KMH to MPH conversion

[Paul]

My FJ is an Italian import and only shows KMH on the speedo - does anyone know where I can get an MPH overlay?   Alternatively I have seen converters available that seem to fit in-line between the speedo drive and the speedo - does anyone know if these are any good, and which one to order (The options seem to be top or bottom of speedo cable, and mechanical or electronic).

My FJ also seems to read quite optimistic on the speedo - is this common?

[Hepcat]

I have a converter fitted to the top, was on the bike when I bought it. Seems to work okay, took me a couple of days to realise it was on kept saying this seems fast for 50mph when speedo was reading 80Kph

[jwh]

i used to have a gsxr 750 with kph clocks, came with an overlay on top of them, which was crap, so go a mechanical converter, it was a small blue aluminium device that went on top of cable and screwed into the clocks, and it was spot on, it just geared the clocks differently so 80kph became 80mph etc, checked it against other speedos and it was very accurate, i think it was about £20 from a bike shop (they came in 2 colours, blue ones went at the clocks end of cable and pink ones went wheel end). have never tried an electronic one.

[Paul]

Thanks guys - I'll go with the mechanical converter.   Looks like they're about £40 from M&P accessories, although I'll look see if I can find one cheaper.

[Flying Scotsman]

How about geting a GPS then you would know actual speed.My speedometer is off about 6 or 7 mph

[andyb]

Or get a set of ebay gauges, preferrably broken, and tear them apart and swap stuff around.

[jwh]

i think i got mine from m&p but they must have gone up in price (was a few years back!) if they are that much try asking audibeck on ebay
(am assuming you are in uk if you are looking at m&p) he normally has a few clocks in, and probably wont charge that much for a set of uk ones.

[Paul]

I've tried calibrating via a SatNav's GPS and also a local electronic speed warning sign (Just for safety, honestly officer) and the speedo seems to be way off at lower speeds, but more accurate at higher speeds.   Checked with my mate and he reckons his FJ reads at least 10% over.   I did consider getting some UK clocks but will I need to make any other mods or is that all that's required?

Thanks for the advice anyway guys.

[andyb]

Speedos aren't linearly innaccurate.  At least in my experience with mechanical ones.

What's 5% off at 50 might be 10% off at 100.  Or it could read slow at low speeds and high at faster speeds.  Tachs are guilty of the same crime. 


I want to say the clocks interchange throughout the years entirely for the 1200's.  If you take the assembly apart, you should be able to just swap over the speedo and keep the rest.  Best answer might be using a gps and calibrating it to what you've got, then making your own face to be dead on, but it'd be tricky to make it look OEM.  It'd be as good a time as any if you were going to swap the lot over and make them all custom, though.

[Dan Filetti]

Speedos aren't linearly innaccurate.  At least in my experience with mechanical ones.

Best answer might be using a gps and calibrating it to what you've got, then making your own face to be dead on...

So this begs the question: why didn't the manufacturers do this from the git-go?  Maybe because they're all conspiring to stroke our ego's?

Food for thought.

Dan

[Arnie]

Dan Filleti said, "Maybe because they're all conspiring to stroke our ego's?"

That's probably part of the reason.  The other part would be to try and "save" us from ourselves.

IE, "Hey! Speedo goes to 180mph (290kph) , lets see if we can get the needle past that."

Arnie

[Dan Filetti]

Arnie-

You have more faith in people than I do.

Dan

[Kopfjaeger]

km/h to m/h   multiply km by 0.6214 miles / hour to kilometres per hour multiply miles by 1.6093.. had to be cheeky.... courtesy of engineers black book 2nd edition.

[Paul]

km/h to m/h   multiply km by 0.6214 miles / hour to kilometres per hour multiply miles by 1.6093.. had to be cheeky.... courtesy of engineers black book 2nd edition.

:-)   Yeah, I've been multiplying by about 1.5 to get a rough MPH figure on the move, but when I run past the speed trap I have to get 60KMH up to get a reading of 30MPH on the trap.   Took my mate Al to collect his FJ last weekend and following me on the way back he thought he'd get a ticket on the M25 because his (MPH) speedo showed 95 when both the speedo in my car and the SatNav showed 70 bang on.