of what exactly ? building a trike or trying to get engine to run without wiring loom
ST 1100 Electrics
- Thread starter merv shepherd
- Start date
I'm just scratching my head and wondering - why? I'm not seeing the purpose/reasoning?
I'm obviously missing the whole point.
Hi
The reason i want to do this is because i'm turning the ST 1100 into a trike and i'm going to run it naked. So i want to thin down the electrics to make it easier to hide all the wires.
Merv
Yep that's it, got one waiting to be fitted. Very expensive but a nice little unit, as this is a one off i thought why not
Merv
If you would, that also would be a big help, i am keeping the original tank and pump
Merv
For the fuel system, as far as electrics go you have several choices:
1) Hook up a direct 12v feed to the fuel pump with a switch and switch it on manually
2) Use the original ST1100 circuitry
3) Hook it into your m-unit
4) fit an external fuel pump and suck it out of the tank (this is a variation of 2))
Option 1) is simplest, just run a wire from 12v fuse box to a switch and from switch to +ve terminal on top of fuel tank and a wire from the -ve terminal on tank to gnd. Turn it on for a couple of seconds before you start to prime the carbs then start engine. just remember to switch pump off when engine not running !!! The downside to this is that the pump is pushing against the float valve needles continuously and although there is a mechanical pressure regulator on the end of the pump its not good for it.
Option 2) will require the Fuel Cut Off Relay (FCOR) and Fuel pump and fuel tank wiring to be left intact or reproduced. On your bike this is easier because the FCOR and pump takes the 12v from the Ignition Control Module (ICM) (as well as the 'engine running' sense) , so having already got the ICM working earlier; this builds on that. This of course depends on the FCOR being serviceable, its a custom Honda part.
Option 3) would need some thought. This provides better 'automation' than option 1) but not as good as option 2) (The automation is this: Prime fuel line for 3 secs then stop and wait until engine running before pumping fuel again, when engine stops running, stop pumping fuel). It would reduce the wiring though.
Option 4) you will see this has been convered fairly extensively on the forum, an aircraft style fuel pump is usually recommended, it sucks through the existing fuel pickup. You mentioned that you got the engine to run okay so that infers the fuel pump is working okay for the moment. If it packs up then consider this option and hook it into the m-unit
I will do a bit of research into the m-unit https://motogadget.com/shop/en/m-unit-basic.html , I see it has a timer capability for turn, maybe that can be adapted to work for the fuel pump prime
EDIT: I had a look at the m-unit manual, you could wire the fuel pump into Aux1 and configure it to be active when ignition on, this would work for option 4) especially well
also, I suggest connecting the Black/White wire at the ICM to the "Ignition" terminal on the m-unit
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Do you plan on using the bluetooth and the motogadget app ?
Option 2 sounds good, if you could show me the coloured wires and where they go would be a big help, have you got any ideal how you would connect the fuel system into the m-unit and would it be easier than option 2.
Understood, i will have a look at the manual for that version and see if there are any major differences
m-unit : This uses a switched Ground for inputs rather than a switched 12v.
The stock system is mostly switched 12v with some switched earth for protection circuits.
This will make it challenging to use any existing wiring so for the fuel pump I now see the easiest is to buy an external suction pump and wire it into the Aux terminal of the m-unit, in which case you can lift out the existing pump from the tank and simply have a pipe with a strainer connected.
The pump make that is mentioned often is Facet https://www.facet-purolator.com/
There is a good thread here that talks about the different types of pump : https://www.st-owners.com/forums/threads/facet-fuel-pump-questions.133234/post-1689416
The stock system is mostly switched 12v with some switched earth for protection circuits.
This will make it challenging to use any existing wiring so for the fuel pump I now see the easiest is to buy an external suction pump and wire it into the Aux terminal of the m-unit, in which case you can lift out the existing pump from the tank and simply have a pipe with a strainer connected.
The pump make that is mentioned often is Facet https://www.facet-purolator.com/
There is a good thread here that talks about the different types of pump : https://www.st-owners.com/forums/threads/facet-fuel-pump-questions.133234/post-1689416
if you need any replacement or different connectors, this online shop is a good starting place, even if just to find out the name of a certain plug you are looking at http://www.cycleterminal.com/motorcycle-connectors.html
I built a wiring harness from scratch for a friend's older HD. I started by finding a wiring diagram on-line, and altered it by removing everything we were eliminating from the drawing, and colored the remaining lines to match the factory wire colors.
I suggest doing something similar, working with a good wiring diagram, and determining what you want to omit. It's better to work from a plan, and you're less likely to forget something and have to add it later, ruining your custom look and function.
I also think the best approach, since you have an existing harness, is to strip it and remove whichever wires you won't need. I suggest leaving one or two wires in strategic locations as spares. Then re-wrap it carefully and snugly with good quality tape.
I suggest doing something similar, working with a good wiring diagram, and determining what you want to omit. It's better to work from a plan, and you're less likely to forget something and have to add it later, ruining your custom look and function.
I also think the best approach, since you have an existing harness, is to strip it and remove whichever wires you won't need. I suggest leaving one or two wires in strategic locations as spares. Then re-wrap it carefully and snugly with good quality tape.
Thanks Steve for being so helpful, did you double check the wires coming of the Ignition Control Module that you got them right. you did say it was early morning when you did it 
Merv
Merv
Hi Larry
That's what i'm trying to do. I didn't want to just bypass the clutch safety switch, the bank angle sensor, and the side stand safety switch. I want to completely eliminate them from the loom, but those circuits are tired into the Ignition Control Module. I need to know how to rewire the Ignition Control Module so the bike will function how it should without those circuits attached.
This is where Steve has been most helpful, i have been trying to find this information for the last eight months or more and hes the only one who has come up with anything.
Merv
Oh,that's easy with my wiring diagram. I could tell you what needs to connect directly to what.
Added: I have been studying my Clymer and Honda diagrams since I bought the bike over 2.5 years ago.
If you have a wiring diagram to look at at the same time, I can help you do exactly what you want, wire by wire.
I can tell you what you must keep, what you can eliminate and how to, and how to connect what remains.
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Hi Merv, yes double checked and no changes. Will be a fun projectThanks Steve for being so helpful, did you double check the wires coming of the Ignition Control Module that you got them right. you did say it was early morning when you did it
Merv
Hi Merv
Working from your photo, top down (I just did this quickly in the morning, will double check later and update if necessary, the yellow/blue proved interesting !)
Wire Colour Purpose Action Note Pulse Generator leave connected ensure same colour wires connected at engine (pulse generator) Ground leave connected (or run wire to negative, see note) ensure you have a green wire connected to frame at some point or run a green wire from here to -ve Pulse Generator leave connected Switched +ve supply leave connected (see note) This is supplied through RUN switch, if you don't use RUN switch then run 12v positive here. This also supplies 12v rail on Fuel Cut Off Relay. when initially supplied with 12v this triggers Fuel Cut Off relay to power fuel pump for 2-3 secs then turn off until yellow/blue active Tachometer optional this feeds the tacho, leave connected if you want the tacho to function Sidestand
(up = grounded)cut and wire to Ground Neutral
(in neutral = grounded)cut and wire to Ground (or you can simply connect to the Green/white if you have just grounded it) to Gnd via transistor : coil 1,3 leave connected This also supplies 'engine running' sense on the Fuel Cut Off Relay (FCOR). to Gnd via transistor : coil 2,4 leave connected
Not sure if you would like the theory behind it or not, either way is good for me. I'll include some basic theory as we go but I can dispense with it if you would just prefer the 'actions'
Here is a schematic showing how the ECM works:
When I refer to the 'transistor' its hidden inside the ECM box. The transistor opens and allows current to flow through the primary and 'charge' the coil, then the transistor is closed and the secondary coil discharges through the spark plug. The coil ignites two spark plugs at the same time (1&3) or (2&4) , only one spark is used the other is wasted
You can see on the diagram the pulse generator and the switched 12v supply
Hi Steve
Sorry to be a pain, can i now cut the plug of now leaving tails to connect to there circuits. Just a couple of questions
no 1, the light green wire for the neutral light, you said wire to ground will this still keep my neutral light if not how can i keep it.
no 2, the yellow/blue wire what do i keep it connected to
no 3, blue/yellow wire also what do i keep it connected to
Also will wiring it this way get rid of the bank angle sensor .
Merv
[ICM - Ignition Control Module ]
No1: Cutting the light green means the ICM doesn't consider the neutral protection logic, you can just cut and connect to Ground (i.e. battery -ve) . We can separately look at how to hook up the neutral light separately purely for indication purposes
No2/3 These MUST stay connected to the primary of the coils, the ICM controls the spark by pulsing these two wires , so if you have a look at the coils as installed you will see the same colour wires and this shows you where to connect them from ICM. If the wires are already disconnected to the coils then let me know and I'll go digging to find the appropriate pins on the coils
Bank angle sensor will no longer be looked at so can be removed.
Just want to put in a caveat, removing all the protection circuitry does push the reponsibility back onto the rider to not try and start in gear and the engine will continue to run if the trike tips over ! Using the m-unit it will be possible to gradually bring most of these protections back at a later stage if you so wish
Hi Steve
Thanks for clearing that up, I would like to keep the neutral light as that is the only indication of the gears and I believe part of the MOT.
If you could show me how to connect up a neutral light I would be grateful.
Merv
If you look on the engine you will find a 4pole socket and plug, the wires from the plug will be coloured :
Light Green
White/Yellow
Yellow
Blue/red
Assuming you are not using any of the existing harness then cut the wires on the plug side (i.e the side going into the harness and away from the engine) and splice into the tails on the plug as follows:
The White/Yellow & Yellow are connected to the ICM as shown in the table (they are from the Pulse Generator).
The Light Green wire, should be cut and then run a cable from there to the Neutral bulb (look for Lightgreen/Red wire at neutral bulb and cut that and connect there)
The Blue/red wire should be cut and then a cable run from there to the Oil Pressure bulb (look for the Blue/red wire at oil pressure bulb and cut that and connect there)
You will need to run a 12 ignition switched supply to the Neutral and Oil P bulbs (look for Black/brown wires, cut them and connect 12v there)
Note: The neutral and oil pressure bulbs are currently ground switched i.e. they have permanent 12v supply rail (when ignition is on) and the other side of the bulb is connected to the respective switches , the switches (oil & neutral) are closed when it is low oil pressure and gearbox is in neutral
EDIT: corrected mistake in colour mentioned for oil pressure bulb, corrected to Blue/red
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