SIP Lambretta Digital Speedo
Posted: Sat Apr 07, 2012 5:05 pm
Finally got around to fitting my SIP Lambretta speedo today.
I'm running a Wassell full DC system on the bike in question, a SIL GP.
Connections
I followed the instructions (maybe
) but essentially there is a "powerbox" which connects between the device and the power supply. 3 wires need to be joined into the headset: Red = Battery +12V; Brown = +12V supply to the lights; Black = Earth. (There is an AC option too 
)
The speedo cable connection is the Italian fitting, NOT Indian, so I had to change the cable.
The next connection I made was the external button. This is a small button, about 10mm diameter, which is attached to a convenient position with a self-adhesive pad. I stuck mine inboard of the dip switch on the throttle casting. (They supply an alcohol swab to ensure a clean surface.) This button is used to both change modes and to enter the settings.
The other thing to connect is the Cylinder Head Temperature sensor. This is an aluminium ring which fits under the spark plug. (I didn't fit this, as yet anyway, because I already have an EGT fitted and mainly I couldn't get the bugger under the plug because it fouled on the head cowl.)
Settings
Measuring units: The choice is between Degrees F and Miles, or Degrees C and Kilometers. So if you're like me and prefer Degrees C and Miles, you're unlucky!
Speed signal setting: Now because a) I'm a bit thick, and b) the English translation of the document leaves a bit to be desired, I initially set this to "Ext" and found later (when it didn't work) it needed to be set to "Int".
Circumference setting: This is the distance travelled for one revolution of the wheel. To do this as accurately as I could be bothered I marked the wheel with masking tape, sat on the bike and walked it 10 revolutions, marking the road at the start and finish (this is where an attractive assistant comes into play)
Divide the length of the 10 revolutions by... you can guess the rest! Mine came out at 1287mm.
There's also a "Gear Ratio" setting which I reckon must be a hang over from the preceding Vespa speedo design. I set this to 1.
RPM pulse setting: There's a table in the booklet which give loads of alternatives for 2-stroke; 4-stroke; number of pistons. I chose "1" which corresponds to 1 piston and 2 stroke (I don't have a fancy Variotronic thingy which sparks twice every rotation).
Testing:
Initial tests show the digital speed works (once I set the input correctly) but I plan to stick the TomTom on it over the next few days to calibrate it. It should be simple enough to tweak the wheel circumference entry until it's right. 
Now, the problem. I can't get any reading from the tacho. I've seen this before with tachos when you try and pick the pulses up from the wiring loom. Having a Wassell system with a battery I reckon all the ignition noise is smoothed out. I'd appreciate an electrical perspective on this from the experts out there (come on, you know who you are!! )
I'm running a Wassell full DC system on the bike in question, a SIL GP.
Connections
I followed the instructions (maybe
) but essentially there is a "powerbox" which connects between the device and the power supply. 3 wires need to be joined into the headset: Red = Battery +12V; Brown = +12V supply to the lights; Black = Earth. (There is an AC option too )The speedo cable connection is the Italian fitting, NOT Indian, so I had to change the cable.
The next connection I made was the external button. This is a small button, about 10mm diameter, which is attached to a convenient position with a self-adhesive pad. I stuck mine inboard of the dip switch on the throttle casting. (They supply an alcohol swab to ensure a clean surface.) This button is used to both change modes and to enter the settings.
The other thing to connect is the Cylinder Head Temperature sensor. This is an aluminium ring which fits under the spark plug. (I didn't fit this, as yet anyway, because I already have an EGT fitted and mainly I couldn't get the bugger under the plug because it fouled on the head cowl.)
Settings
Measuring units: The choice is between Degrees F and Miles, or Degrees C and Kilometers. So if you're like me and prefer Degrees C and Miles, you're unlucky!
Speed signal setting: Now because a) I'm a bit thick, and b) the English translation of the document leaves a bit to be desired, I initially set this to "Ext" and found later (when it didn't work) it needed to be set to "Int".
Circumference setting: This is the distance travelled for one revolution of the wheel. To do this as accurately as I could be bothered I marked the wheel with masking tape, sat on the bike and walked it 10 revolutions, marking the road at the start and finish (this is where an attractive assistant comes into play)
Divide the length of the 10 revolutions by... you can guess the rest! Mine came out at 1287mm.There's also a "Gear Ratio" setting which I reckon must be a hang over from the preceding Vespa speedo design. I set this to 1.
RPM pulse setting: There's a table in the booklet which give loads of alternatives for 2-stroke; 4-stroke; number of pistons. I chose "1" which corresponds to 1 piston and 2 stroke (I don't have a fancy Variotronic thingy which sparks twice every rotation).
Testing:
Initial tests show the digital speed works (once I set the input correctly)
but I plan to stick the TomTom on it over the next few days to calibrate it. It should be simple enough to tweak the wheel circumference entry until it's right. Now, the problem. I can't get any reading from the tacho. I've seen this before with tachos when you try and pick the pulses up from the wiring loom. Having a Wassell system with a battery I reckon all the ignition noise is smoothed out. I'd appreciate an electrical perspective on this from the experts out there (come on, you know who you are!!
)
the clock is hard to read when riding. Not yet set everything up. My conclusion and this is a pretty obvious thing to say but you need to really want and appreciate the rev counter as it dominates the speedo but is in virtually the same position as an original speedo. Nice bit of kit and well made. Oh and my LED festoon bulb doesn't work, something about the speedo taking too much of the power..... 
