Possible to adjust the speedometer?

[4strokeluvr111]

Just saw another post on TY where a rider ground teeth off of the gear by the speedo pickup. My 2005 Vector's speedo is consistently 10% fast (verified by GPS).

Is there a way to "fix" this?

Thanks!!!

 

[FAMILYMAN]

Yes removing a tooth at a time. Typically two teeth gets it pretty close.

 

[4strokeluvr111]

Yes removing a tooth at a time. Typically two teeth gets it pretty close.

Thanks! NOS-PRO PM'd me the same info!

 

[polarisconvert]

One is not enough, two is too much

 

[4strokeluvr111]

One is not enough, two is too much

I did two. We'll see what happens.

 

[tomanytoyz]

Wonder if anyone ground half a tooth? if nothing grind it all the way ! i left mine stock i dont care ...

 

[SounderMN]

I like thinking I'm faster than I actually am. What's wrong with that?

 

[Blue Dave]

Wonder if anyone ground half a tooth? if nothing grind it all the way ! i left mine stock i dont care ...

A half tooth will either register as a whole tooth or no tooth depending if the sensor "sees" it or not. The sensor "counts" the teeth that pass by it during a given time interval and that calculates into track speed. The sled computer is programmed with the number of teeth on the "gear". My Apex has 15 teeth on the "gear". When 15 teeth pass by the sensor it knows that the drive axle has completed one revolution. The distance that the track travels with one revolution of the drive axle is also put into the programming and that is how the computer translates "teeth per hour" (or per minute or second) into MPH.

When you remove teeth you "trick" the system because it is now taking slightly more than one revolution of the drive axle for 15 teeth to pass by the sensor. This results in the computer thinking that the drive axle is turning at a lower RPM than it actually is. You can get the same effect by changing the diameter or pitch of the drivers on the drive axle which changes the other part of the equation which is the distance that the track travels with one revoluition of the drive axle.

With 15 teeth on the "gear", removing one tooth will result in a 6.67% reduction (correction) in the indicated speed. Removing two teeth results in a 13.33% reduction (correction) in the indicated speed. Most Apex speedo's are off about 10% which is why one tooth is not enough and two teeth is too much. If you do remove two teeth do not remove adjacent teeth but rather one on each side of the gear (180 degrees apart) for a smoother signal from the sensor.

Interestingly they programmed the speedometer with this error but they programmed the odometer to be accurate. My odometer is right on the nuts but my speedo is about 10% fast. Therefore if you remove teeth to correct the speedometer error you will be creating the same amount of odometer error. This really proves to me that Yamaha did this by design to make people think the sleds are faster than they really are.

 

[4strokeluvr111]

Ground off two teeth and it's right on now at all speeds up to 70 mph (as fast as I went last night). Thanks to all that helped!!! Wish I would have done this long ago!!!

But my ODO will be showing the correct mileage? Iguess I assumed that if my speedo was 10% off the ODO would be the same.

 

[Blue Dave]

Did you take off two teeth on opposite sides? If the speedo is nuts on now you were off by about 13% as I explained above. Check your odometer now as I bet you will find that it reads low since it was most likely accurate with all 15 teeth on the "gear".

 

[4strokeluvr111]

Did you take off two teeth on opposite sides? If the speedo is nuts on now you were off by about 13% as I explained above. Check your odometer now as I bet you will find that it reads low since it was most likely accurate with all 15 teeth on the "gear".

10-4 on the opposite teeth. If the ODO is low that's OK. If/when I sell the sled I will disclose it....I have nothing to hide!