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Thread: Suzuki GT750 EFI Special

  1. #61
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street Triple R/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
    Posts
    18,345
    Oh well. Try blowing air through an open hole inlet size with a small dribble of oil on the floor (as it only dribbles tiny amounts of oil at low pressure into the inlet) - aimed at a piece of paper and see that you are happy it atomises and sprays.

    I know where my money would go to the result.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  2. #62
    Yep I hear you. No one said this would be easy.

    I'm going to get a baseline dyno with injectors in the throttle bodies first and see how that fares.

    I may need to run two injectors (one small one in the throttles) just to get that return oil mixed and back in around the bores.

    I t will be interstinmg to see what the crank pressure is and just how much squirt it generates. I am going to add a MAP sensor anyway so at least I can measure it.

    My secondary worry with the crank case injectors is contamination......

  3. #63
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street Triple R/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    18,345
    Heck yes, more things I didn't think of. Pull your engine down and it will likely contain a desert-spoon of oil at the lowest point of the crankcase (ok well usually not on small race engines) . The injector there would be soaking in oil.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  4. #64
    Join Date
    18th May 2007 - 20:23
    Bike
    RG50 and 76 Suzuki GP125 Buckets
    Location
    Auckland
    Posts
    10,081
    .
    Cant say for sure as I have not tried it. But the fuel stream from an injector is pretty powerful. I expect it would blast up through a puddle of oil at the bottom of the crankcase.

  5. #65
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street Triple R/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    But the next time you started it, let's say 5 weeks, then what?
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  6. #66
    The position I have them they wont be in the oil puddle at the bottom. They are quite a bit above it.

    So the only real worry is the lack of oil on the inlets and just how much that return oil feed is needed to lubricate the barrels.

    Anywhere I put the injectors will have the same oiling problem (other than on the throttle bodies).........

  7. #67
    This week has mostly been sorting out the Speeduino ignition system.

    Lessons learned;

    RF noise gets in everywhere and generates sync loss, especially when everything is closely packed.

    Use screened cables on the ignition trigger module and earth both ends of the cable.

    Use resistor (5k) plug caps and carbon resistive (not copper wire) core cables

    My little VR crank sensor and the trigger wheel work great submerged in the oil bath. Use screened cable there as well.

    RF ferrites help when power and triggers lines are passed through them (wrap cable round a couple of times).

    At the moment I am running 3 ohm coils with a dwell time of 3ms (running). I am not sure f this is optimum but I have found a good dwell calculator (attached) to test my setup and work out best dwell and then speeduino can control dwell based on voltage. This should avoid any burnouts. I may try to switch to a high performance coil but will review after the dyno run with the new high compression heads.

    Dwell Calculator B&G.zip

  8. #68

    Cool

    Quick update

    The standard 3 ohm coils wont cut it, I run into an Ohms law limitation and the dwell in effect limits out and cant really be controlled via Speeduino.

    So I am going to switch to 0.5 ohm Dynatek DC3 coils.
    Click image for larger version. 

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    They will charge faster, give better spark and will allow the dwell control to work.

    I am using a Bosch 211 ignition module which should handle the power.

    New high compression heads back next week so we will see.

  9. #69
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street Triple R/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    18,345
    I've seen a lot of ignition faults corrected by swapping the fancy looking car type HT lead back to copper wire. Car coils are usually much bigger than bike ones so have energy to burn, or at least waste.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  10. #70
    Join Date
    3rd February 2004 - 08:11
    Bike
    1982 Suzuki GS1100GK, 2008 KLR650
    Location
    Wallaceville, Upper hutt
    Posts
    4,527
    Quote Originally Posted by F5 Dave View Post
    I've seen a lot of ignition faults corrected by swapping the fancy looking car type HT lead back to copper wire. Car coils are usually much bigger than bike ones so have energy to burn, or at least waste.

    Copper HT leads were one of the causes of electrical noise on this project and were replaced for this reason.
    it's not a bad thing till you throw a KLR into the mix.
    those cheap ass bitches can do anything with ductape.
    (PostalDave on ADVrider)

  11. #71
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street Triple R/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    18,345
    Resistor plugs and caps are usually enough along with careful routing of wires so you are not inducing spikes from outputs to the ignition system with reasonable separation of the module from the angry end of the bike it should be fine.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  12. #72
    Question about dwell time.

    My ECU has programmable dwell and my low ohm coils (0.5 ohm) will allow me to run large dwells (current).

    At the moment my start point is 3ms running (4.5 cranking). Clearly I can mess with the dwell until I get mis-fire then back it off but I wondered if anyone else had any 2 stroke dwell recommendations as a starter???

  13. #73
    Join Date
    19th June 2011 - 00:29
    Bike
    KR-1S, KR1-SV, KXR500, ZXR 4/600
    Location
    Belgium
    Posts
    219
    ain't those coils for a CDI ignition ? CDI's do not use dwell.
    such a low resistance can act like a short-circuit in a TCI system. they did in the AEPL-ignition I'm trying out.

  14. #74
    When I run the dwell/coil calculator in post #67 it all works out right.

    Dynatek reference the coils as for use with dwell control ECU's.

    They are low resistance but as far as I am aware its the inductance and coil layout that's key to making the dwell work with Speeduino.

    I agree CDI coils are also low ohm normally but they rely on a positive charge from the ECU via a single wired primary (other side to earth). Dwell coils are two wire primary, one side to 12v and the other earthing/controlled from the ECU.

    That's as far as I know. Testing this weekend with new heads so will let you know.

  15. #75
    Quick update.

    New 0.5 ohm coils and the Bosch 211 trigger all worked out OK with Speeduino

    My current settings are below. My initial voltage compensation curve assumes centers around 13v's but when fully running I will tweak that.

    Click image for larger version. 

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    The dwell/spark settings are all from the calculator I posted earlier so will probably need tweaking on the dyno.

    So far I am impressed with the Dynatek coils.

    I've still got some high rev ignition noise causing the odd sync loss so that is this weekends project.

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