Retrofitting a Koso Speedo - technical help please

RazMan

Rocket Addict
Joined
Mar 31, 2022
Messages
264
Location
Christchurch, UK
Ride
2022 R3 GT, 2011 America
As my odometer stopped working some time ago I decided that the cost of a genuine replacement was not worth it and went for a Koso RXF unit.

It looks a little bit like the later Rocket's unit and modernises the 2300 nicely. The only issue is getting it to play nicely with the on-board electrickery . Luckily my Classic doesn't have the new fangled CANBUS to complicate things even more but I have still got a few 'challenges' to deal with before my install is complete.
I have gleaned some very good info from our resident gurus (@DEcosse in particular) and made up a connector to replace the 20 pin loom that hooks up the existing clocks - here is my Pin-out list....


I have succeeded with most of the connections but have a couple of issues....

  1. Pin 9 (high beam) lights up the correct light but stays on for low beam too! Measuring the voltage at the pin I get a good 12V on main beam but still get 8V on low beam which keeps the LED 'on'. Is there any solution to this? I don't really want to run a fresh connection direct to the main beam in the headlight but I will as a last resort.
  2. Pin 1 (Tacho) does not appear to work. Again, I could run a fresh connection to one of the coils but would rather do it the 'proper' way if possible.
  3. Pin 18 (speedo power) - am I right in thinking that it needs to be linked to Pin 2 (ignition power) to energise the speedo ?
If I can get these problems solved, I can then start on the temperature sensors and the fuel gauge which is another can of worms.
Any help would be appreciated
 
Last edited:
Well I tried all kinds of settings, connections, swear words etc but couldn't get the tacho to wake up using Pin 1 on the loom. I have now connected it to the +ve terminal of the front coil so hopefully that little challenge has passed and I can finally get that needle bouncing.

Now onto the fuel gauge, and I am not quite how to hook it up. Pin 4 is a 'low fuel' light so I am guessing that it will not be the right point for a gauge which requires a set range of resistance to work properly. So it must go to the socket which the old fuel gauge plugged into (duh) 4 pins on this one - is it the Green/red? Also, any ideas on which resistance values to put into the Koso to get a realistic gauge?
 
I think
Very often the fuel level is really high.
Should b able to tap into the voltaage going back to ecu. 5 volts going into the the sensor and (in theory 1/2 tank) would be 2.5 volts going into ecu. Should b able to tap this voltage and set to the dash.
Temp sensor same thing
I am assuming that your system will work with the 5 volts
 
The main issue for me is that the Koso setup only gives resistance values so voltages from the ECU would just complicate things. There was originally a fuel gauge connected (which didn't work) so I am guessing that hooking up another gauge shouldn't be too much of a challenge, making cutting into the ECU's loom unnecessary. I got the speedo working now (hooray!) and all of the idiot lights so the fuel gauge is the last thing to figure out (apart from some temperature sensors which are just a bonus)
 
Just in case anyone is thinking of doing this retrofit, I can definitely recommend this Koso RXF. It has more functions than you will ever need but you can pick and choose which ones you want.
For reference, the speedo settings ended up to be 4 pulses per revolution using the bike's sensor. The tacho refused to work that way so I ended up connecting to the front coil (which I could access without lifting the tank) The fuel gauge is set to 'SW' and the display starting flashing at me today (not sure it was accurate) to tell me I am low on fuel.
I have yet to do anything with the two external temp sensors but the ambient sensor works well.
 
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