Speedo accuracy adjustment? - Lm

The speedometer on my Le Mans is reading 12mph to 15 mph optimistically throughout the speed range. I know this because I have checked it against my sat nav after realising that all of the cars on the road weren’t doing 75 mph on the A61!
I have had a look and cannot see that there is any way for me to “adjust” the accuracy…unless somebody on here can tell me differently?

Does anybody have any recommendations who might do a speedo refurbishment?

My S3 shows 20mph while in the shed at a standstill, and yes to be honest, I never really know what speed I’m going, but hey, I don’t commute on it so it doesn’t bother me. They can be rebuilt but the bezel is a pain to remove and put back without damaging it, good thread here: Veglia repairs

I’ve heard this chap is good :Speedo repairs

Bike Mag clocked up about 140 down the track on one of these in 1977, unfortunately it only worked out at 132 on the test equipment. Still enough to claim the fastest bike on the road at the time and send sales for Guzzi through the roof.No way to adjust them as far as I am aware

I have done this by taking speedo out of its case, which means prising off or cutting the black band around the face; once accessible then needle can be rotated on its shaft as it’s only a press on fit. Need to mark the magnetically driven dish thingy at the back relative to the frame (two marks then, aligned) to one position, say 50 mph for example, hold it securely in place with e.g. long nosed pliers then turn needle backward or forward by the desired amount. The fly in the ointment is inevitable damage to the rim clamp.

NB: 12 - 15 mph is within the required +/–10% I think for a 140 mph speedo?

Adam, thanks for the links. I don’t think I’m capable of taking off the bezel without serious butchery occurring.

Mike, yes I can see how that would work, but as I said I will probably butcher the bezel, and so I may contact the refurbishing chap and see if he can recalibrate.

a cheap fix is to fit a bicicle speedo you can get them from Halfords. I use one on my old cali its verey accurate it will record speed up to 120mph plus trip milage. and it only cost£9. make sure you get one that is hard whired( not whirless). don’t bother whith the expensive ones.

On e-bay for a few quid they are easy to calibrate and see. as Buzz ses don’t go for expensive one, or even a back it one as once you KNOW what speed is where you tend to mentally recalibrate the Guzzi speedo.

I know that the speedo at 80 is true 75-5 well within legal . at 30 it is a needle width over the 30 mark , 40 on the speedo is a true 45 and it goes real wierd at 50 and 0 then seems to even out .

Nice to KNOW the 30/40/60’s tho’ as that is where the nasty cameras are.

Reggie - if you do eventually get it sorted out by Peter Bond, I would be interested to know by PM how much it all works out at if you remember! Thanks…

I thought that’s why they are called vaguelia.I did 130 on my Mk1 on Sunday!?!?

No reason why that’s not possible on a Mk1 Le Mans with the help of a bit of tailwind. My Mk1 was very fast.italianmotor2013-07-10 17:19:19

WELL the 850 Le mans was often 140 new so not at all unusual

Adam wrote;Reggie - if you do eventually get it sorted out by Peter Bond, I would be interested to know by PM how much it all works out at if you remember! Thanks…

Yes I will if I do, but I may wait until the end of the riding season i.e. start of crap weather.
The speedo in question doesn’t have a trip meter on and so I may look for one of these instead, but haven’t decided yet.

My 1200 sport is miles out as well. I just made accurate marks ( taken from the sat nav ) with a black indelible marker on the outside of the speedo glass for 70 80and 100. At 30 it’s far enough out to worry

The push bike speedo i have has a miles/trip/time on road???/clock and the speedo can be set easily for MPH/Miles or KPH kms… easy to fit easy to set up and all well under £10 Set up info is on the “This old tractor” site

I can see it easily and it is left set in clock so looks ok too, Oh yeah easy to clip on and off the bike should you wish to. I did find out I can’t leave it on if the bike is sat outside in the rain , it does dry out ok and is ok in normal we running, but left outside for 3 days in a very wet Wales it took 3 hrs before the readings came back. Battery has lasted 2 yrs up to yet.