Speedometer error

[haya:)boosta]

OK... I know the speedo is off to some degree, but at top end by how much? And, also, I just went down 1 tooth on the front sprocket...would that effect the reading in anyway? (BTW - I just buried the speedo for the 1'st time @ 185mph... and was wondering what was the true speed?) Thanks...and yes I tried a search first.

 

[BigBSBusa]

7-10%.

 

[haya:)boosta]

Thanks...

 

[NightCrawler]

185 on speedo is roughly 172 actual.

 

[haya:)boosta]

what about the sprocket change? any effect? my guess would be no.

 

[NightCrawler]

(hayaboosta @ Apr. 04 2007,16:53) what about the sprocket change? any effect? my guess would be no.

Big change.

Shortening the gearing (bigger rear and/or smaller front) will give you a higher than actual reading.

Lengthening the gearing (smaller rear and/or bigger front) will give you a lower than actual reading.

I read somewhere that placing a 18T up front will make the speedo accurate. I'm not sure if that's true though.

 

[dmrowe]

Good stuff already posted. You need a speedohealer of yellow box to correct for any changes in sprockets or tire sizes.

 

[dadofthree]

Mine was 7%

 

[DaCol.]

Mine

, 7% below 85-90 mph. Above that they are really off, but why are you looking at the speedometer going that fast  

. Better look at your tach the compute it with the gear ratio, sprocket change, wheel size etc. to get an accurate speed  

 

[Commuta_Busa]

ziptie a gps and you'll only be off by 1-2mph at the very top... (refresh rate).

tire size and sprockets are what effect your speedo. You can always run the mile markers and then compute how far off your speedo is. As your tires wear or the pressure changes also realize things will be skeewed.

 

[hydrabusa]

(DaCol. @ Apr. 04 2007,16:07) Mine

, 7% below 85-90 mph. Above that they are really off, but why are you looking at the speedometer going that fast  

. Better look at your tach the compute it with the gear ratio, sprocket change, wheel size etc. to get an accurate speed  

I'm thinking this is the right answer, here...

 

[dadofthree]

Pegged

 

[dadofthree]

178 GPS 190 speedo

6.4%

Not exactly accurate, but with radar at 70 speedo it was 7%

 

[proud dad]

Mine was 5.3% off at 60mph.Actually moving 57mph.Went 2 up on the rear.Now its 10 +%reads 60mph,now running 54mph.reads 100 only doin 90mph.I gotta get a speedohealer.

 

[NightCrawler]

(dadofthree @ Apr. 05 2007,20:44) Pegged

You pegged the speedo. Try pegging the tachometer ...  

Your speedo stopped at 185 but I'm sure your tach was still climbing, meaning you were still gaining speed.

10,200 - 10,500 rpm otta do.

This was stock but I had to let off due to what were once itty bitty cars becoming much larger.

 

[hydrabusa]

So, in general...7% is about right, if you go faster off more, slower for less...guess I need yellow box for my Banzaii...

 

[jjmetheny]

(hydrabusa @ Apr. 07 2007,05:04) So, in general...7% is about right, if you go faster off more, slower for less...guess I need yellow box for my Banzaii...

For stock gearing it's close.

 

[dadofthree]

I would hate to pay the money to run at Maxton, but I'm very limited on safe places to run. I do have one option I need to check out some time. Don't know if I can run 181. 250 lbs. + weight of gear, not to mention aero problems. Good run.

 

[Dr. Matt]

I asked a similar question as I'm trying set my speedohealer correction factor.  For those of you wondering, you can calculate %change due to gearing and tire size/wear from here: .  BTW  I just purchased another speedohealer for the best price yet $95 to include Priority shipping.(I've put them on all past bikes... great product)  http://stores.ebay.com/HILLS-SPECIALTIES-HAYABUSA-PARTS  As you will see, Josh has other Busa parts as well.