Speedo accuracy (mine seems on)

[The Big Red One]

Mine was off 7% at 100 mph....an indicated 100 was actually 93. and the error grows as the speeds increase ???

 

[HiYaBruceA]

I got a yellow box when I changed to 220 MPH speedo faceplate, and calibrated it by making repeated passes in front of a roadside speed indicator, which seem to be surprisingly consistent from place to place. Based on that I'm pretty sure my speedo reading is now accurate.

 

[KappaSigBusa]

how easy is it to dial the speedo in with a speedo healer (never used one) ???

 

[majestic12]

Mine seems spot on but every now and then I see a blue hair in a minivan pass me.
Not a problem mind you, But it does makes you wonder if you are going 80 like the speedo says.

I had a truck once where the speedo would have almost an exponital error. ie 35 was on but when you showed 70 you were acutaly doing 90. Man it made great time on a trip but I had to stop for gas often.

 

[apehog]

Mine seems spot on but every now and then I see a blue hair in a minivan pass me.
Not a problem mind you, But it does makes you wonder if you are going 80 like the speedo says.

I had a truck once where the speedo would have almost an exponital error. ie 35 was on but when you showed 70 you were acutaly doing 90. Man it made great time on a trip but I had to stop for gas often.

 

[faster]

Not argueing that the speedos are off. I know mine was when I had it radar checked by a buddy.

Now on the drag strip comment. They dont give you an actual exit speed. You get a trap speed meaning your average speed through the trap at the end of the track. There is no radar at the track. So they look at your time from the light at the entrance to the trap and the light at the exit of the trap. Therefore giving you the trap speed. Trap speed will be lower than actual. The reason being, you enter the trap at apeed X and exit the trap at speed y. The time in the trap equals Z.

The only time your trap speed would match your actual would be if you were gear/hp bound prior to entering the trap.

I am well aware of how a speed trap works on a dragstrip. I am also aware that they are 66 feet long at the end of the run. At 150 mph it takes 3 tenths of a second to go 66 feet which is the same time it takes to blink your eye. So how much difference is there really on a stock Busa in the entrance and exit speed of a speed trap? How much speed is a stock Busa going to gain in 3 tenths of a second which is the blink of an eye? You would maybe gain 1 mph, if even that. STOCK BUSA.

What we are talking here is a minimum of a 12 mph speedometer error (mine was more) and this would make the 1 mph gain in speed speed through the traps inconsequential. In other words, you will see the difference in speed between what you see indicated and what the timing slip is showing.

Of course at full throttle acceleration it might be tough to coordinate all your thought processes and see all this as you are going through the traps. But......you could run the bike up to 100 mph steady speed and see very accurately what the speedometer error actually is.

Remember......we are talking basically stock bikes here, not a John Force funny car.

 

[oldschool]

how easy is it to dial the speedo in with a speedo healer (never used one) ???

Very easy, especially if you have a GPS that can recall your top speed (the speedohealer also has a top speed recall feature). Just go on a ride and when you get back recall the top speed on the GPS and on the speedohealer then put that info in the speedohealer website and it will give you step by step instructions on which buttons to press. If not then just remember the offset like an indicated 70mph was 64mph on the GPS or whatever yours is reading.

 

[KappaSigBusa]

thanks oldschool