Author Topic: Megasquirt on a K75. (DIY fuel injection system)  (Read 59571 times)

Offline wmax351

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Megasquirt on a K75. (DIY fuel injection system)
« on: August 31, 2011, 11:03:10 PM »
I've been wondering about upgrading my K75 to a more efficient closed loop EFI system, most likely mega/micro squirt.

It would be partially as an interesting engineering hobby/fidgeting project. But it may be somewhat practical as well. Should allow for a decent bump in mileage, especially at higher speed, where the LE-Jetronic loses accuracy, and as far as I know, utilizes an open loop enrichment trigger, as well as running rich from the start. Would also add in a wideband O2 sensor, which would greatly simplify tuning. 

Also would allow for cheap and less restrictive MAF sensors, or quicker responding MAP sensors.

I've seen megasquirt used on a turbo'd K75.


Not really looking to create a superbike. K75 wound out is plenty fast for me.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline wmax351

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #1 on: September 11, 2011, 05:51:36 PM »
I may have found a source for a cheap, second hand megasquirt from a friend of mine on the UC Berkeley Super Mileage Vehicle Team.

Should greatly reduce the budget needed for this.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline frankenduck

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #2 on: September 12, 2011, 03:32:31 PM »
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline wmax351

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  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #3 on: September 12, 2011, 07:21:05 PM »
In terms of what I would be doing, the two bikes are actually identical. I will be doing batch injection, so all it needs is the RPM signal from the tach and the temperature sensors.

I would just remove the MAF sensor, and put a intake air temp sensor in the plenum. After syncing the TB's by closing the Idle Bypass screws and adjusting the TB's, I would use a vacuum line from the middle cylinder for the MAP sensor. 
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline frankenduck

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  • Posts: 3653
Re: Any thoughts on updating the EFI system on a K75?
« Reply #4 on: September 12, 2011, 08:39:25 PM »
You can pull an RPM signal off of the coils directly.  That's what I use for the cruise control.  I use the outboard wire on the connector.
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline wmax351

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  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #5 on: September 12, 2011, 11:58:00 PM »
You can pull an RPM signal off of the coils directly.  That's what I use for the cruise control.  I use the outboard wire on the connector.

Good idea. Should be an easier splice and a cleaner signal.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline frankenduck

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #6 on: September 13, 2011, 06:49:20 AM »
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline frogy

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  • Posts: 91
2002 R1150RT
1985 K100 Naked

Craig

Offline wmax351

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #8 on: September 13, 2011, 09:35:46 PM »
A couple friends of mine want to megasquirt their 2002's, so I've now got people to split some of the costs, like a wideband O2 sensor and the stimulator.



  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline wmax351

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  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #9 on: December 04, 2011, 09:12:55 PM »
I tracked down the Plug for the Jetronic computer: No need to cut or make a harness!

Free samples are great btw.

http://www.te.com/catalog/bin/TE.Connect?C=17458&M=PPROP&P=10008,2349&BML=&LG=1&PG=1&IDS=96454,170034,169740,169741,169618,169619,96373,169736,169668,169669,383933,383934,383935,383936,383937,385795,487242,169613,169614,385794&N=1


I will be starting on this over winter break. I will make a point of doing a writeup on this.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline frankenduck

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #10 on: December 04, 2011, 09:23:22 PM »
Interesting project.  Keep us posted.

Drop me a line if that connector doesn't work.  I've probably got one lying around from a cut up harness....
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline wmax351

  • ^ Quintessential Motobricker
  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #11 on: December 04, 2011, 09:35:48 PM »
Interesting project.  Keep us posted.

Drop me a line if that connector doesn't work.  I've probably got one lying around from a cut up harness....

Will do.

The part I need is from the ECU, unfortunately. If you have a dead/fried/smashed ECU, that would work well though.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline frankenduck

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  • Posts: 3653
Re: Any thoughts on updating the EFI system on a K75?
« Reply #12 on: December 04, 2011, 09:39:56 PM »
The part I need is from the ECU, unfortunately. If you have a dead/fried/smashed ECU, that would work well though.

I don't have any fried brains but occasionally people have them go bad and buy a replacement from me.  Next time somebody buys one I'll ask about the old one....
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline Chaos

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  • Posts: 2400
  • Mars needs women!
Re: Any thoughts on updating the EFI system on a K75?
« Reply #13 on: December 04, 2011, 10:16:27 PM »


I don't have any fried brains ....

ahh, takes me back to the 70's
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
2012 Ural 2WD sidecar (BMW's bastard step child)

Rick G

  • Guest
Re: Any thoughts on updating the EFI system on a K75?
« Reply #14 on: December 05, 2011, 05:56:26 AM »
I will look forward to a report and writeup as I am building my own version of motronic for my KZ1300 Kawasaki. I know that the later ones came with injection but it's a pet project.

Offline wmax351

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #15 on: December 07, 2011, 04:52:17 PM »
Been working out how to set up the Megasquirt ignition system, which would give me better control of the advance.

I'm going to start with fuel only, then go from there.

The Megasquirt system is not designed to work with the twin hall sensor, 2 window design on our bikes. I need to trick it into thinking it is something different, like 2 timing wheels.

If I set up two logic gates, I can get 3 evenly spaced pulses per crank revolution, as well as 1 pulse per crank revolution to identify a cylinder.

I can set up an AND gate for the 1 pulse, which will come from both of the Hall sensors, and an OR gate which will pulse 3x per revolution.

Not to sure on the exact circuitry, but it seems pretty easy to implement. If anyone is familiar with circuit logic, it would be very helpful.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Rick G

  • Guest
Re: Any thoughts on updating the EFI system on a K75?
« Reply #16 on: December 07, 2011, 08:10:36 PM »
I checked out the Mega Squirt and it certainly seems a better way to go. Getting good info on a Bosch system is like trying to find a unicorn let alone a virgin to ride it.
Disagree Disagree x 1 View List

Offline wmax351

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #17 on: December 07, 2011, 09:37:47 PM »
I checked out the Mega Squirt and it certainly seems a better way to go. Getting good info on a Bosch system is like trying to find a unicorn let alone a virgin to ride it.

Its all about learning how to extract info from the mythic Bosch Elves. :P

A lot of the stuff is all from the same companies. Bosch seems to get ALL of its electronic components from tyco: IE: AMPseal connectors (Fuel injectors). Junior Power Timer (Similar to the one for the L-Jet connector, but much smaller) are for other connections. IE: the ones on the TPS.



  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline wmax351

  • ^ Quintessential Motobricker
  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #18 on: December 07, 2011, 11:02:39 PM »




Seems like this guy (who made the turbo K75) made his own trigger wheel with optical sensors. Its a 15 tooth wheel, with a 1 tooth wheel underneath. the one tooth (deeper cut) wheel triggers both sensors, and the other windows only trigger one sensor. From that, megasquirt can interpret the two sensors, with the deep cut coinciding with a specific crank position, syncing the shallow cut sensor, which then counts the windows, in order to trigger the ignition.

I could definitely do this: I have access to a CNC shop at Berkeley.

I sent him a message, I will see if he sends me some more info on the project.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline wmax351

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  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #19 on: December 08, 2011, 06:24:38 PM »
With some more thinking and suggestions from a guy who turbo'd a streamliner K75 to 203mph at bonneville, I think I will just leave the ignition as-is. The bosch system is very good, and in his case worked to 12,500 rpm with a slight modification.

So right now I am looking at the following setup:

Stock:

-Coolant Temp Sensor
-Igniton System
-Injectors
-Fuel delivery system


New:

-Fan Control (Maybe). I could even set the fan to run for a minute after the bike has been running for 10. Would prevent any sort of fan seizure issues
-Fuel Control System
-Oxygen sensor (Narrowband for now, I'm to cheap to do a wideband system. Although this looks promising in its cheapness: http://www.waltech.com/site/index.php/open-source-projects )
-Potential addition of a multi-function display: Fuel+ on steroids. Can do MPG, Estimated to empty, Temp, AFR, etc
-Manifold Absolute Pressure Sensor: (2x built into the MS system: one for automatic, constant barometric correction, the other for throttle body vacuum signal)
-Intake Air Temperature sensor: will use a GM coolant temp sensor, works the same, but with better durability, and sufficient response time for a naturally aspirated engine.
-Throttle Position Sensor (rather than an idle switch): I am using a cheap one off a hyundai: same fitment as one off of a volvo 850
-I may add an automatic fast idle stepper motor, to replace the fast idle cable. I figure I can do something more useful with the choke knob than to run the fast idle.


Will Remove:
-L-Jet System
-MAF sensor (I will keep it in a box, with everything needed to return to normal, L-jet system, ready to be overnighted if need be)
-Idle Switch

  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline wmax351

  • ^ Quintessential Motobricker
  • Posts: 1218
Re: Any thoughts on updating the EFI system on a K75?
« Reply #20 on: December 18, 2011, 08:23:22 PM »
I'm figuring i should abandon this project. More work than i need, and will cost more than its worth for me. i will put the money towards a new rear shock.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline HCorn

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  • Posts: 91
Re: Any thoughts on updating the EFI system on a K75?
« Reply #21 on: December 19, 2011, 07:05:23 PM »
But then how will we wrench vicariously through you?
1986 K75T

Offline flatlandflyer

  • Curious
  • Posts: 4
Re: Any thoughts on updating the EFI system on a K75?
« Reply #22 on: December 21, 2011, 10:42:16 AM »
Damn, I'm sorry your giving up on this,I've put a Squirt on 2 engines now, am tickled with the first( a MS2,runs a Mazda 2.2 12 valve 4 banger,was turboed with a VJ11 IHI, and intercooler,broke a piston  @ 14 psi so I rebuilt, pulled the turbo & am running it N/A now.Delivers 23 MPG on a regular basis as my daily and has shown me 30 .Starts @ -10 with ease.) The second is a MS3 plus 3X full seq. with 8 Chevy LS coils and ITB's on a small block 383 chevy.Throttle response on this is great, but is in a C3 Corvette ,brakes are screwed up again ,Just pissed with the pile.Plan to get back after it in a month or so.
   Wondered how you planned to tune,I did both of mine on lonely highways here in Ne.Is easy with a lap top setting on pass. lap.I don't think that works very well on a scooter.
  I've a stim if you change your mind.
              Gimpy

Offline wmax351

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Re: Any thoughts on updating the EFI system on a K75?
« Reply #23 on: December 21, 2011, 03:42:20 PM »
I was going to strap a netbook to the back seat, and run autotune with a wideband o2 sensor.
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline flatlandflyer

  • Curious
  • Posts: 4
Re: Any thoughts on updating the EFI system on a K75?
« Reply #24 on: December 26, 2011, 08:34:03 PM »
Sorry for the late reply,(had to make the chubby fella in the red suit happy)That would work if you get the tune close,Auto tune just puts fine touches on.I would like to get rid of the air flow meter, and add closed loop/O2 sensor to the K100 also. I wondered if the Motronic from an 1100 would be close enough to run the 1000.If I read correctly this system is a speed /density setup, is that correct?
        Gimpy

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