Yellow box and 220 guages

[rustman]

I would imagine this topic has been beaten to death, but the last time I looked, I didn't find a definative answer to the 220 guages and the yellow box. Here is what I've found:
The dyno shows my bike tops out at 177.2mph at 11K. Yes, it's dissappointing, but I believe it's true, rather than believe the hype. I have the yellow box set to be pretty much accurate at 40mph and it's pretty close at 70 as well as verified using a GPS. My speedo read 190mph at redline in sixth gear, and the dyno showed 177.2mph. This means that the speedo gets progressively optimistic as I get up into the triple digits. I just wanted to share my data. Anyone else had any experiences with this set up?

 

[Rosco]

Been wondering about speedo linearity myself. Maybe someone can help.

 

[BigBSBusa]

Only way to be completely sure is use a GPS.

 

[BA BUSA]

You need to check it with GPS....how accurate is dyno

 

[shenoyp]

I dunno how accurate a dyno is... but the most reliable way to find out would be a GPS IMO

 

[Pop]

http://www.speedohealer.com

 

[NearDeath]

The busa speedo is off... that is all there is to it.... It gets more off the faster you get... No matter how much you mess with the yellowbox/speedohealer, I don't think you are going to get it dead on because again it is off stock to begin with and gets worse with speed. Not sure how you are going to fix that one...

Cloud

 

[IL_BusaBoy]

Only way to be sure is GPS.

 

[jay21112]

I know next to nothing about how the yellow box works, but what I fathom is that:

The bike's speedo is off in an exponential manner and the yellow box attemps to fix it with a linear equation.

linear does not equal exponential, so it will only be accurate for part of the speedo "sweep".

Now if there was a yellow box with an exponential equation....

 

[GOD]

If it works the way i think it should be very simple. your speedo is always going to be off, not at a set mph(like 10 miles an hour), but a constant percent. so no matter how close it is, if it is off at all the number of miles it is off is only going to grow the faster it goes. 1% of 200 is a greater number than 1% of 100. The only thing you can do is get it as acurate as you can at the fastest speed that you can.

 

[rustman]

I know next to nothing about how the yellow box works, but what I fathom is that:

The bike's speedo is off in an exponential manner and the yellow box attemps to fix it with a linear equation.

linear does not equal exponential, so it will only be accurate for part of the speedo "sweep".

Now if there was a yellow box with an exponential equation....

Jay, you're exactly right.  The yellow box lets you enter a percent correction factor, whether it be plus or minus.  This means that you can "slide the scale" one way or the other but the increments between speed readings will remain linear.  I determined my correction factor using a GPS and going 40mph. (That's a speed that I could hold in the neighborhood.)  Dialing it in at a higher speed would be better.

The linear approach would probably work if the original guages were on (because the stepper motor in the guage is set to move a specific distance based on the pulse rate from the ECU and this distance is appropriate for the stock guages), but the speed markings on the 220 guages are closer together, so the readings will be off exponentially on EACH SIDE of the speed that is dialed in with the box.

This is what I believe to be true, but the names have been changes to protect the innocent...