Megasquirt :)

Discussion in 'Airheads' started by awaffa2003, Aug 10, 2012.

  1. awaffa2003

    awaffa2003 Adventurer

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    So I'm starting to get a list together of all the items I'll need to fuel inject my bike. I have a pair of throttle bodies from an RT an a pair of fuel injectors, I had an O2 sensor bung welded into my header crossover, and all i need now is the Megasquirt parts, board, and case. Now the questions, do I need the sensor that was attached to one of the throttle bodies? I imagine it was a throttle position sensor and if so...do I need it for my application?
    #1
  2. Airhead Wrangler

    Airhead Wrangler Long timer

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    I know ZERO about fuel injecting airheads, and relatively little about fuel injection in general, but you'll also need some kind of mass flow sensor in the intake, won't you? (in addition to the TPS)
    #2
  3. naginalf

    naginalf Handy Schtroumpf

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    Ah. Now here I can be of some help. I was thinking of doing this as well, but thought I'd leave well enough alone, however, it would be nice to have a redundant setup using the carbs as throttle bodies, but there doesn't seem to be enough room for the injector behind the throttle plate. Thought about using this little guy:
    [​IMG]

    DIY autotune is a very good resource btw. I had done most of the research I needed for this mod when planning to fuel inject my old honda, people had very good success with it. But is there anyone who's already done this to these bikes? You might do some research on the megasquirt forums and find all your maps already made :D.

    To answer your question, yes that was a throttle position sensor, you'll be needing that trust me (although, you can get away without it, the pressure sensor can cover most if not all instances, the TPS just tells the pooter when you've got it hammered and is a little more precise when throttle is further open). In fact, you can do some super simple but very effective fuel maps with just the throttle position. You actually don't need the o2 sensor once you have your maps made up, but it's good to have some wiggle room for the o2 to adjust. The problem is that unless you go with a lamda sensor, it's not a very accurate affair, it basically bounces around between rich and lean and doesn't do much else. Wrangler is correct tho, you may want some sort of air flow/pressure sensor. Most 'squirters just use an air pressure sensor, usually the barometric correction type, that along with your throttle sensor is more than enough throttle/air input. Oh and you need an intake air temp sensor and it's preferable to have an engine temp sensor. With air cooled motors, you don't want to use an oil temp sensor because it heats up too quickly, usually people find a way to mount a cylinder head temp sensor to the back of the head between fins.

    However, for a super simple FI, all you really need is a throttle position sensor, an intake and cylinder temp sensor, and some sort of RPM trigger. The rest is icing for smoothness (air sensors), power (the full gamut of sensors), and economy (o2 sensor).

    You're also gonna want to install a trigger wheel somewhere, probably on the timing chain crank sprocket. It's not necessary per se, you can use the stock ignition trigger, but then it is much harder to play around with spark advance and whatnot (actually, I think you are forced to use the stock ignition). Plus you can replace the stock ignition all together, while leaving it in place for a backup.

    I wouldn't do a megasquirt tho, it's not sealed. Get a microsquirt, it's all sealed up waterproof, made for bikes, small, and has everything you need built in.

    As for the O2 sensor, I was considering adding one simply for tuning the carbs, but I got to thinking about it this morning and was wondering where to put the sensor and wire up the heater, then I realized that there is the perfect bung already installed on the bike where the secondary air system went. I wonder if there's any o2 sensor that will fit there? Plus, then you don't need the heater (2 wire type as opposed to 3/4 wire type).
    #3
  4. naginalf

    naginalf Handy Schtroumpf

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    Your next biggest problem is going to be installing the fuel pressure system. You CANNOT get away with simply using the petcocks for fuel delivery to the pump. It is a much more complicated system than you think, do some research on how the fuel pump and pressure regulator works, that is key.

    Your best bet is to customize your tank to fit an all in one unit like the suzukis use. It has the pump, pressure regulator and filter all in one unit. Or you can install a vent tube for the regulator to vent into. With these bike however, you could use one petcock for fuel delivery and remove the other and install a vent tube in its place. You can't use the fuel cap's vent because you still need that to let air in when it uses gas of course.

    Sorry for the long winded replies, I'm just so excited to see someone else considering this. Subscribed!:lurk
    #4
  5. ignatz72

    ignatz72 call me iggy

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    :eek1

    But I'm just as happy following the FI progress, neat project!
    #5
  6. disston

    disston ShadeTreeExpert

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    Ha Ha Ha...But I do hope it works.

    Yes you need a fuel pump. FI usually uses 100 psi or close to it. And a return line too, so the gas tank gets really hot.

    The system using a Mass Air Flow (MAF) is usually considered the best but it can be done with out that. I forget what it's called but relies on more computer data and less real time data.

    A manifold Air Pressure Sensor and a Barometric Air Pressure Sensor. Sometimes one sensor can do both of these.

    What you really need is a kit isn't it? Or can you write the program for this yourself.

    Please tell us more.
    #6
  7. Airhead Wrangler

    Airhead Wrangler Long timer

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    ...as well as a charging system that can support a fuel pump.
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  8. naginalf

    naginalf Handy Schtroumpf

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    +1 definitely, this was the biggest problem on the old hondas, unlike these bikes the hondas had no aftermarket electrical system upgrade, you had what you had, you could make it beefier but not more output. We were skimping on everything we could, especially lights. Did you know that even only a few incandescent gauge lights take as much as 35W? But the 400W alternator upgrade would be ESSENTIAL for this project without having to skimp on the lights and such. Although you can shave a whole lot of power by going LED on everything you can and using an HID on the headlight (HID uses 35W vs 55 for a halogen).

    I love this idea, but I must say, the carbs on these bikes are so simple and easy to work on and get to. My honda was a PITA with 4 in a row literally stuffed behind the motor. Here you're replacing a simple, easy system with a complicated electronic system that takes a lot of custom programming, all for negligible gains. But if it's a project yer dedicated to, go for it. Make sure you're really dedicated because it's a lot of work to get it right and it could really hurt your bike (or yourself) when doing so.
    #8
  9. RGregor

    RGregor Been here awhile

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    Hi!

    If you can read german search www.2-ventiler.de for "Ohne Vergaser"
    User Euklid55 has successfully done the conversion using the ignitech injection module.
    Good luck to your project.

    Best regards, Rudi
    #9
  10. wmax351

    wmax351 Been here awhile

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    I'm planning to megasquirt my K75. Much less ambitious undertaking.


    In regard to the fuel pump, you could use a low power fuel pump, like one for a scooter or small motorcycle.

    http://delphi.com/manufacturers/other/powertrain/t11/

    You would only need maybe 4 gallons/ hr for an airhead. 100 hp requires about 7 gallons/hr. Pairing this with a fuel reservoir might work.
    #10
  11. Prutser

    Prutser Long timer

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    #11
  12. disston

    disston ShadeTreeExpert

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    The fuel requirement is not only a matter of the volume or amount of fuel but the pressure feeding the injectors. They need a certain amount of fuel pressure to work. That smaller fuel pump may be suitable but I am puzzled by their omission of data relateingf to fuel pressure. You can have all the volume you want, just use a larger tube.
    #12
  13. naginalf

    naginalf Handy Schtroumpf

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    DIYautotune has this walbro unit for $100:
    [​IMG]
    But that's just a aftermarket car part replacement, they make fuel pump replacement parts for almost any car but they're made in china by the millions. Here's an MSD Ignition unit for the same price, I'd trust it a little more, at least you'd actually get service on the warranty (diy makes no mention of one, contacting walbro would prolly be a laugh). Plus, as you can see, it's more of a universal fit and mounting affair, with the attachment hardware and barbed ends included.
    [​IMG]
    #13
  14. Beater

    Beater The Bavarian Butcher

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    Very interesting project. 21st century technology attack on stone age technology. I like it.

    :lurk
    #14
  15. US_Marshall

    US_Marshall Adventurer

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    Your fuel pressure is dependent on the injectors your using. Some of the smaller side port injector (used in TBI) operate on 13 psi. A MAP sensor and IAC valve can be located in the air box with a cross over tube between cylinder.
    #15
  16. Kai Ju

    Kai Ju Long timer

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    Take a look at Honda's TRX420/500/680 fuel injection systems.
    Throttle body with combination TPS/MAP/Baro sensor, external fuel pump that puts out 50 psi and is contained within an aluminum housing which is gravity fed from the fuel tank.

    http://tinyurl.com/8d2f4kb

    http://tinyurl.com/8j88ncr

    I don't remember what the bore size is but it's feeding a 420-680 single cylinder four stroke.
    Who knows, there should be plenty that have been totalled ..............
    That should take care of the hardware.
    #16
  17. toplessFC3Sman

    toplessFC3Sman Adventurer

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    Shameless plug, but here it is anyway:
    http://advrider.com/forums/showthread.php?t=515691

    There is a lot to consider, but the biggest IMO is the power required. Most non-FI bikes have alternators around 60 - 80 watts, which is enough to power the head & tail lights... and thats about it. A higher-pressure fuel pump will easily draw 60+ watts, injectors & coils will be another 40ish, then you still have all the lights & need to charge the battery, so you're looking at needing to at least double the capacity. Modern FI bikes have 300+ watt alternators, for reference (more for touring bikes).

    Then, as mentioned, there's the fuel system, where you'll need to package the pump either in the tank or externally, but either way you're flowing much more fuel than most of the petcocks could manage, especially considering that any external fuel pumps you find will have much, much more flow than you'll need. That Walbro pump (255lph) can flow enough fuel to supply a 350 hp car running rich, all that extra flow for a 50hp bike will just be sucking more current (for this one, maybe 120watts), requiring you to have a much beefier charging system. Walbro makes a 150 lph pump that I'm using, but even that is way oversized. (I also have one of the 255lph pumps in my project car, and it's been problem-free for 30k miles & 5+ years for what its worth)

    Also, I hope you like wiring, cause you'll need to create a harness out of scratch for all the additional sensors & controls of the MS system. I got one from a wrecked CBR F4i since I was using a number of other components from it, so all the connectors would be there (which can be some of the more difficult parts to find).

    Its a really fun project, but make sure that you know what you're getting into, and have the ability to do some fabrication work when it's needed. Good luck! :thumb
    #17
  18. awaffa2003

    awaffa2003 Adventurer

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    I've got the microsquirt module, but I'm still looking for a BMW TPS that came on the 1150 throttle body....and the plug.
    #18
  19. awaffa2003

    awaffa2003 Adventurer

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    Ahh and I went with microsquirt, more compact :)
    #19