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  1. #1
    Tincorus Maximus
    Join Date
    May 2010
    Location
    Raton, NM
    Posts
    13

    Ignition Advance Curve for Seadoo 787

    Hello All- I have been riding my Microsquirt fuel injected 97 GSX for over a year now, and finally have a lot of it tuned just where I want it. Up to now, I have been running the Micrsquirt in a "fuel only" mode, meaning I let the original MPEM control the ignition, and have had the Microsquirt running the fuel. Now I want to make the leap, and have the Microsquirt run it all. To get started, I was looking for info on what the spark advance curve looks like for a 787. I tried to find some numbers, but to no avail, other than reading about how the MPEM locks the timing to a single amount between 3000 and 4000rpm. Does anyone have REAL numbers or graphs showing the advance curve for a 787? Can be for a carb or RFI engine. Can be the full curve, or even partial info. Any info you have would be really great! Some details on my current system: Running a carb'd 787 with an RFI intake manifold, throttle body and air box. All RFI sensors, except water temperature, which is a GM sensor. Fuel injectors are Chrysler FFV (flex fuel) stainless steel bodies (43#/hr @ 55psi). Injectors are mounted in a modified RFI intake manifold, so that it injects pre-mixed fuel (40:1) right at the rotary valve. GSX RFI fuel tank, pump, and regulator (which are Jeep and Saturn automotive parts, BTW). Engine runs very well with this setup, and I was able to turn almost 200 more RPM than I was ever able to on the modified carbs I was running before. Starts right up in any weather, much like you would expect any fuel injected car to do. I tune at the garage with a laptop, and on the lake with an old Palm Vx PDA in an OtterBox waterproof case. System works very well, and while I consider it an science experiment, everything is wired up and installed so neatly, it looks nearly OEM. I will try to post up some pics as soon as I can get them formatted and hosted. Would REALLY love to hear from anyone else who has used Microsquirt or Megasquirt on their boat or PWC!


  2. #2
    This is how I run a jetski shop in the desert nmpeter's Avatar
    Join Date
    May 2008
    Location
    Elephant Butte New Mexico
    Posts
    6,530
    +1
    1,281
    this megaquirt looks pretty interesting..ever run this thing at the butte?..could be an interesting candidate to run in my test tank. I seem to recall some timing stuff in an old seaddoo race manual..I'll have to dig around , but if I come up with something....

  3. #3
    Tincorus Maximus
    Join Date
    May 2010
    Location
    Raton, NM
    Posts
    13
    No, I only run up in Trinidad, CO and Ute Lake in Logan, NM. If you could take a look around, I would appreciate it!

  4. #4
    Tincorus Maximus
    Join Date
    May 2010
    Location
    Raton, NM
    Posts
    13
    Pete-
    Were you able to find anything? I am pressing ahead with more projects to do with it, but have hit a snag. I know for sure it is ignition related. RPM is generally limiter to somewhere between 4600-4800rpm, and there needs to be minimal load to get to that. If I give it more than about 1/3 throttle, it sputters and dies (load increases, and it acts like it cannot get enough spark to get the mixture lit off). All of the monitoring says the EFI is doing its job. Also, after long periods of holding it at the 46-4800rpm range, and letting off, it has trouble getting back up there, and the ignition breaks up badly. Changing the fueling does nothing to change this condition (although I can make it run worse by going to rich or lean) Mind you, this worked perfectly last season, and I could pull 6950 at Ute Lake (3700'). I am guessing that the coil or spark plug wires are going bad. Changing the plugs did nothing.

    Have you ever wired an MPEM completely out of one of these boats? I would like to retain the info center gauge and the VTS, but I have no need for DESS, and the MPEM is otherwise dead weight and a power sucker. From studying the wiring diagrams, it appears that all the MPEM does is pass the signals from all the sensors through to the gauge. Even the wire colors line up.

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