Data Logging for tuning your KZ

Wow, it's been six weeks since I updated this. Now I can hopefully make some real progress. I got a permanent source of power wired for the LM2. It's just as simple as tapping into the brown circuit in the factory harness. This is hot with the ignition on. It's important to have this automatically powered every time that the bike is started. If not, then the sensor will get covered in soot from the exhaust, and ruined.

Now, since I have the Dyna 2000, I have an easy source for an rpm signal. The Dyna has outputs for an electronic tach. So just wire the green output into the LM2 tach input and now we're logging AFR and RPM.

Now in order to use the other two sensors I need a source of 5 VDC. In my research, I discovered that a USB plug outputs 5VDC to the outer two pins. So I dug up an old video game car charger that I had. It's the kind that plugs into your cigarette lighter. I popped open the case and wired it straight to the battery for testing. If you touch the outer two pins with your multimeter leads it reads 5.4VDC. This should do for running two sensors.

The tricky part is getting an attachment point for the throttle position sensor. I think that I have it figured out, and I'll post pictures as soon as I get it. Hopefully, I can sort it tomorrow. I found some old RC car turnbuckles that are just the right size, and will allow me to make the link between the TPS and the throttle bellcrank on the carbs.

I wonder how hard it would be to run DynoJet's AutoTune box on a FI bike?

Obviously everything would have to be custom fabbed, but you'd probably have the only "AutoTuned KZ" out there!

OK, who's hogging the popcorn? pass it over.

mtbspeedfreak wrote:

I wonder how hard it would be to run DynoJet's AutoTune box on a FI bike?

Obviously everything would have to be custom fabbed, but you'd probably have the only "AutoTuned KZ" out there!

As I understand it, the AutoTune is an add on to the PC V series of PowerCommanders. Those are only available for late model bikes. As an example, I can't even get a PC V for my 2004 ZX-10r, it's not new enough. I guess that you could adapt the fuel injection from a new bike, but it would require major tuning to work with a KZ. I'm not interested in getting that involved in this particular project. If I were going to switch to fuel injection, then it would probably be a Megasquirt system. That seems to be the most cost efficient and user friendly option for the DIY market. The megasquirt would still have to be tuned manually by logging data in the same way that I will be demonstrating in this thread.

Actually that's the whole point. I want to learn to tune the good ole carbs this way as a learning exercise. Once I get the KZ running good, and compare a few different things like baffles, whole exhaust, carbs, and possibly airbox options, then it's on to the Ninja to build my own custom map for my PC III USB.

I already discovered that the datalogger simplifies the task of setting pilot needles. With it displaying instantaneous AFR and RPM you can see where you are at without even touching the screws one time. Get the bike warm and idling stable then have a look at the LM2. Ok its idling at 990 rpm and AFR is hovering around 12:1. A little too rich so you turn the pilot screws in half a turn and the AFR jumps up to 15:1 and the idle is up to 1200 rpm. Then back the screws out a quarter turn, now I'm at 13.2:1 and 1100. Keep going until you get the highest idle and I'm shooting for about 14.0:1 at idle due to 10% ethanol content.

It's so much more accurate than the cable driven tach, so no guesswork on what the highest idle speed is. Also it's remarkable how small changes to the pilot screws affect your AFR at idle. To really get close, you are making 1/8 turn adjustments in the end.

that would be very nice with the rs34 carbs i have. they only have a 1/2 turn window for the pilot screws.
impossible to tune very accurately by ear really.
i can tune the stock carbs close by ear, but probably not to 1/8".
i supose u will need to resync when u are done.
very cool.

OK Gotcha. I must say, I am definitely interested in how this turns out for you!

What carbs are you running? 29mm smoothies?

I second that... about the 1/8 turn increments.

Temperature makes a big difference on the idle AFR as well. For me, on a normal summer day, I may start out around 13 to 14 at idle, but by the end of a 1/2 hour ride, the idle may be as rich as 12 AFR. Also, this leads to the idle speed climbing with temperature.

What I found is that if you set idle just slightly rich while it's at full temp on a hot day, like say 11.5 to 12, then the idle speed does not climb as much as it warms up.

Also, at full temp, the idle is much more steady for me in the 12 to 13 range, as opposed to the 13 to 14 range.

I don't know what the high Ethanol content will do to these numbers, though. I haven't used it.

Can't wait to see how you rig up the throttle sensor. That's the one thing I plan to add in the future.

I'm surprised to get so much positive input. I figured that everyone would try and get all old school on me an gripe about me hanging computers on my 33 year old bike.

Mark, I will definitely have to re-sync after all is said and done. I had to take the #3 carb off the rack to get the throttle bellcrank out. I had to drill a small hole in it for my turnbuckle to mount up.

mtbspeedfreak, sadly these are just run of the mill VM26ss carbs. I actually want to start out pretty stock, so that I have a baseline to compare any mods. We'll call these the control carbs. Remember science class, ohno! If you have a set of 29's to donate for testing, I be glad to take them off your hands. :laugh: I promise I'll return them. :evil:

loudhvx I did some research, and IIRC the correct AFR for 10% ethanol blended gas is 14.0:1 as opposed to 14.7. I'm hoping to get it tuned for about 12.5:1 on the power since I have learned that you want to be a bit on the rich side for best power output. The other day when I rode it to work, it was idling in the 12-13 range and as soon as I got into the pilots it would get down to 10:1. I decided to go down one jet size and then re-tune my pilot needles to see if that gets me more in line.

I'll try and post what jetting changes I make here for a reference. On the ride to work I had #20 pilots, needles on the 4th clip and #120 mains. Slightly rich at idle, rich in the pilots, and slightly lean from 1/4-full throttle. It was a 60*F overcast day, and I am at sea level. I believe that I had a fuel filter on the way out that was causing the lean condition at higher throttle. I re-checked the float levels and they are spot on at 1/8" below the flange. Next test will be with #17.5 pilots, pilot needles re-set, needles on the 4th clip, #20 mains, and new fuel filter.

I got a small start last night on attaching the TPS, but I'll wait to post the pictures until I have it 100% sorted.

I'm surprised to get so much positive input.

:laugh: :laugh: :laugh:

I love what your doing... but... keep in mind for later...

The pilot mixtures and jetting (when viewed individually via 4 O2 sensors, or colortune plug, or...) are all different. Always. Never had a bike EVER where they fell at the exact same spot at any given time.

With these bikes, you are tuning 4 small engines to work together, because of the 4 individual carbs. you can probly get things real close...

Almost all racers end up using different jets and air jet combinations across all four carbs in the end to produce REAL maximum power. Even seen guys half-drill a jet between sizes.

Nice setup, but it needs to be on a dyno. All your data will change, once there is a significant load against the engine. AFR is fine and dandy to measure, but power is what comes out and pushes you forward. MAX power happens when AFR is actually all over the place throught the throttle/rpm range. You'll see...

Best of luck, and have fun.



Oh yeah, and someone said this before, but there is WAY more than just 3 simple circuits to tune WWWAAAAYYYY more. Read this: VM Round Slide Tuning Manual

:silly: Here we go... :silly:

Good points TeK9iNe. I will actually be logging data under a load while riding. It get's stored to a memory card for later review on a PC. I also plan to address the ability to quantify my power output. Just wait and see on that one. I need to get caught up from Christmas for that aspect.

Thanks for posting the tuning manual. I actually downloaded that one before. I'm just going about this the same way anyone new to this should. Let's get the bike running decent first then we can get into small details. Not sure I'll ever get into it to the point of running four O2 sensors. That seems like overkill on a street bike, but I agree that it is near impossible to have four cylinders with four carbs doing the exact same thing.

I'm dealing with mechanical slides, and if I make the mistake of cranking the throttle open too fast, I can easily go down into 10:1. But I can feel the mistake because the throttle pull gets way too light which tells me I've opened too fast and the vacuum has dropped too much. I think that's the exact problem the CV's are trying to eliminate, so I'm not sure what will happen on your carbs.

Since the mixture always gets richer when you open the throttle, it's a matter of throttle control on mechanical slides. I can also open it slow enough that the mixture stays at close to 13. So for me, I have to try to keep throttle control consistent while watching the AFR gauge.

Keep in mind, as the engine speed catches up to the throttle positiion it leans out rapidly from where it was buried.

I seem to get best power if, in a hard launch, I get the AFR to swing from about 11.5 to 13 just before I shift. This means the AFR sweeps through the sweet spot somewhere in the middle of the power band, hopefully.

But if I tune for best power, at a particular temperature, it will be too lean on cooler days, and will be way too lean for a much longer peiod after initial start until the engine comes up to temp. I think for best overall power and drivability, you should end up slightly rich on hot days, and a little lean on cold days. This will still be perfectly drivable on all days, but after some time, you'll get to notice there is a tick less power on super hot or super cold days. At least that's been my experience (even before I had the o2 sensor). The problem is, the AFR gauge now shows you how much you can correct it etc. so you actually spend more time tuning, rather than less, because you know you can get it just right, rather than settle for good enough. :laugh: