I have a feeling I'm going to start a project that I should have never thought of doing...
I am tired of carburetors and I want fuel injection. I know there are a few of you that have gone though (or are going through) the project of installing an EFI system. I have seen microsquirt mentioned a couple times, so I went to their website to research what I would need to acquire to make this happen. The microsquirt (from my understanding) has 2 spark outputs with a possibility of 4, but only has 2 fuel outputs. It seems as though I would need a 4 spark outputs, 1 for each spark plug and a 4 fuel outputs, 1 for each cylinder.
I guess the question here is, will the microsquirt only work on a twin or is there a way to program the microsquirt to spray at different times in all 4 cylinders?
That's what concerns me. It appears that the microsquirt only has 2 fuel outputs, so I'd have to go megasquirt.
From what I can find, batch injection should work well enough on a 4-cylinder. It sounds like the only way sequential would be better is if you tune each cylinder individually. But you need a ton of sensors (individual EGT and O2 per cylinder) and dyno time to be able to see that benefit. It seems like you'd be fine with a simple tune using a single O2 sensor.
The microsquirt (from my understanding) has 2 spark outputs with a possibility of 4, but only has 2 fuel outputs. It seems as though I would need a 4 spark outputs, 1 for each spark plug and a 4 fuel outputs, 1 for each cylinder.
Technically, you don't even need to touch your ignition system. If the factory stock ignition is working fine, leave it alone. You're trying to replace the fuel system. They are separate with carbs, and can stay separate with EFI. But you will need to figure out how to get the crank trigger signal into the microsquirt (or whatever ECU you use). You can always go back and add the ECU controlled ignition later once you get the fuel system working.
As for fuel, it looks like the microsquire can do the job. But you'll need a lot of other parts.
What would you use for the throttle body and injectors? The most direct fit solution would be to get a set of throttle bodies from a GPz750 Turbo or a GPz1100. The cylinder spacing is correct, the assembly includes injectors, and some of them have a throttle position sensor that may be useful or at least could be adapted to work. But watch out for the early GPz1100 throttle bodies. Those bikes had injector ports cast into the head and would be pretty useless for your use.
Do you have fabrication skills. You could fabricate a manifold and plenum and get an automotive style single throttle body. But making the injector ports would be some real work. Certainly more complex than the tubes and boxes part of the manifold. I suppose if you have a common plenum you could do throttle-body mounted injectors...
Next you need a fuel pump, fuel pressure regulator, some plumbing to get the fuel to return to the tank, and wiring for the pump.
And you'll need to weld a bung in the exhaust for the O2 sensor, and figure out how that's all wired. Also, the throttle position sensor on the early GPz bikes was a bit crude. You might need to adapt a modern one to the TPS mounting location.
Another reason why you might actually want to use batch fuel injection is that I believe sequential injection requires that you add a cam shaft position sensor. The crank sensor isn't enough. With the crank sensor alone the computer doesn't know which stroke the cylinder is on. All the crank sensor tells the computer is the location of top dead center, but it could be the compression stroke or the exhaust stroke. The cam sensor allows the computer to know when to fire the injector. Adding a cam position sensor is not easy. I think you'd have to fabricate a sensor mount on the cam cover and figure out how to attached a wheel or magnet to the camshaft.
What else? I think you also want an engine temperature sensor. The injected GPz bikes had a mounting point in the cylinder block for a temperature sensor.
Then it come to tuning. I've heard that short individual throttle bodies make it very hard to get a good signal for manifold pressure (MAP). It's also tricky to use an air-flow meter (MAF), as you'd need four of them, or one on the air box? I think that often leaves just Alpha-N fueling. Alpha-N is kind of a best guess for how much fuel is needed, based on only throttle position and engine speed. But it doesn't really adapt to load (up hill or down hill) or atmospheric changes (temp, humidity, pressure). I believe this is essentially how the GPz110 unitrack was set up, so it can work, but lots of folks replaced the EFI with carbs on those bikes.
I've wanted to do the EFI conversion for a long time. But it seems like a TON of work so I've never done it. Maybe someday.
I think you will find that a Megasquirt ECU is physically too big to be hidden on the bike somewhere (unless you have hard saddle bags or a larger fairing) they are designed for cars.
The Microsquirt ECU fits perfectly under the standard battery box (got mine bolted there) it is about the size of the average wallet. The AMP seal plug dwarfs it, the Megasquirt is considerably larger and is designed to fit in a glove box or trunk.
These engines are pretty primitive by todays car engine standards so sequential injection is way overkill. Maybe concentrate on using some smarter coils and a spark controller.
I am using a DIYautotune Quadspark controller and some DYNA mini coils. I am going to control my ignition with a toothed wheel and a hall sensor. Coil selection is critical, they can't draw too many amps of the stator will not be powerful enough to charge the battery. This is also true about the fuel pump, too much draw will kill the battery. That is why ditching the stock ignition (Dyna S) will save the stator in the long run.
I have GZP1100 throttle bodies and was able to make a stock LS7 TPS fit under the end cover.
I was able to fit all the wiring under the stock side covers on a KZ650 chassis. Motor is a GPZ750 top end on a KZ650 bottom end.
I have been spending all my time at work (thank God I'm in management!) trying to piece together and price out the cost of doing this. I had been planning on manufacturing (by hand) a plenum to carry the injectors and a single O2 sensor. Most of the machining I have done in the past 20 years has been CNC and I no longer have those machines at my disposal. It will be much more difficult machining it by hand, but I am confident (enough) in my capabilities to at least give it a shot. I will need to find a throttle body that would work and figure out the TPS.
I know there are still quite a few details to iron out and I'm hoping I can get this all figured out in a couple months so I can get started on it this winter. If not, there's always the winter after!
I had a set of GSXR600 throttle bodies re racked and a new fuel rail made to fit an old CB 750 honda, I also had the 750 style throttle cable linkage added so I could use stock cables, much better than the old 80's stuff..
I made my own throttle bodies out of billet 6061 in 1995 for my drag bike (mechanical fuel injection) at that time you could buy off the shelf throttle blades (Hilborn) at a reasonable cost. Trying to machine the throttle blades would have been very tricky so we just picked a size and bought a set. If I would have known the GPZ1100 throttle bodies were as good as they were I would have used those instead of making them. The cast Hilbron motorcycle throttle bodies available back then were brutal, full of inclusions. The GPZ throttle body casting is exceptional, at least the one I have is.
I had been planning on manufacturing (by hand) a plenum to carry the injectors and a single O2 sensor.
I will need to find a throttle body that would work and figure out the TPS.
A custom intake manifold with runners and a plenum would be really cool, but a ton of work. I'm not sure where you would fit the throttle body. Maybe if you removed the battery box it could go there? If you used a single throttle body, you could also use a MAF sensor and get very good load data for the ECU. If you could fit it all in it would probably run great.
Plus it would be very easy to add a turbo later.
But if it were me I would just use the GPz1100 TB set.