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Thread: Suzuki GT750 EFI Special

  1. #76
    Clearly like all micro's, if there is noise around it will probably generate issues.

    After a couple of weeks of trials, the items below, in order of importance, seem to be what helps the most for a small space, bike design.

    1. Resistor plugs (ones with a R in the code)
    2. Resistor caps, initially I was worried about the additional 5k resistance but so far (pending dyno) they seem fine.
    3. Silicone/carbon (not copper wire) ignition leads
    4. The USB cable to run Tunerstudio live with must be high quality and not too long, also I found that using a couple of ferrites with at least one coil of USB inside, helped. Noise on the USB line will cause sync loss.
    5. Wires between Speeduino and the trigger unit and from the trigger unit to the coils need to be screened cables. I use one for each coil feed with the earths connected at each end, which seemed better than a single ended earth.
    6. The +ve to Speeduino benefits from a ferrite with at least 5 coils wound through it
    7. The 0v to Speeduino also befits from a ferrite fitting

    The latter two (6,7) need some more evaluation, as most of my problem was poor quality resistive plugs and caps and until I had those replaced, all of the above made improvements. I suspect that with quality plugs/caps, some of the other changes may not be required but again as a tight space build, they may still be useful.

    Thanks everyone for the pointers. The real eye opener for me was the USB cable, I should have thought it would be an issue but didn't look there initially but it makes sense as its a direct line to the micro.

    So all good. Final hurdle was to remember to zero the coolant and air temp sensor compensation curves (as I am not bothered about those sensors until I add the injectors) because they retard the ignition as an offset to the basic spark table and it turns out I was initially running at 15 degrees at startup (should be 24). I am amazed it started at all....the clue was running rich obviously.

    Speeduino/Tunerstudio is pretty amazing but lots of ways to trip up!

    Quick road run this week then back to the dyno then the fun starts with the injectors!

    I am going to leave them in the throttle bodies as a starter then move to the crankcase later after another dyno run.

  2. #77
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    Quote Originally Posted by Kettlekev View Post

    1. Resistor plugs (ones with a R in the code)
    2. Resistor caps, initially I was worried about the additional 5k resistance but so far (pending dyno) they seem fine.
    3. Silicone/carbon (not copper wire) ignition leads
    4. The USB cable to run Tunerstudio live with must be high quality and not too long, also I found that using a couple of ferrites with at least one coil of USB inside, helped. Noise on the USB line will cause sync loss.
    5. Wires between Speeduino and the trigger unit and from the trigger unit to the coils need to be screened cables. I use one for each coil feed with the earths connected at each end, which seemed better than a single ended earth.
    6. The +ve to Speeduino benefits from a ferrite with at least 5 coils wound through it
    7. The 0v to Speeduino also befits from a ferrite fitting
    Thanks for the tips. Very helpful.

  3. #78
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    Quote Originally Posted by Kettlekev View Post
    Quick road run this week then back to the dyno then the fun starts with the injectors!

    I am going to leave them in the throttle bodies as a starter then move to the crankcase later after another dyno run.
    My first step was to get it idling. Then I set the wide open throttle cells. I found wide open throttle was easy compared to trailing throttle.

    Yours is a very interesting project. Good Luck.

  4. #79
    TZ350,

    Did you ever post your spark table anywhere? It would be interesting to compare.

    One more caution note on Speeduino and spark table.

    Whatever you set on the spark table is affected by the cold start setting for IAT and CLT sensors.

    There are offset temperature curves for both and if you dont check/set them you will have an offset to the standard spark table. If you are not using the sensors its best to run them to ground through say a 10k resistor and then calibrate them so that they read something sensible. If you dont, they become a floating input that can cause issues.

  5. #80
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    Quote Originally Posted by Kettlekev View Post
    TZ350,Did you ever post your spark table anywhere? It would be interesting to compare.
    Hi Kettlekev. No I don't use the Speeduino spark side of things at all as I knew nothing about the car coil packs required and how to set them up.

    I have continued to use the Ignitec digital 12Volt DC/CDI 2 cylinder Race system I had on the bike. I would love to know more about the details of the coil pack you use.

    I will post a picture of my ignition curve if you like. But as the engine peaks at 12k rpm and the ignition goes into heavy retard to heat the pipe for additional over rev I am not sure it will be very helpful.

  6. #81
    TZ350, the coils are the 0.5 ohm dynatek ones. https://shop.dynatekuk.com/dc12-1-455-p.asp

    I drive them from a BOSCH 211 ignition module (lots of clones out there)

    Road test this weekend shows it is all working nicely with the new higher compression squish so dyno next week

    Fuel next. I've started on the throttle bodies. They dont quite fit so need spacers/linkages designing but i've just finished that now.

    Lots of moving bits to play with.....

    Click image for larger version. 

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    Misaligned by 12mmm 1 side and 8mm the other

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    Tricky gearbox I managed to leave alone.

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    Lots of bits to find a home for when it all goes back together!

    SO I have the fly by wire all good with the fail safes built in so nearly there!!

  7. #82
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    .
    Thanks for the coil ignition module info.

    The fly by wire thing is very interesting.

  8. #83
    Got the throttle body bits back today.

    Bit of a jig saw......

    Click image for larger version. 

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    All good and no screws or O rings left on the table!! Although Triumph dont make it easy with tamper proof Torx screws etc.

    Click image for larger version. 

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    The red bits are where I have had to make extension pieces. Some of them are O ring sealed to that had to be mimicked on the extensions. The lever arm on the RHS side also had to have a fancy extension and the LHS butterfly arm had to be extended as well.

    Fired it up and it all works. GT750 fly by wire.

    Just need to work out how to link to the oil pump now (although I am considering going premix after the strip down). If I extend the throttle position sensor linkage I can squeeze a lever arm in for the oil pump.

  9. #84
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    Quote Originally Posted by Kettlekev View Post
    Got the throttle body bits back today. Bit of a jig saw......
    Fired it up and it all works. GT750 fly by wire.
    I think Flettner has his single on Fly by Wire but a Fly by wire big multi cylinder TwoStroke, that might be a first........

  10. #85
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    Quote Originally Posted by Kettlekev View Post
    Thanks, I did see that one but I think it is for a different injector type. Mine come from a Tiger 1200 and the only number on it is GG12. Will keep digging.

    Just for fun I have been trying to understand injector maths....I am sure there is a simpler way to do this and I am probably missing something major but with the end goal to define when to stop injection at the various rev numbers, I came up with a auto calculating excel sheet. I cant seem to attach it? but here is a screen shot.

    Caveats are;
    1. I dont have definitive injector specs yet
    2. I am not sure of the required fuel number (see comment)

    Anyway I am sure someone will correct or it may actually be a useful exercise??

    Attachment 348226

    If anyone is interested I can email it unless there is another way to attach?

    Drop me a pm, I would like to have a copy of this

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