The XJ (Microsquirt) EFI discussion thread

yes BUT how are you going to fish them out and separate them so you can twist each pair individually? May as well just remove the one as it's the same or less effort.

 

They'd probably work, but a set of throttle bodies off of a modern 4-cylinder transverse FI bike would be easier and cheaper. I think I've heard that the GSXR 600 throttle bodies will fit, and sets can usually be bought reasonably on eBay with injectors included.

For instance, here's a set with injectors and fuel rail for $75: http://cgi.ebay.com/ebaymotors/2006-06- ... 3a6a6cd009

The one thing I couldn't figure out how to do with those types of setups is idle control. I wanted a solution where I would always have correct idle and could start the engine under any circumstances without having to crack or hold the throttle or use a "choke." Some factory FI bikes use a "choke" (that's what it says on the lever) to open the butterflies a bit extra when the bike is cold. I think some of the ITB systems use an ECU controlled solenoid for the same purpose.

Long story short, it may have been easier to convert to FI if I'd used a set of ITB's off an FI bike, and it probably would have resulted in some extra power at higher RPM's that I may be missing now (not that I think the bike is at all underpowered), but it would probably have been a lot harder to get the type of idle control I wanted (and now have). Also, OTOH, the larger air space in my current manifold may make for some better low-end power than I would have seen with ITB's.....

 

The pickups have their own harness, so I would just cut the plug off and remove the outer insulation. 5 minute job. The plug would be replaced with a sealed connector as part of the job anyway.

 

On mine, yes, they had their own wire bundle, separate from the main harness, but they shared a single ground wire back to the TCI; so making twisted pairs for them would actually have required replacing the wiring so that each pickup had its own ground wire.

 

I am currently working out an advance table for my system, and have already learned a few things.

To duplicate the factory advance curve seems very simple, as the XJ750 has a straight forward method of advance. Timing starts at 10 degrees and advances with RPM to a maximum of 36 degrees at 5,500 RPM according to the manual.

However the Microsquirt will have a MAP sensor, which now allows me to program for different amounts of load. Research finds an XJ1100 that uses vacuum advance as well as the RPM. The XJ1100 shows no difference in advance at high load (wide open throttle), but a lot more advance between 1,000 - 3,500 RPM at light throttle. With the full load advance being almost identical to the 750, this is changes I am happy to use as a guideline for making an advance map.

I would expect better low speed low load throttle response with this addition to the bike.

Research, learning and then application... fun times

 

I suspected there were only three wires for the two pickups but was too lazy to look at my wiring diagram

 

How do you add a return hose back to the tank for the regulator?

 

I used 1/4" copper plate and brass plumbing barb fittings to make fittings for the tank.

On the left side I made an oval base plate and soldered half a barb fitting into it to make a tap that mounted in place of the original fuel cock.

On the right side I soldered together a brass barb with an NPT threaded end with another half of a barb fitting to make a panel mount double barb. I then used another piece of copper plate and an NPT tap to make a nut for the fitting. I attached the inner part of the double barb to the in-tank fuel pump's outlet, and fed the other end of the barb out a new hole I drilled in the right side of the tank. I then used a washer, some fuel-proof gasket paste, and the copper nut to fasten the fitting in place.

By the way, some systems use a regulator in the pump to provide reasonable pressures at the injectors without a return line. What I don't know is how these systems ensure correct fuel delivery when the rail pressure to manifold pressure is not a constant difference. I would guess that Megasquirt allows some option to adjust the injector pulse width based on the instant MAP reading, but I have never seen (nor really looked for) this setting.

 

Wow this is really interesting stuff, thanks for starting the thread and thanks also for the links.

I've done some reading and have a lot more to do, this is really grabbing my attention!

SQLGuy, you mentioned throttle bodies/injectors off a GSXR...dumb question here but would they need to come from a comparably sized engine? Such as from a 600cc to a XJ650?

 

Pretty much. The main factors are diameter of the throttle bodies, and spacing (if they're not separable/adjustable). Typically throttle body OD is going to be pretty similar to carburetor OD on similar sized engines.

If you're doing more fab work, like in the area of the pieces that mount the throttle bodies to the head, then you can get away with more mismatch in the diameter. I would still expect the best results to be from arrangements that provide a close match in ID of the throttle body to ID of the intake port.

 

Okay I see...I may have to start looking for a crappy (cheap) bike and start playing with this. Thanks much!

 

Just re-posting this from your original thread.

Also I had found a GSXR 600 rail that would work find off only 2mm.

Just an FYI to this thread, the Micro Module is available but with the 50 pin header to wire in and alternative comm and JP2 to wire in if used, is a lot of soldering and work. Plus you should have some experience with this kind of thing. Reading as much with the micro tune system is a huge plus to know before hand. Read as much about this system will help you with other EFI systems which are all basically the same running off the typical lm1949 microprocessors. I didn't spend more than $700 for pump, regulator, injectors (only running two independently), WBO2, Micro module, MAP, GM IAT, TPS and a Buell MAF. I also played around with the GSXR Hi-Z injectors that I got at a local salvage for $30. each.
I used the existing ignition pick up and trigger which works fine. You can utilize the wasted spark method quite easily. Isolation from RF noise is a must and there is many methods you can find on line to reduce from particularly the coils. I even used copper tubing, grounded, to run wires through.
Alternatively there are many simplified circuits available that can be built that are called Alpha N controlled. Meaning TPS and O2 are the main control factors and runs in basically an open loop mode. Most early EFI systems were this way. Once your read more about this stuff you'll realize a good working system can be built between $500 to $1000. Depends on where you find sensors, your capability to build hard components, understand electronics and have experience assembling basic circuits involving micro processors. Some have made Alpha N using the Arduino processors.
Learning this stuff may seem daunting but like anything else, once you start to understand the basics the rest is easier to learn.
I've posted in here I have a home turbo mod on my little 550 and used the miro squirt module.
Excellent job on the 750 btw. Nice work.

 

The Mega/Micro squirt systems all use Motorola processors. MC9S12C64, in the case of Microsquirt.

I'm surprised that your project turned out quite that cheaply. My best guess on parts runs like this:

Microsquirt 400
Bosch Pump (new) 90
Copper and brass pipe fittings for manifold, fuel rail, and fuel connections 150
Fuel line 15
Injectors (used) and injector cleaning 110
Throttle body with ISV and TPS (used) 10
Coils (used) 15
Plug wire caps 30
IAT (used) 2
Fuel-proof paint for manifold and fuel rail 8
Throttle cable 12
36-1 wheel (materials) 30
1/4" copper plate (materials) 30
Relays 10
Fuses, wire, electrical tape, and electrical terminals 30
Head temperature sensor (new) 15
Innovate LC-1 WBO2 with gauge 160
Screws, nuts, bolts 25
Air inlet hose 5
Metal plate for rebuild of air box 5
Silicone RTV 8
NCV1124 and other mod parts for Microsquirt VR conditioner circuit 10
Silver solder for manifold and fuel rails 20
Gasket sheeting 5


For a total of $1195, not including shipping, special tools, and things I already had on hand (like the 7mm copper core wire for the new ignition wires). This is all based on the stuff currently on the bike, not the stuff I decided to change after having done it once (or twice) differently before. Hmm... also forget hose clamps and the fuel filter...

OTOH, I did recoup some credit for other XJ parts I needed by trading in my old carbs and TCI.

 

The module I paid for (at the time) was only $250. I'm pretty familier with the MC9S12C64.
The module at that price, did not come with the housing at all or Harness. I made all that. Keep in mind I have a bunch of parts, wire, mill and layth. Basically to include time and energy and parts paid for months or years ago, yea you're right, still probably around a grand or maybe more. Yet out of recent pocket as of this build (only the EFI part) was actually 686.37 including incidental purchases. The filter was given to me, I've had pipe laying around for years in the diameter I needed, etc. The bike modification hard costs itself, was WAY more. If you haven't already you can see the project here.
So are you done with it now? Are you driving it around? Have you put some good miles on it yet?

 

Oh, I've been riding mine for about three years now. The last incarnation (second gen intake and third gen fuel rail) has been in place for about a year. I'd guess I've put about 4000 miles on the bike since converting to Microsquirt.

 

What difference in your mileage did you find, now that you've had some real decent mileage put on it.

 

Can't say, as I never had any good measurement "before".

After, on long trips up in the mountains (a lot of up, and a lot of down, mostly 55MPH+, and between 6000 and 11000 feet elevation), I got between 52 and 56 MPG on three different 150 mile plus trips.

 

Just a heads up and anyone shopping probably knows this.
There is a NEW version of the microsquirt coming out very soon. Inventory is pretty much gone of the old ones I guess so if you tried to buy one you probably couldn't.

The new version is in a much more waterproof case and has some software as well as hardware improvements.
Big difference is they took the coil igniters out of the microsquirt so you either need coils with that function built in or a separate igniter (driver) whatever you wanna call it.
This was mentioned in the first post on this thread and that is for sure the case.

GOOD news>>>The price is going down!
I read in a couple spots it's gonna be $299 for the controller!

I HOPE to start my conversion project this fall but plan on building a small stand to be able to tune and tweak the engine outside of the bike frame and a buddy has an engine dyno so I hope I can simply take it up to him and slap it on the dyno for fine tuning before I even put it in the bike.

 

My 700 got about 45mpg originally. After the 2 carb conversion it dropped to 42 mpg but runs exceptionally well. 52 to 56 mpg is great. Now a fair ballpark figure, how much does it cost to do this conversion?

 

I think it's still gonna be between $750-$1000 depending how creative you get and how lucky you get on Ebay plus your own fabrication abilities.

I would LOVE to strip my carbs and put injectors in there but that's just too damn much work for me. It would be nice to maintain the stock OEM look but have the performance of EFI....but maybe the 2nd time?

I'm planning on buying a throttle body set-up off a EFI bike and adapting that. It will have the TPS, injectors, fuel rail and SHOULD make the conversion a lot easier than SQLGuy project. I THINK the new configuration will make the low end tuning much easier.
He did his a while ago (a pioneer and I hope that there is more stuff available at better pricing than back then.