M-unit and ignitor ?

[skunkworks]

hey guys how ya doin?

I need some help. im half way through wiring an m-unit blue into my 83 katana. the engine is an 88 1127 the ignitor is a 2005 gsxf750.

can anyone give me a wiring diagram of the ignitor to the m-unit? I have everything else talking to the m-unit just fine. its just the ignitor that's getting me all bollocked up.

thanks guys.

[Upshotknothole]

Search around, this has been brought up a lot of times. Usually you only want the M-Unit controlling power to the CDI.

[Upshotknothole]

Also, that 750 CDI has a rev limiter way higher than what that 1127 engine ever wants to see. Pay attention while riding, or swap it for an 1100 CDI or you're likely to blow the engine if you over rev it too many times.

[skunkworks]

9 hours ago, Upshotknothole said:

Search around, this has been brought up a lot of times. Usually you only want the M-Unit controlling power to the CDI.

I did search around and I can’t find a clear diagram that’s why I’m asking here.

[davecara]

Have a look at my 750M build thread, I put up some basic diagrams on there that may help you. Don't use the 750 CDI though, either buy an ignitech or find an 1100 one. 

[caferacerdan]

if you have a wiring diagram of the 750 i can tell you how to wire it to the M unit

[caferacerdan]

but i agree with @davecaraabout not using the 750 cdi as higher RPM limit wont do you any good

[skunkworks]

anyone have an 1100 ecm they don't need?

[caferacerdan]

think i might have one from a slabby 1100?

[Upshotknothole]

 

[caferacerdan]

infact the 1100 slabby CDI i had, i had running on an M unit! 4 wires in total...2 wires from signal. 1 to ground and 1 to 'ignition' on M unit

[skunkworks]

quick recap. 1988 1127. 2005 gsxf750 ECM. m-unit blue. all inputs work. ignition output provides 12 volts to coils.WTF?

ok so I've tried to wire it every way from Sunday and I have no spark.... I have 12 volts at the coils but no spark.

so when I ground the ECM  like it says in the revival cycles instructions it takes power away from the signal generator. (when I don't ground the black/white it has about 11 volts in the ground wire) and power returns to the signal generator.

I have tried the 100 omh resistor and it knocks it down to 8.5 volts (in the orange /yellow)when grounded(black/white) and still no spark. 

is it possible that both coils are bad?  its lucky it doesn't have a face because if it did it would of got punched by now.

please help 

 

 

[skunkworks]

a hi res wiring diagram for the ECM to the M-UNIT would be useful.

Edited October 21, 2023 by skunkworks

[Gixer1460]

There should never be voltage measured anywhere on the crank signal generator unless the engine is turning - it self generates millivolts level signal.

From memory and never used a M-Unit (but I assume it has a dedicated Ign output?) goes like this . . . . . 

M-Unit Ign output (12v) goes to 750 ICM / ECU / CDI (whatever you want to call it) orange/white wire AND the coil low tension terminals + side. (its a switched live)

M-Unit must have an earth to battery and chassis - Suzuki colour Black/white. The CDI also requires ground - Black/white.

From CDI there are two output wires - White and a Black/Yellow, each goes to a coil - (I think White is 1/4 and B/Y is 2/3? . . . . 50% chance of being right LOL)

From crank signal generator there are two wires - Blue and Yellow. These connect to CDI input side which should be Blue & Yellow!.

There is one last wire from CDI - Red/Black - this is the tacho signal and runs to the rev counter input.

Connected as above - you should have sparks and engine will run (with other variables supplied & coils - connected right way round LOL)

 

[davecara]

As said above, you shouldnt have any power down the VR sensor wiring.

I'll knock you a diagram up

[davecara]

Try that. GSXR and Bandit CDI's are wired slightly different but its not mega complex to decipher it. M-Unit powers the CDI and the Coils, the CDI earths the coil signal to fire them. VR sensor is straight forward, CDI earth is self explanitory and the black/red is RPM signal

credit to @Ben Slabbyfor the cdi pin outs 

Edited October 21, 2023 by davecara

[Gixer1460]

Apologies for getting some of the colours wrong - i'm used to 1100's LOL!

[skunkworks]

thanks very much  @Gixer1460 and  @davecara you guys are awesome. 

standby for results

[davecara]

2 hours ago, Gixer1460 said:

Apologies for getting some of the colours wrong - i'm used to 1100's LOL!

I think you’re right to be fair, Microsoft paint doesn’t let me do tracer colours without loads of faffing!