Wide-band UEGO 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. :confused: 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.
https://uniim1.shutterfly.com/ng/ser...nhance/O2a.jpg
https://uniim1.shutterfly.com/ng/ser...a-ZX-9RsE1.jpg
* 30-4110 is the full kit. The cheaper 30-4110NS version stands for No Sensor, as in no O2 sensor.
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.
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.
https://uniim1.shutterfly.com/ng/ser...nce/AFR101.jpg
https://uniim1.shutterfly.com/ng/ser...nce/AFR100.jpg
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:
https://media.tenor.com/images/d02ed...d0ed/tenor.gif
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.
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.