Greetings, all.

1985 K100RT renovation/salvation project.  This was a neglected bike needing more than just TLC. It's coming back together reasonably well after powder coat, some new parts, and many hours of cleaning.  As I've opted for a naked K, I've swapped out handlebar for clip-ons and I'm in the process of wiring the new speedo unit.  I went ahead and purchased an Acewell-6653, as I received no replies on my request for recommendations on aftermarket gauges that worked well out of the box (maybe those don't exist).  I've done some wiring to my house and it hasn't burned down, yet, but I'm a wiring novice.  So, here's were I'm at:

I've spliced the new harness onto the old one -- where they should work without modification.  Thus, left and right turn indicators, high beam, overheat warning light, neutral indicator, oil pressure, clock/power, and ignition/switch key are all connected (tentatively -- I haven't shrunk the shrink tube, yet).

A couple questions at this point.  I have many wires left over from the original harness.  My assumption is that I don't necessarily have to do anything with them and I could either wrap the pin connectors up pretty and tuck them in somewhere; or I could snip the old connectors off and preserve for somebody else.  I'd also have some OEM switches and sensors and their associated wires hanging out with no real purpose  Should I get rid of those and plug up holes as necessary and pull wires, or leave them be?  Is there anything that I would have to deal with so that necessary units function properly?

Examples:

Pins 2, 3, and 4 on the stock connector. The Acewell gets trained to recognize what gear the bike is in by calculating from speed and RPM and will not connect to the "switch gear indicator" wires  to the gear position sensor.  Thus, the gear position sensor is obviated.  Leave it alone?

Pins 12, 21, and 24:  Choke lamp, turn signal canceller, and "speedometer illumination", respectively.  These all go to the flasher unit.  Will the fact that these wires from the flasher unit go to dead ends cause any problem for the rest of the functions?  Pull the unused choke switch?

Pins 22 and 23: "tach pulse encoder".  The speedo impulse transmitter will be replaced by a reed switch, for which I've made a custom mount attached at the left fork tube pinch bolts.  I'm tempted to leave the old one in place (though I've seen a post where the author didn't like to leave that type of thing and inquired about how to plug the hole).  Incidentally, I have looked to see if there is an Acewell cable that will work with the K100.  It's not obvious that such a cable is manufactured.  Acewell makes cables for newer bikes and older Rs, but apparently not for me.

Pin 16:  "speed signal from ignition coil".  I've got two options here on the new unit: I can either wrap a few loops of wire around the plug wire or connect a different wire "to either the ECU rev counter output or to the primary side of the coil or to the pulse wire on an active spark plug cap."  Any preference?

I've got a temp sensor on the new unit, too, and will consider using it eventually, but for now it's going to wait.

Any advice will be greatly appreciated!

Cheers,

Frey

FreyZI wrote:A couple questions at this point.  I have many wires left over from the original harness.  My assumption is that I don't necessarily have to do anything with them and I could either wrap the pin connectors up pretty and tuck them in somewhere; or I could snip the old connectors off and preserve for somebody else.  I'd also have some OEM switches and sensors and their associated wires hanging out with no real purpose  Should I get rid of those and plug up holes as necessary and pull wires, or leave them be?  Is there anything that I would have to deal with so that necessary units function properly?

Examples:

Pins 2, 3, and 4 on the stock connector. The Acewell gets trained to recognize what gear the bike is in by calculating from speed and RPM and will not connect to the "switch gear indicator" wires  to the gear position sensor.  Thus, the gear position sensor is obviated.  Leave it alone?

Pins 12, 21, and 24:  Choke lamp, turn signal canceller, and "speedometer illumination", respectively.  These all go to the flasher unit.  Will the fact that these wires from the flasher unit go to dead ends cause any problem for the rest of the functions?  Pull the unused choke switch?

Pins 22 and 23: "tach pulse encoder".  The speedo impulse transmitter will be replaced by a reed switch, for which I've made a custom mount attached at the left fork tube pinch bolts.  I'm tempted to leave the old one in place (though I've seen a post where the author didn't like to leave that type of thing and inquired about how to plug the hole).  Incidentally, I have looked to see if there is an Acewell cable that will work with the K100.  It's not obvious that such a cable is manufactured.  Acewell makes cables for newer bikes and older Rs, but apparently not for me.

Pin 16:  "speed signal from ignition coil".  I've got two options here on the new unit: I can either wrap a few loops of wire around the plug wire or connect a different wire "to either the ECU rev counter output or to the primary side of the coil or to the pulse wire on an active spark plug cap."  Any preference?

Hi mate,

Last year I did a major overhaul of my electrics as I'm doing a cafe racer build, and in short, Ive got very few electrics left on the bike and it was running fine last time i tried (its off the road in bits at the moment).

This is all from memory, so please bear with my descriptions.

Anything relating to a gauge or display that you no longer use can be cut off (I've removed the original instrument panel completely and only have a an aftermarket speedo at the moment).

Getting the aftermarket speedo to work was a piece of cake once I accepted I had to use a new sensor, or at least it was the only answer at the time anyway. I just ran a reed sensor from the front wheel for the speed. For the rpm, I wrapped the sensor cable round one of the ignition leads and it works, although I can't verify its accuracy and would like a better solution if you have one!

Gear position sensor - theres a post on this forum from a while back detailing how to make an aftermarket one and it involved adding a switch to the sit under the gear pedal.. or something alone those lines. Theres a post somewhere on this forum detailing it all.

Choke and dash illumination - don't need - cut them. I've removed my ''choke'' cable as a whole because mine didn't stay on, and when you look at the throttle bodies, it only advances the throttle anyway, so I'm going to add a small lever down there instead to idy things up a little..

 Turn signal canceller? Do you mean the button itself? You need to keep that button if you're going to use the existing wiring for the indicators, but if not.. bin it!

Pulse sensor from the rear diff - I've left it in place as I haven't found (or bothered looking for) something to plug the hole with yet. I can't imagine it's any use as it feeds straight into the instrument cluster, which I haven't had for a while. So I'd suggest you can probably cut and remove that too.]

I'd be intrigued to know if you work out which wire is the RPM output from the ECU, as my reading seems a little inaccurate at the moment.

Hope thats all of some help. I've chopped a lot of electrics off my bike and it works for me, but please do think twice before you cut something, as once its gone.. 

If it helps, I multi-metered everything before I cut it, to see if it was active with anything I was doing. I've also removed a few of the relays and other gubbins out the fuse box.. theres a lot for accessory equipment I don't have - grips, hazards, ''special equipment'' etc..

Jase

Thanks for your thoughts, Jase.  I was beginning to think I'd been blacklisted from this forum due to my novice-ness.

The project has been moving a bit slow of late, on account of single dad-hood.  I have managed to get a few things done since my last post, not without the usual (for me) difficulties.  Here's a few pics:

Pic 1: LED signals.  Problem: I could have sworn I order one pair of resistors for 21W and two pairs for 10W bulb replacement, but my order came and I had three pairs of 9.8 Ohm resistors for 21W.  Hooked 'em up anyway, for kicks, and they work, just at about 200 blinks per minute.  Just received two pairs of 21.5 Ohm resistors, so I'm hopeful these bring the blink rate down to normal.  Aftermarket headlamp appears to work, but only when the switch is held down, so I guess I'll be pulling the switchgear apart to troubleshoot.  I was not surprised by this, as PO had shoved a piece of wood mulch in between the switch and the housing to shim it where it worked.

Pic 2: Hazard switch mounted in former handlebar mount hole.  My plan initially was to put the ignition switch in there, but I wasn't able to drill the triple tree out to 30mm on account of having sh!t tools for the job.  Someday, perhaps.  Meanwhile, I spent a bit of time trying to figure out where to mount the hazard switch and then how to fill a round hole with a square swtich.  Ultimately found a little aluminium colored but plastic cap and modified it to accept the switch.  Looks reasonably good, though probably not the elegant solution I was after.

Pic 3: Ignition switch mounted anteriorly to top triple tree.  I ordered a new boot for the rear master cylinder rebuild, and was able to pull the old one over the ignition switch in lieu of the "step plate".  It's attached via an inexpensive 30mm clamp via e-bay.

Pic 4: LED tail light.  Just took of the backing plate (which is designed to hold a license plate as well), turned it around, and screwed it on to the existing rear mudguard mounts at the end of the frame.  Looks pretty good, IMHO.  The indicator lights also utilize existing frame tabs.

T




Still yet to do (electrical-wise): I mounted a stainless bobber-style fender on the front and will have to route the wires for the new wheel speed sensor and RPM meter, train instrument unit accordingly, replace fuel pump and filter, cross fingers, hope it starts.

Questions: The turn signal canceler wire I was referring to is Pin 21 from the original harness.  Accoring to my instrument cluster plug pin arrangement diagram, it is called "tach sig. (cancel relay)" and is blue/green.  The wiring diagram shows it exiting from the speedometer and going directly to the flasher unit.  I suppose that the flasher unit then cancels the turn signal after sufficient acceleration out of a turn?  That's a function the aftermarket instruments don't appear to have.

Incidentally, I should say that (other than blink rate, as I have not yet put on the new resistors) indicators work, but the instruments show the right turn signal idiot light on constantly when key is on.

Oh, and the license plate holder that I have installed has an LED light, but my '85 RT doesn't appear to have had number plate illumination.  I suppose I'll run a wire from one of the accessory plugs for that light.  Any advice on this?

As always, thanks in advance for any insight.

Regards,

Frey

FreyZI wrote:Thanks for your thoughts, Jase.  I was beginning to think I'd been blacklisted from this forum due to my novice-ness.

The project has been moving a bit slow of late, on account of single dad-hood.  I have managed to get a few things done since my last post, not without the usual (for me) difficulties.  Here's a few pics:

Pic 1: LED signals.  Problem: I could have sworn I order one pair of resistors for 21W and two pairs for 10W bulb replacement, but my order came and I had three pairs of 9.8 Ohm resistors for 21W.  Hooked 'em up anyway, for kicks, and they work, just at about 200 blinks per minute.  Just received two pairs of 21.5 Ohm resistors, so I'm hopeful these bring the blink rate down to normal.  Aftermarket headlamp appears to work, but only when the switch is held down, so I guess I'll be pulling the switchgear apart to troubleshoot.  I was not surprised by this, as PO had shoved a piece of wood mulch in between the switch and the housing to shim it where it worked.

Pic 2: Hazard switch mounted in former handlebar mount hole.  My plan initially was to put the ignition switch in there, but I wasn't able to drill the triple tree out to 30mm on account of having sh!t tools for the job.  Someday, perhaps.  Meanwhile, I spent a bit of time trying to figure out where to mount the hazard switch and then how to fill a round hole with a square swtich.  Ultimately found a little aluminium colored but plastic cap and modified it to accept the switch.  Looks reasonably good, though probably not the elegant solution I was after.

Pic 3: Ignition switch mounted anteriorly to top triple tree.  I ordered a new boot for the rear master cylinder rebuild, and was able to pull the old one over the ignition switch in lieu of the "step plate".  It's attached via an inexpensive 30mm clamp via e-bay.

Pic 4: LED tail light.  Just took of the backing plate (which is designed to hold a license plate as well), turned it around, and screwed it on to the existing rear mudguard mounts at the end of the frame.  Looks pretty good, IMHO.  The indicator lights also utilize existing frame tabs.




Still yet to do (electrical-wise): I mounted a stainless bobber-style fender on the front and will have to route the wires for the new wheel speed sensor and RPM meter, train instrument unit accordingly, replace fuel pump and filter, cross fingers, hope it starts.

Questions: The turn signal canceler wire I was referring to is Pin 21 from the original harness.  Accoring to my instrument cluster plug pin arrangement diagram, it is called "tach sig. (cancel relay)" and is blue/green.  The wiring diagram shows it exiting from the speedometer and going directly to the flasher unit.  I suppose that the flasher unit then cancels the turn signal after sufficient acceleration out of a turn?  That's a function the aftermarket instruments don't appear to have.

Incidentally, I should say that (other than blink rate, as I have not yet put on the new resistors) indicators work, but the instruments show the right turn signal idiot light on constantly when key is on.

Oh, and the license plate holder that I have installed has an LED light, but my '85 RT doesn't appear to have had number plate illumination.  I suppose I'll run a wire from one of the accessory plugs for that light.  Any advice on this?

As always, thanks in advance for any insight.

Regards,

Frey

Looking and sounding good so far! love the seat/tail light! Looks really smart.

1. Turn signals - just cut the track on the relay instead of messing about with resistors. I've got LED indicators and thats all I did. The rapid flash is just a driver aid to let you know you've a bulb out. Its the same in cars too. Theres a full detailed guide on this forum on how and where to do it. it just takes a steady hand, stanley knife, and about 10 minutes of your time.

Headlamp - check you've got the high/low beam connected correctly. I made this mistake too as my new (old) Lucas headlamp needed rewiring and I connected it the wrong way round initially. Also confirm you've got a two element bulb in there, or a high and low bulb. Not just one single element bulb. Easy to check whats happening with multimeter - turn the lights on without the h/l connected and check for voltage on both wires, then again for high beam and connect accordingly.

2. Hazards - never felt the need for one if I'm honest. Its not a requirement by UK law/MOT standards, and a bike is only a foot wide, so indicators do just fine for me. Also my K100RS didn't have hazards fitted as standard anyway!

''Turn signal canceller wire''- I'm 99% sure that wire is redundant. The instrument cluster is like a computer screen. If you disconnect it, the remaining cables are void. It has no variable inputs to the ECU, only outputs FROM the ECU. Also worth noting, I've read somewhere that the ''ECU'' isn't actually one, its for Bosch's fuelling system and not much else IIRC. 

The indicators do not self cancel after a certain amount of steering/release. Again I'm sure theres talk of an optional extra to make them cancel after a certain duration, but its not a standard feature as far as I'm aware.

Number plate illumination - really easy one! Just tap into a wire coming from your tail light and earth it to the chassis. When the lights are on, the number plates on too! Wire in parallel, not series, or you'll dim one or both.

Jase

Have you considered junking the OEM flasher relay and fitting a three-pin one instead? It'll remove a lot more wiring and also give you free run of ebay for Japanese switches, throttles and clutch levers. See here:

https://www.k100-forum.com/t10150-wiring-in-non-bmw-handlebar-switches

Dai wrote:Have you considered junking the OEM flasher relay and fitting a three-pin one instead? It'll remove a lot more wiring and also give you free run of ebay for Japanese switches, throttles and clutch levers. See here:

https://www.k100-forum.com/t10150-wiring-in-non-bmw-handlebar-switches

Never saw this post, but wish I had! Thats another job to do now!

JaseYPK wrote:

Dai wrote:Have you considered junking the OEM flasher relay and fitting a three-pin one instead? It'll remove a lot more wiring and also give you free run of ebay for Japanese switches, throttles and clutch levers. See here:

https://www.k100-forum.com/t10150-wiring-in-non-bmw-handlebar-switches

Never saw this post, but wish I had! Thats another job to do now!

Ditto.  To be honest, at this point, I'll be happy to get the thing running and inspected.  Maybe in a second round of modifications...

FreyZI wrote:

JaseYPK wrote:

Dai wrote:Have you considered junking the OEM flasher relay and fitting a three-pin one instead? It'll remove a lot more wiring and also give you free run of ebay for Japanese switches, throttles and clutch levers. See here:

https://www.k100-forum.com/t10150-wiring-in-non-bmw-handlebar-switches

Ok, Dai.  I'm willing to try a three-pin LED relay.  I've reviewed -- but not educated myself about -- your post on the subject.  I don't care to change any of the handlebar controls, electrical or mechanical, at this point.  Any reason this plan won't work with stock?

Yes i.e. it won't work with stock. The BMW wiring loom effectively has two separate indicator circuits; you tell it what you want it to do on one circuit and the indicator relay then decides if it's going to flash the bulbs on the other circuit. If you check the (say, left side) indicators, the bulbs are on a blue/red wire but the indicator switch is on a blue/brown wire. On a Japanese switch the incoming power from the relay is directed on to the required bulbs by the operation of the indicator switch i.e. both switch and bulbs are on the same wire.