‘74 450 Desmo speedo & tacho

[IanHood]

Does anyone here know which speedo and tacho would be correct for my UK ‘74 450 Desmo - CEV or Smiths and would the speedo be in mph or kph. I’m guessing it should probably be Smiths gauges and in mph (in which case it’s going to be a nightmare to find them).

Ian

[themoudie]

Aye Ian,

My '74 MKIII 450 came with Smiths instruments and with 'MPH' graduations. The rev counter needle stopped twitching after a wee while, even though the cable and drive are all connected and smooth running. Whilst the speedo needle twitched and wavered and then finally succumbed after ~35K, inspite of a well lubricated cable and helical drive, both freely spinning. The needle failing before the mileometer.

Because of the obscene prices, if they can be found, and their unreliability, either to function or display actual MPH or RPM, my old instruments sit in a drawer and I have fitted an Acewell universal instrument binnacle that gives an accurate MPH reading and reasonable RPM reading as a moving bar chart. Alternatively, you could fit a pair of the cheap analogue instruments that are readily available, but their reliability and accuracy could be questionable.

If you are going to ride the bike I would'nt bother with OME instruments. If you have the binnacle, hang on to it and maybe use a cheap pair of analogue instruments, if "style" matters.

Good health, Bill

[IanHood]

Thanks Bill, that confirms my suspicions and I suspect I will go with cheap analogue instruments in the original binnacle. At least it will look right, even if the accuracy is questionable…

Ian

[blethermaskite]

My UK model 350mk3 came with kph smiths speedo and matched rev counter.......they were both complete rubbish! the speedo failed before I had the bike run in and the rev counter failed after about six months. I am using a 1960s smiths black face race rev counter which has worked faultlessly for over 40 years, I am now on about the sixth speedo head after trying all sorts which have failed, now trying a matching black face 100mph 1960s smiths speedo head which has been fine for a couple of years now ( I believe its from a BSA b40?).
Cheers,
George

[Jordan]

I think needle "twitchiness" could be caused by too much free play in the geared spindle of the drive gearbox.
That could make for unsteady rotation as it moves lengthways under influence of the helical gear mesh?

The better quality Contagiri per Competitzione gauge has a larger dial but the body has the same diameter as the smaller cheaper gauges.
When I had a single with the black rubber gauge housing, the bigger tacho was used - looked nice and sporty next to the small "Vague-liar" speedo.