

    As the SuperTrapp FAQ recommends, you should alter the number of exhaust diffusers, ride and determine if performance is more or less to your liking. Well, I now have a tool to take the guesswork out of the equation, confirm riding impressions, but arrive at the same desired result. This time, there's no arbitrary seat-of-the-pants impressions that could go either way. A wide-band Lambda sensor will give me 100% absolute real-time air to fuel ratio numbers to tell me how well I've tuned my Supertrapp and thus, my carburetors.

    The AEM wide-band Lambda AFR digital readout and O2 sensor (30-4110*) was installed last year on my 900 Ninja (ZX-9R). I recorded many of the results over a variety of riding conditions. Last years readings however were on a different motor, running different engine coolant. Since it was cheaper to swap to a younger motor than to even replace the oil seals in my 128,000 mile motor, I now have a much lower mileage motor, but also running waterless engine coolant.

    The combination of light oil leakage fouled my original AEM O2 sensor and eventually burned out the digital Lambda readout. One warranty replacement later, it's all working again and I have new numbers, different from before even though my carburetor jetting is mostly unchanged from before. I've confirmed my mid-range jetting is too lean, 15.2:1 lean at 55 MPH. Conventional SuperTrapp FAQ wisdom says to remove one or two diffuser plates to boost performance, get the AFR back below 14.7:1. Only this time, when I do, the AFR readout will tell me how much closer I am to ideal. My plan is to tune either only my SuperTrapp and/or my mid-range jet needle height to arrive at more ideal AFR numbers that I was seeing from the bike last year.

    For those wondering or a bit puzzled about how an AFR readout got on a carburetted motorcycle, it's aftermarket.




    * 30-4110 is the full kit. The cheaper 30-4110NS version stands for No Sensor, as in no O2 sensor.

  2. #2
    Join Date
    Aug 2008
    Location
    Blackfoot, ID
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    120

    Default What is one diffuser worth, removed?

    When it contributes 5% to the gap of combined diffusers with a closed end-cap, it's enough to drop AFR on my 899cc sportbike as follows:

    I don't know how to calculate surface area, so I'm just going with a numeric factor of the combined diffuser gap. AFR is about 0.2 lower up to 3K RPM, 0.3 lower at 3.8K/55 MPH and 0.5 lower at 4.7K/72 MPH.

    Once it's safe for an interstate tank run, I'll know more about how this translates. I have some numbers recorded from last month for a baseline to compare to. And I was already satisfied with mid-range oomph, but it feels like there's a little bit more. If that's just in my head, it did seem like I made a mental bookmark of how the bike pulled, lighted the front wheel. I don't remember it doing that prior to tonight.

  3. #3
    Join Date
    Aug 2008
    Location
    Blackfoot, ID
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    Post A little ride story

    Circumstantial riding last week. Got a wild hair after fueling in a couple gallons. Told myself that it was okay to put some miles on the bike up into the nearby mountains, just go easy, lean the bike, but take it smooth and slow. Noticed a car about a mile up ahead at the base of the mountain, waiting. Thought I was going to get lucky and they'd wait for me to come by them for whatever they were waiting for and I'd hit the jackpot on some clear sailing. Turned out to be two cars, a Suburu WRX (turbo?) and the lead vehicle looked to be an Audi of some sort (A4/A6), they pulled out in front of me conveniently. They were definitely going to hotrod up the mountain as a pair and since I was the last vehicle for a while that had gone by, they had a lot of room up ahead to play.

    Here we go. :no :evil: (my own worst enemy)

    Yes, I wanted to see what they had. I let them race into the first curve, while I held back. If they were really fast, I'd have my own room to play, but if they were slow, it was going to suck. The Audi braked into the corner, so he was pushing and actually appeared to come out of the corner pretty fast. I'm sure in their cars they probably felt like they were pulling some Gs and they thought they were going to dust the green sportbike. No way to tell until I dropped a knee down into the corner myself to find out.

    I made up several hundreds of yards on them in the first two corners and was already on the tail of the trailing WRX going into the third corner. He had to of seen me flying up behind him, b/c he gunned it going into a RH sweeper before a parabolic 25 MPH LH corner. He must have been beyond his comfort level though, b/c he was well over the centerline, sliding and throwing back a cloud of dust and debris at me, so I slowed and veered to the outside to avoid. They continued on and were making good time in the next faster 30 MPH corners, but up ahead was another series of 25s. I was only catching them a little in the 30 MPH corners, but I was all over them like a cheap suit when we got to the 25s. They were belching out a lot of black smoke and you could hear their engines whining and thumping along. There was every indication they were trying to run. Try as they did, it just wasn't working out how they probably envisioned after jumping in front of me.

    I was just carrying my energy through the corners in a fluid motion, lugging the bike around in 6th gear. The WRX must have gone in too hot or missed a gear on the second 25 MPH LH'er, b/c he lost a lot of momentum. I had to panic brake to avoid running into the back of him. Couldn't understand why they were going in so fast and parking it in the corners.

    Up ahead was slower traffic so I slowed to 50 MPH to let them as a pack move ahead, giving some spacing so I could have some fun in between catching back up to them. When I rolled on the throttle WFO I was probably at about 6,500' AMSL, the AFR went into the low 10s and the bike struggled to accelerate. :-k Rolling off a little brought the AFR up a little again and the bike lunged forward. Sounds like my mains are still too rich on average for the new engine and where I typically ride. I did my corners at my pace and caught back up to them about 1/4 mile ahead. The slower vehicles all moved out of the way and it was just us three and hopefully clear sailing. Again I let them take a sizeable lead, before turning up the pace going into the next sweeping corner. I began to get the impression they weren't good drivers, just kids who dumped a reasonable amount of money into their lowered cars, but sorely lacking in their driving skills & confidence. I could catch them at-will, which was turning out to be somewhat fun, somewhat aggravating. They'd accelerate to about 90 MPH on the straights and I'd stay down at about 55 to let them go, then as they'd hit the corners up ahead, I'd accelerate, take the corner without slowing, carry more speed into the next, reel them in at somewhat of an alarming rate and repeat the yo-yo.

    Having had my fun, point made, I turned around midway up. I think that was another fateful decision, b/c about two miles behind us was a state trooper coming up. He wasn't going terribly fast and I doubt he saw any of our dumb foolery, but I played it cool going back down and kept checking behind me to see if maybe he knew more than I thought and had turned to come after me. It wouldn't be the first time someone had called us in, but fortunately I never saw him again.

    Uneventful ride home and way way more than I should have risked given the S.A.H. orders. But it felt good to scrub the rust off and find some rhythm. It was also a little shocking about how it played out tonight, actually pacing cars that were definitely oversteering a bit in the slow corners. I'd read so many encounters where the results were the opposite, due to the greater contact patch of four tires on the sports cars. So the kids tonight must have really sucked! They made my night though!

    Coming downhill at about 60 MPH the readout was showing about 16.2:1 at steady coasting throttle, dropping from there if I gave it any throttle. Altitude didn't seem to make much difference. There was a headwind when I made the highway on the way back. Interestingly, at the same speeds on the return of ~75 MPH the AFR was about 0.4 leaner than with a tailwind on my way out, so the airbox pressures do translate to more air than fuel under higher airbox pressure conditions. In fact, they appeared to move directly proportional to wind gusts. So to carry that thought forward, my conclusion would be that AFR readings performed during dyno runs in static shop air are inaccurate to real world conditions.


    I've plotted the numbers into a spreadsheet, much like on a dyno chart, with riding impressions and mileage results...if that ever becomes a possibility.

  4. #4
    Join Date
    Aug 2008
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    Blackfoot, ID
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    Default Addressing some flat spot when going WOT

    This has everything to do with a motor refresh I did over the winter. The new engine doesn't like the old engine's carburetor settings. So right after, I dropped the main jets one step. But was still getting a too-rich condition only at WOT.




    So yesterday I dropped the main jets another step, but left the SuperTrapp diffusers the way they were. I want to see the results first, before maybe adding the one diffuser I removed back.

    That took care of the WOT/WFO flat spots, but was still able to occasionally get a 10 to show at WOT, so I might put the one SuperTrapp diffuser back. Noticeable pickup in midrange too by going with the leaner main jets. The lowest AFR witnessed was a 10.8:1 and it didn't feel like it prevented acceleration, even at higher altitudes. Only saw it for a split second, before the readings went more into the mid-11s. Mind you, this is on a RAM air bike, not one that relies only on atmospheric pressure.

    AFR at Idle is still about the same as before, but under acceleration I'm mostly seeing ~12.5:1. At steady throttle from 1.5K - 3.2K it gets continuously leaner as we all would suspect, then steadily drops from 3.2K to 5K RPMs anywhere from high 14s into the lower 13s. Above that it doesn't change much unless I'm accelerating hard, then no matter what the RPMs are, I'm seeing 11s & 12s. Acceleration is quite good even when it shows 11s, surprisingly. At higher altitudes doing some 6th gear roll on/off/on does kind of throw out some crazy numbers. Some of that probably has to do with exhaust gas lag in getting to the O2 sensor to be measured.

    In downhill riding scenarios at steady throttle it's common to see high 15s, low 16s. Off-throttle, low engine loading really doesn't mean anything other than that the engine isn't adding much fuel to basically spin the motor and to push what little drag there is being produced above 50 MPH. My bike seems to prefer anything from 11.0:1 - 14.7:1 on level ground, at speed.

    Throttle response and acceleration throughout the RPM range feels really good and meaty now. I can certainly live with how she's performing:

    Glad I have this device. I would not have thought the mains to be the current issue without it, but they were exactly the issue.

    Now to see how the bike performs at lower altitudes and what kind of MPG numbers the newer motor is truly capable of, without the handicap of jets that were about ~5% too rich for riding conditions.
    Last edited by kz550; 05-03-2020 at 08:44 AM. Reason: leave left wer/are

  5. #5
    Join Date
    Aug 2008
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    Blackfoot, ID
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    120

    Default Muzzy & stock muffler v. SuperTrapp, apples-to-apples.

    After several rides to lower and higher altitudes, the best compromise (carbs are a compromise), are their current settings with the diffuser back in place. I need it in there for the higher summits and it doesn't make fueling so lean it's an issue at lower altitudes. If I need to ride at one or the other for extended periods, I can add or remove onel diffuser, but fueling is really good. I'm not at the maximum nor the minimum diffusers, so for me, there is a sweet spot.

    But it gets better, because I purchased a second AEM UEGO gauge and wired up my other 2000 Ninja ZX-9R with a Muzzy pipe. With virtually the same jetting, the SuperTrapp bike is head and shoulders above the Muzzy bike in power and performance. I'm still looking to see if the Muzzy exhaust bike can do better at WOT operation with richer or leaner jetting than what's in it now. My sense is that one step leaner is the right way to go, but the UEGO readings off both bikes, say I should try to match the AFR numbers from the SuperTrapp as best as I can to the Muzzy. I know it can do better. I just got its mid-range a ton better, which is resulting in a parallel, but richer fuel graph from 1K - 8K RPM than the SuperTrapp bike's fueling. I definitely need to clean up the mains. At 3/4 - WOT, the Muzzy bike is definitely richer and too rich, making it obvious that 3/4 throttle works better for it than WFO throttle at the moment. But ironically when compared to the SuperTrapp's graph, it's leaner near redline and fluctuating more in the higher RPMs.

    The Muzzy bike is a work in progress, so this isn't conclusive for me yet. I'd like to try out different main jets to maximize the WOT performance, per Factory Pro's recommendation, which is to set the mains first and work your way down. Then I can fine-tune the mid-range and clean up the pilot circuit with the help of the EUGO readings.

    Comparing the two bikes:
    Off the line, SuperTrapp wins. Mid-range, SuperTrapp wins. Top-end, SuperTrapp wins. Rapid throttle response, SuperTrapp wins. Fuel efficiency, SuperTrapp wins. Exhaust weight, Muzzy wins.

    Haven't actually quarter miled my two bikes against one another, but I did run the SuperTrapp against another owner's 2000 ZX-9R. His is a lower mileage bike that I helped him rejet this Spring, running the stock exhaust, with a -1 countershaft sprocket for quicker acceleration. He confirmed the changes we made woke his bike up. Then we did about 10 first gear roll-on drag races through 3rd gear mostly him egging me on to show me how quick his bike was. The two bikes were evenly matched in 1st geary, but my SuperTrapp bike was basically walking away from his bike or holding it's own if his bike got the jump on mine. The longer the drag, the further my bike pulled his, even with his acceleration friendly gearing. While I was, I also wasn't surprised at how well my SuperTrapp bike did. This bike scares me enough to know it has a dangerous side that needs to be respected.

    Back to the Muzzy bike though, I checked the compression too thinking that must be contributing to it's lack of oomph, but its valve clearances are within specs and compression numbers looked good. So racing the two bikes wouldn't be fair to the Muzzy bike at the moment. It's just not ready and would get its clock cleaned.

    I'll know more in a week or two as I experiment more with the Muzzy's jetting. Since its exhaust flow is not adjustable like the SuperTrapp's, jetting is the only thing that I can use to adjust mixture readings. One way or the other, with the AEM UEGO gauge to help guide me, the Muzzy bike should improve to some level where I don't think I can improve it anymore. Then I can make a final determination on how it compares to the SuperTrapp bike. But I'm already eyeing my third 4" aluminum racing series muffler in place of the Muzzy CF muffler. I'm just not confident the Muzzy exhaust does as much for performance as the adjustable SuperTrapp. And performance is a motivator to make changes.

    p.s. once the Muzzy bike is tuned ideally, I have my baby, my 2002 ZX-9R (SuperTrapp) that is ready to accept the UEGO gauge too. It's much closer in performance to my 2000 ZX-9R, but I'll be curious to see if it too can benefit some after I draw out it's RPM fuel mapping and compare it to the other SuperTrapp bike. Stay tuned. There's more to learn.

  6. #6
    Join Date
    Aug 2008
    Location
    Blackfoot, ID
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    Default

    The Muzzy bike is still a work in progress. I checked the valve clearances and replaced the Factory Pro +4 ignition advance with a stock timing rotor. From a previous ride, I started to see a glimmer of hope, but the jetting was too lean though the midrange and too rich on top. So I adjusted the fueling some more, reducing the mains one step and bumping the jet needles up a notch to what Factory Pro recommends as a starting point.

    There's no way to sugarcoat it, the Muzzy pipe sounds sterile and stupid, like slapping your hands together in water when opening it up from 1/2 to WOT. Power is awful other than at WOT from 7K RPM up. The bike is just falling on its face by comparison, if I try to ride it like my other SuperTrapp ZX-9Rs. There is power and acceleration there, but it feels like its 15 HP down on the SuperTrapp bikes. For instance, rolling from a stop. With the SuperTrapp bikes, you almost don't need to go above idle while slipping the clutch. It's effortless. With the Muzzy bike, you have to rev it a little and slip the clutch for what seems like an eternity, by comparison. With the SuperTrapp bikes power is like a Tesla's powerful electric motor, it's instantaneous, everywhere and always on tap. With the Muzzy exhaust, if you want the same kind of power, you have to downshift a couple gears and by then, if it was an emergency, it's too late.

    But I'm still working on it and I'm getting closer now that the main jets are fairly close and timing isn't interfering. I know what I have to do next inside the carburetors, since I cannot tune using an adjustable exhaust, like with the SuperTrapp's easy to swap diffusers.

    FWIW, the AFR is still too rich, but primarily in the low-end and midrange. I think I can take some of that out, split the difference at the jet needle, it will hopefully restore some of the power that's not there like it could be.

    I'm serious, I feel like a sitting duck without the SuperTrapp kind of power I'm accustomed to. But I'm going to suffer through it until I think it's as close to ideal as possible, before ordering my aluminum racing series SuperTrapp slip-on. I just want to see for myself what other people experience. And so far, I can see why there are so many owners who are talked into putting on some other aftermarket muffler and soon after sell their bikes. I'm about to that point, except for the fact I know there's a soul in there waiting to be unleashed.

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