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Thread: Ignition timing map assistance requested.

  1. #1

    Default Ignition timing map assistance requested.

    At the risk of loosing potential respondents, this is for a motorcycle application. Kawasaki ZX14 bored/stroked with multiple stages of nitrous. Prior to a crash all worked as expected. I rebuilt with a Dominator to have one controller instead of multiple "black boxes". I have the bike running, while not fully tuned, it's currently 209 HP to the rear tire on C16.

    I can't shake the feeling the ignition map is entirely wrong. Since the bike is drag race only, I don't really need timing that reflects cruising/fuel economy so I employed a "best guess" method and tried to tune from there. I've got a good idle, dyno runs at wide open show meaningful HP gains roll off around 38-40° BTDC. "Blending" the cells in between resulting in harsh stumbling and an occasional flame throwing backfire. As an experiment (and to my surprise), if I map everything (except idle) at 38° BTDC and fuel all corresponding cells to 13.0 AFR, it seems to run fine at all RPM, although I'm certain I'm washing the cylinders with excess fuel at anything other than max RPM.

    So is the objective to acquire a stock ignition map and do a copy/paste? Can I map all cells at a given (what would it be?) timing value and fuel the mid-range leaner (15-16 AFR?) to simulate a stock cruising/fuel economy timing map?

    Thoughts? Suggestions? If the objective is to use a stock ignition map, does anyone have access to one? I acquired a stock ZX10 timing map, but it made my bike pop/fart at every RPM. Your help will be greatly appreciated before I just cross my fingers and spray! Thanks.

  2. #2

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    I'd be looking at all aspects here. Have you verified static timing? Revved it up? Even faulty coils can cause this, or coils that fire early to protect themselves from over dwell.

    If you stop having gains or the gains are not meaningful at 38° stop there. Was this across the entire band or at just one RPM point? Dyno pulls need to be across the entire band at various advances to be meaningful.

    A target of 13:1 isn't going to wash down cylinders. You could go leaner at cruise, but you don't *need* to. The other issue is how much do you trust the wideband? They tend to show false readings at lower RPM with anything with a cam. How well does actual AFR follow target?

    Try a target of around 14:1-14.5:1 at idle and cruise. Blend in between. Be careful where you are putting 38. At lower rpm this could easily be too much. Go take a look at how some of the Holley tables are blended. Don't worry about doing a target leaner than stoichiometric since this is a drag only vehicle.

  3. #3

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    Thanks allah5oh. I'll attempt to answer each question posed.

    Static Timing was verified. I drilled a hole through the timing cover, installed a "pointer" and using a timing light triggering off cylinder #1 I got 14° offset which was entered into the applicable software field. Re-timing with this value entered saw the light triggering correctly. I don't remember the exact name of the applicable field (I don't have the software in front of me), but when I revved the engine with this offset entered, there was no timing drift.
    Coils are factory Kawasaki using the Holley driver for 2-wire "dumb" coils. I can't answer anything about "protecting themselves".
    Static dyno pulls were conducted at 7,8,9 and 10,000 RPM column making incremental changes to AFR and timing (not at the same time). 7 and 8,000 RPM stopped making meaningful gains at 13.0 AFR and 38° timing - 9 and 10,000 stopped making meaningful gains at 12.8 AFR and 40° timing. (NOTE: I still made 1-2 HP gains past these values, but I don't perceive them as a beneficial for the excess stress placed on the engine). Entering the above noted values into the software, I then ran some "full pulls" on the dyno. Results show a very linear HP increases through all RPM ranges (slightly leveling out around 9400 RPM but still noticeably increasing).
    The wideband is new. Using the dyno's 5 gas analyzer, I transferred the data from a "full-pulls" into an online Lambda calculator (Brettschneider Equation). The resulting AFR from the equation shows the exact same AFR the WBO2 sensor is reading/calculating fuel load.

    Now for my follow up question. Holley's information if automotive based, wouldn't the base timing tables for a V8 be significantly different than a high RPM inline 4? If I understand correctly, most timing maps are at max not that far into the map. If I use that logic, if I put my idle zone at 14.7 (ish) AFR and 28° would that create a better timing "blend" over a relatively short timing range? The factory ZX10 timing map I accessed had idle down around 18° if I remember correctly. I couldn't get the engine to start.

    BTW, thanks for chiming in. I wasn't sure I'd get much help after stating this was a bike.

  4. #4

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    It is possible you had a lack of air to keep it running, not a lack of timing. I don't have any direct experience with bikes, so I can only give you general ideas. With V8s it seems like they want to idle 10-15° lower than their WOT timing. Keep an eye on idle spark control, it will add or pull 8° to keep your RPM stable at idle. For a good quality idle you want to play with more timing/less air and less timing/more air. What I find is it is easier to start with more air and less timing, do a TPS Autoset, add timing and slowly close the TB. That way you don't have to do constant TPS Autosets. I bet you'll get this thing idling great.

    I would say 38-39° is good at 13:1 AFR. Then the question is how do we blend from idle to WOT? I would certainly try stretching the blend over a much larger RPM range than a typical V8. Heck I might even only do 34-36° until higher RPM just to keep things safe. You don't spend much time at lower RPM anyways.

    Another thing to pay attention to is your RPM per second gain. If you dynoed at a very low RPM per sec, but at the track it's much higher, you will need to add timing. And vice versa.

  5. #5

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    I only got to make a couple low speed runs on the last track day - more to verify mechanical soundness not speed. The timing concern came from horrible engine performance riding to the start line and back to the pits - all low speed and rpm events
    Snow is on the ground (hello from Canada!!!) so I can only test on a dyno at this point. I'll most likely make some pulls next weekend - please keep an eye open for this thread as I'll update with results
    Thanks again

  6. #6

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    As an option: Is anyone aware of a motorcycle tuner (with Holley EFI experience) who has online tuning abilities? Someone who can review data from dyno runs I make and provide feedback?

  7. #7

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    I'd talk to Andy Whittle. Tell him Allan sent you. You can find him on Facebook.

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