Speedo accuracy

[pinholenz]

Greetings from NZ. I suspect my speedo might be well out of range. Standard tyres on the xz550, 5k on the tacho in top gear and she's reading 80kph on the speedo. I'd appreciate some comparative speed readings from other bikes at 5k on the tacho please. Cheers.

[Rikugun]

A test I read claimed 5295 RPM at 60 MPH/97KPH.

[Rick G]

Its somewhere close to 11 mph per 1000 rpm.

[iain]

Mine was out heaps when I got it,,  wouldnt read over about 130 km

Iain
NZ

[supervision]

  With a 90/90 front and 110/90 rear mine is 5,000 at 55

[Tiger]

  With a 90/90 front and 110/90 rear mine is 5,000 at 55

...multiply by 1.6 = 88 K P H ;)

[pullshocks]

I rode by one of the "Your speed is" radar units today.  It said I was going 29.  The speedo said 37.  Pretty far off.

[supervision]

   Oh my speedometer @55mph your in the red zone till 80mph, where nothing indicated beyond 80mph.   My bike will go just fine up their, I can pull redline, 10,000rpm, in fifth!!!   What's up with that?  The person who made the speedometer must have never rode one, or they would have surley known the bike can go much past 80mph. 

[Lucky]

that is assuming the radar machine was accurate..
think of it as a ticket avoidance calibration..  "but Officer, my speedo isn't accurate.."  :)

[Rick G]

The 82 speedo (and all speedo's of that era) won't read past  85.
The woman in charge of the US transportation dept, Joan Clayburg, felt that if you did not know how fast you were going, you would not speed. Ya sure.!!

[fret not]

She also tried to get seat belts required for motorcycles!!!! :o ::) :police:

[Rick G]

Have you seen the front wheel drive one, she had created?  No one could ride the damd thing!

[supervision]

  those jive agencys, need to be discouraged, out of exisiatance.   IMHO

[don_vanecek]

I have been told by other riders that my 55 is their 60, my 60 is there 65 (mph that is). Like many of us I have moved to a 100 size tire up front, one size up from the original 90/90, frankly I would rather have it the other way around (my 60 their 55).

Anyway, that's what other guys have told me, so far I haven't had to discuss with an officer. 

[pinholenz]

Many thanks to you all. By my reckoning and your experience (assuming the tacho is accurate of course) and with standard tyres, at 100 kph my tacho should read 5484 rpm.Therefore if my Tacho at 5000 reads 80kph, I am actually doing 92kph. Or if my speedo is showing 100kph (the legal motorway limit in NZ) I am probably doing about 114kph. - enough to attract the  :police:. Hmm. Quite a way out. I did think I was going faster than what the instruments were telling me.  Cheers.

[dpequip]

One thing to remember here, is that USA market and other world market bikes will have different primary drive gear ratios.  This will affect the RPM vs indicated speed ratios.  The USA gear set gives more RPMs for a given speed.  Supposedly this was done to produce better 1/4 mile times during magazine tests in the USA?   If I remember correctly the gearing difference was about 10%.  I put a euro ratio primary gear set in my USA spec Vision  back in 1984 when you could still order these parts new.  Took about 3 months to get as Yamaha had to ship the parts from Japan.  Lowered the revs on the highway and made 3rd gear perfect for riding curvy roads.  It was one of the best changes I made to my Vision over the years.

[Rikugun]

I would think that no matter the intended market the bike would be shipped with a reasonably accurate speedo. Could there be different drive units and/or speedo inner working to match the gearing used for each market?   

Maybe inaccuracies can be attributed to age as well as in some cases where parts have been mixed and matched. Is it possible the spinning magnet loses some strength over time or the needle's axle gets sluggish from old gummy factory lube? Just a thought...   :)

[Rick G]

The 82 speedo's are just crap. All other countries used the same KPH speedo , which seems to be a better instrument.

[lexx790]

I've tested my speedo against a sat nav and found it to be reading 10% fast, so at 70MPH it reads 77.
I had thought about correcting it, as it is only the spiral spring tension against the magnetic drag on the needle.
When the speedo is out next I'll set the speedo running with an electric drill turning it at a constant speed then re-tension the spring to reduce the reading by 10%.
Well it seems good in theory  ::)