Cockpit wiring

[Samppa2]

Hi

I'm about to take off original "instrument panel" and replace it with aftermarket speedo.

I would still like to have warning lights and I'm planning to get small led lights to do the job.

There is a socket with many wires going inside the original instrument panel. How do I know, which wire is for which warning light in the original panel..?  

[Bob_Roller]

You need a wiring diagram to determine what wire illuminates what light .

One warning right now, the GEN light needs a resistor installed if you use an LED, or your charging system will not work .

Also, you need to proper wiring diagram for the year bike you have,  the '79-80 bikes commonly referred to as the first generation R65, have wiring differences from the '81-85 twin shock R65's also called the second generation R65 .

[georgesgiralt]

Try to keep the round plug unmolested. The only way to get a new one is to buy a complete wiring harness .... Just in case you want to sell the bike to a guy wanting the original look.

[montmil]

I'm about to take off original "instrument panel" and replace it with aftermarket speedo.

What aftermarket instrument are you considering?

[Barry]

a      High Beam
b      Illumination
c      Charge lamp
d      Neutral Lamp
e      Oil Pressure


To complete the picture for those pins that are not obvious from which lamp they connect to :

Pin 5 is the Tacho impulse
Pin 6 is the live feed
Pin 8 is earth

[Samppa2]

Thanks a lot for you all!

I forgot to mention, my bike is R45, 1981. Will the picture Barry sent cover my bike as well?

The speedo I'm looking for is T&T Electtroncs' device, sold by Louis. For some reason I couldn't copy the address field... But the item number at Louis is 10034532.

[Barry]

I forgot to mention, my bike is R45, 1981. Will the picture Barry sent cover my bike as well?

While there are some differences in the wiring diagrams that connector and it's numbering is the same.

[Einar]

One warning right now, the GEN light needs a resistor installed if you use an LED, or your charging system will not work .

Could you elaborate a bit on this? Does it mean that the battery wont charge without the resistor?


Also, in order to remove the cockpit, do I need to unscrew the ignition?
In fact, I'm looking for an "install universal speedo for Dummies"-guide.

Lots of useful info here.
Thank you.

[montmil]

One warning right now, the GEN light needs a resistor installed if you use an LED, or your charging system will not work.

Could you elaborate a bit on this? Does it mean that the battery wont charge without the resistor?

Also, in order to remove the cockpit, do I need to unscrew the ignition?
In fact, I'm looking for an "install universal speedo for Dummies"-guide.

Lots of useful info here.
Thank you.

The GEN lamp is a 12v-3w filament-style bulb. The resistance created by the bulb's filament is used as an exciter to wake up the alternator and have it begin charging. Should the bulb burn out, there will be no charging at all. The back-up circuit is nothing more than a 330-ohm resistor wired parallel to the GEN lamp, providing the same resistance as the bulb. LED bulbs will not work as a primary GEN lamp.

Here is what I used to build the resistor circuit. Note the blue and green wires are the same color as utilized by the GEN lamp circuit.



Solder the resistor to the wire leads. Add short pieces of shrink tubing over the soldered joints. Finally, cut a section of zip tie and use it as a stiffener to protect the resistor. Another bit of shrink tubing covers all.



The front end of my 1981 R65 is altered. No more instrument nacelle or headlamp bracketry. Small cafe-ish faring. I use TrailTech Vapor digital instrumentation on the '81 R65 and my 1978 R100S. I also have no GEN lamp on the bikes, relying solely on the 220-ohm resistor to keep the alternator busy.

The R65's steering stem hex head opening has a removable LED oil pressure lamp.

[Einar]

Thank you for enlightening me, Monte!
That is very clear!

I assume I am not guaranteed the same resistance with a 3rd party bulb, even if is a non-LED display, so I should probably prepare to install a 330ohm resistor?

[montmil]

Thank you for enlightening me, Monte!
That is very clear!

I assume I am not guaranteed the same resistance with a 3rd party bulb, even if is a non-LED display, so I should probably prepare to install a 330ohm resistor?

Stock bulb is a small 12v-3w. If your new instrumentation meets these specs, you're golden. If the new instrument has LED lamps, you should still be OK -as far as the dash lamp goes- as the resistor circuit will handle the alternators 'excitement'. You just may not have the same charging circuit trouble shooting guidance as the stock GEN lamp provides.

[Barry]

It's not that critical that the bulb has a rating of exactly 3w. If you study  the original riders handbooks (and believe what they say) the early models have a 1.2w bulb and the post 81 models a 3W bulb.  As long as there is sufficient current passing through the bulb the alternator rotor will be excited to produce a magnetic field and kick start the alternator into producing output.

That a smaller bulb is sufficient to do that job is evident from the fact that a 330ohm resistor works and that's only equivalent to a 0.5 W bulb.  An LED might draw even less power and that would explain why they don't do the job without an additional resistor in parallel.

Besides the fact it's not really needed, the reason a bypass resistor exactly equivalent to a 3 W bulb is not recommended is that it would obviously dissipate 3 w of heat and therefore have to be physically a large resistor rated at a minimum of 3 W which is not convenient.

In choosing the value of the resistor or bulb there will be some difference in how they work. Lower value of resistance will kick start the alternator in to producing output at lower revs. Someone, presumably Snowbum has done the tests and concluded that 330 Ohms or 0.5 watts is a reasonable compromise and does the job.

[Einar]

Thanks Monte and Barry. I haven't yet found a speedo but I will probably end up buying some universal model off eBay so I will check what comes with.