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Speedo Reading

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

Speedo Reading

Postby burnside » Sun Oct 14, 2018 2:58 pm

I’ve just replaced a broken speedo cable, ensured it was the same thicker Indian cable, but now the speedo is reading over double the actual speed. Any ideas on what could have caused this and how to resolve?
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Re: Speedo Reading

Postby Knowledge » Mon Oct 15, 2018 9:00 pm

That is one hell of a good tuning part you purchased there matey.

People pay far more than that to buy go-faster parts for their scooters and never get double the speed out of their engines. Well done.
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Re: Speedo Reading

Postby Warkton Tornado No.1 » Mon Oct 15, 2018 9:54 pm

My initial thoughts are for that to occur, there can only be a couple of events that have changed.

The RPM of the speedo drive. However, that cannot have happened with just an inner cable change, so you can discount that possibility!

More likely is the proximity of the rotating magnet within the speedo itself. If that has been pushed closer to the needle centre (the part that receives the magnetic 'signal' from the rotating magnet) that will increase the amount of 'drag' & the consequence will be higher, faster readings.

I hope that helps as from memory, when I used to bother to try & 'calibrate' speedos, it was a tweak that would work, to an extent :)
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Re: Speedo Reading

Postby burnside » Tue Oct 16, 2018 5:29 pm

It is a weird one, the odometer reading is fine just the speed and it is exactly double the speed my GPS is showing...it was a good few weeks before I got round to replacing the cable but not sure what could have caused the magnet to move, if that is what has happened. I've ordered a new complete cable so will try that to see if it makes any difference, but I always use my Garmin Forerunner anyway for accurate speed and the odometer is working so might just leave it as is....not as if Lambretta speedos are particularly accurate anyway

Knowledge wrote:That is one hell of a good tuning part you purchased there matey.

People pay far more than that to buy go-faster parts for their scooters and never get double the speed out of their engines. Well done.


The GT186 kits are good but going off the clock in 3rd is really impressive :lol:
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Re: Speedo Reading

Postby shane BBoys » Wed Oct 17, 2018 12:14 am

Mine does something V similar I always use my phone speedo app, then at least i get a true reading, always have a battery pack pack up on trip over 2 hours though.

Shane.
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Re: Speedo Reading

Postby burnside » Wed Oct 17, 2018 9:22 am

shane BBoys wrote:Mine does something V similar I always use my phone speedo app, then at least i get a true reading, always have a battery pack pack up on trip over 2 hours though.

Shane.


That's where my Garmin Forerunner 201 comes in handy, GPS speed with distance, time, max speed, etc. and a 14 hour battery life on full charge. As long as the odometer on the speedo works then that's good enough for me
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Re: Speedo Reading

Postby rossclark » Wed Oct 17, 2018 8:35 pm

burnside wrote:
shane BBoys wrote:Mine does something V similar I always use my phone speedo app, then at least i get a true reading, always have a battery pack pack up on trip over 2 hours though.

Shane.


That's where my Garmin Forerunner 201 comes in handy, GPS speed with distance, time, max speed, etc. and a 14 hour battery life on full charge. As long as the odometer on the speedo works then that's good enough for me


Same place, my odometer works (in km) and I have a 205 strapped round my headset.
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