LCGB Forums

Just putting a SIP speedo in my GP.
I'm sure this has been asked so many times before but.
Can someone point me to the link on the set up please?
SIL GP150 box. What's my gear ratio?
What's the length of 1 revolution on a standard 350x10 wheel?
175 stage 4, 28mm Delorto PHBH, Sterling expanshion
How the hell do you fit the temperature sensors via the spark plug sensor? Gone through 2 already. Gets caught between the plug spanner and the cowl. Does the head cowl need to be trimmed to suit? Am I better bolting this through a head fin?

How do you fit the digital speedo cable? I have the cable and the magnets and bracket. Any advise welcome?
Any other useful pointers welcome.

I haven't got a DIP speedo, but if you need to know your wheel diameter, you do not need know your gear ratio. Put a chalk mark on the bottom (6 o'clock) of the front tyre and a corresponding mark on the road. Wheel the scooter forward until the mark on the tyre is at 6 o'clock again and put a mark on the road. Now measure between the two marks on the road. This is the diameter of the wheel/tyre.

You will get a better result if the tyre is at correct pressure, you have your weight on the scooter and you do 3 or 5 rotations of the wheel (and divide by 3 or 5.

My mate has his temp sensor outside the cowling, on the long nut. 60degrees is a very comfortable figure.

[quote="Knowledge"]I haven't got a DIP speedo, but if you need to know your wheel diameter, you do not need know your gear ratio. Put a chalk mark on the bottom (6 o'clock) of the front tyre and a corresponding mark on the road. Wheel the scooter forward until the mark on the tyre is at 6 o'clock again and put a mark on the road. Now measure between the two marks on the road. This is the diameter of the wheel/tyre.

That will give you the circumference of the wheel.........................personally i blame the government cuts in education

Watfordwhite wrote:Just putting a SIP speedo in my GP.
I'm sure this has been asked so many times before but.
Can someone point me to the link on the set up please?
SIL GP150 box. What's my gear ratio?
What's the length of 1 revolution on a standard 350x10 wheel?
175 stage 4, 28mm Delorto PHBH, Sterling expanshion
How the hell do you fit the temperature sensors via the spark plug sensor? Gone through 2 already. Gets caught between the plug spanner and the cowl. Does the head cowl need to be trimmed to suit? Am I better bolting this through a head fin?

How do you fit the digital speedo cable? I have the cable and the magnets and bracket. Any advise welcome?
Any other useful pointers welcome.

Thanks to Sir Sticky (surely a knighthood is imminent?) page 33 of his manual shows circumferences for all the tyres that will fit 'our' rims. The 3.5 x 10 tyre states a circumference of 1357 mm.

As for fitting, can a magnet be fitted via the LH side on one of the SIP long nuts you have/had then a bracket be concocted to fit from the underside of the link pivot nut?

It ought to be do-able as the longer tube valves would catch the pivot bolt so I must be in the right area......Gulp!

The under spark plug sensor fitting is really tosh.
I drilled my head so the sensor tip is 3mm directly over the centre of the combustion chamber.
You will need an M4.5mm tap if you decide to go this route.
These RTD type sensors do suffer from drift after while. When they are new they will display the correct ambient temp of a cold engine which is going to be the same as the surrounding air.
Mine has been in service for about 16 months / 3500 miles and now displays about 30F less than it should.
A calibration function would have been nice.

That's a cracking idea Mark. Will try it this afternoon. I should of known to see Sticky's advice first ...

Thanks for the info Fast. I may not bother with the temp sender then. TBH I wouldn't know what the max safe temperature is anyway. The digital speedo was always the most important thing, followed by the Rev counter and the low fuel light.

If using the wheel mounted sensor, you don't need a magnet, the sensor picks up just fine aiming the sensor at the heads of the wheel studs. I managed to get my sensor to fit inder the plug but it needed a fair bit of dremelling to the fins and cowling to allow the ring to fit flat enough to allow a plug socked to be used. The only problem really is my plug kept coming loose and actually came right out on the way back from Adria

Watfordwhite wrote:That's a cracking idea Mark. Will try it this afternoon. I should of known to see Sticky's advice first ...

Thanks for the info Fast. I may not bother with the temp sender then. TBH I wouldn't know what the max safe temperature is anyway. The digital speedo was always the most important thing, followed by the Rev counter and the low fuel light.

I would guess the max safe temperature to be just a few degrees less than a holed piston You will of course need superman's eyesight to see the display reading whilst traveling at pace. It's probably the most useless piece of crap to get fitted to a lammy these days. At full chat on a summers day mine has seen 305 Farenhiet. Is that good??????? Oh... and you can only have centigrade if you choose KPH for the speedo. Such a well thought out product for the UK market. The largest market in the world for Lammy parts. Don't give up your day jobs boys.(unless it's in design or marketing)

Mine shows MPH and centigrade at the same time.
Think it's a version 2 for series 1&2.
The reading doesn't jump out at you but I find it easy enough to read. Mounting the sensor is proving my biggest headache.

Marty ULC wrote:Mine shows MPH and centigrade at the same time.
Think it's a version 2 for series 1&2.
The reading doesn't jump out at you but I find it easy enough to read. Mounting the sensor is proving my biggest headache.

Yes, pretty sure mine does too but agree with FnF, the display for anything other than the speed is near useless.

Regarding the R&D, it was originally designed for the PX range but then got re-packaged for Lambretta usage...doubt if the screen is any more readable on a Vespa either though.

Hmmmmm. A MK3 would need to have a more readable display. Can't see that happening.
Anyway.... Due to the angle, it is also hard to read on a bright day. I still say that a redesigned headset top ready to take a better made clock set is the answer. I might have a go at this when I get around to doing my GP.
But then again ...... Pigs might fly first.

Morning all. I put my temp sensor on top of the plug; as everyone says between the plug and cylinder head required too much messing about for my liking. Also it can cause air leaks as metal breaks when tightening the plug in.
I hold the sensor on the plug with a spare spark plug rubber cap that I cut slightly and then the plug cap holds the sensor onto the plug.
This will I guess give a lower temp reading but having killed / blown up too many engines I find this guide helpful so far (touch wood!).
Obviously each engine is different but those who know more than I suggest 200 degrees C is red zone hot! Because my sensor is on top of the plug (and i’m Old & more cautious) I’m looking for somewhere for a cup of tea around 170 degrees. The sensor should also show quick changes in temp which would worry me.

I'm sure it wouldn't be beyond them to add a flashing overheat function.