13 replies to this topic

[Russ528]

So, 4th gear - what's your speed at 3000 and 4000 rpm?

Just curious to see if my newly installed bike speedo is reading Ok on the way home later.

Cheers

Russ

[napala turki]

3000 rpm, approx 80 kph...
4000 rpm, approx 100 kph....

[Guess-Works.com]

It all depends on wheels size, Final drive ratio, speedo TPM, and the speedo take off ratio in the gearbox...

With those pieces of information ( or atleats the FD ratio and tyre size ) the speed @ rpm can be calculated. There's a calculator on my website

[cowboy]

3000 rpm around 60mph
4000 rpm speeding LOL 80mph

[rozzer!]

3000 rpm around 60mph
4000 rpm speeding LOL 80mph

i am roughly the same. dont have a speedo atm so use the rev counter instead!

[biggav]

So, 4th gear - what's your speed at 3000 and 4000 rpm?

Just curious to see if my newly installed bike speedo is reading Ok on the way home later.

Cheers

Russ

borrow a sat nav off someone and go for a drive. most sat navs do continuous speed/distance/time calculations and will give a very accurate speed reading for you to compare.

[Russ528]

It all depends on wheels size, Final drive ratio, speedo TPM, and the speedo take off ratio in the gearbox...

With those pieces of information ( or atleats the FD ratio and tyre size ) the speed @ rpm can be calculated. There's a calculator on my website

Ok, 165/60/12 tyres, assumed 3.44 FD, Metro 1ltr stuff...

3000 rpm = 51mph
4000 rpm = 68mph

Which is about what it was reading this morning, I believe.

Which is the same as Napali as well.

Yeah, I've got a TomTom, which I've used before - but I'd have to find the nearest motorway to use it on, as aroudn town, it can't vary it's speed reading quick enough to be accurate.

@ Cowboy - 4000rpm = 80mph? I said standard 998cc!

Edited by Russ528, 27 June 2007 - 07:14 AM.

[edjohnson]

my standard 998 does the same

3000rpm 60mph
3500rpm 70mph
4000rpm 80mph

speedo seems accurate when compared with sat nav

dunno what mini it came out of, all i know it was an 80's mini that got front ended

any idea what diff its got? and what mini it could be out of

standard twelve inch rover mini lites, with 145/70/12 tyres

[annodomini2]

One suggestion once you have it calibrated, set it to slightly over-read by a couple of mph, as your speedo can over-read by upto 10mph. But never under-read (MOT thing! )

[Russ528]

The original speedo is buggered.

I've read pretty much everywhere on this forum that a working speedo is not an MOT requirement?

[Guess-Works.com]

The original speedo is buggered.

I've read pretty much everywhere on this forum that a working speedo is not an MOT requirement?

Correct, it's not part of the MOT check, however it is a Legal Requirement....

Same as Wheels sticking out from the arches..

Placement of fog light

and plenty of other things... too inconsequential to mention.

[dklawson]

Russ528, if I neglected to share this information with you previously, I apologize.

When calibrating the bike speedo, get the calibration close like you have done by entering whatever calibration factor you mathematically determine. Once programmed, take the car to a place with a known, measured distance. Over here, certain stretches of road have measured mile markers. Set the bike speedo to "trip" mode and zero the trip odometer. Drive through the measured distance and come to a stop. Compare the trip meter's display to the known distance. Create a ratio of the two distances and multiply the original calibration factor by this ratio as appropriate to arrive at the corrected calibration factor. Enter this new calibration number in the bike computer and drive back over the same measured distance back to where you started from and repeat your calculations. If necessary (which it probably won't be) make any minor tweaks up or down. This will match your exact tire size (as it's rolling) to the speedo. It's as accurate as the measured mile markers you use.

[*DJH*]

1000cc 1987 tuned.
3000rpm - 60
4000rpm - 70
5000rpm - 82
6000rpm - 95
6500rpm - 106 Max speed.

[AshDeadman]

3000 rpm 75 mph
4000 rpm 90 mph