Speedometer question on 1400

[Ncdan]

Comparing my speedometers to my GPS, the bike is 3MPH fast and when the bike showed 125 miles the actual mileage was 130. My question is can this be on board adjusted. Thanks in advance:)

[LowRyter]

Much more accurate than any of the speedometers on all three of my motorcycles.

[JohninVT]

That matches with my own observations.  It's actually the most accurate speedometer I've ever had on a motorcycle.  It's off 2-3mph at 65 and about 5mph at 90.  67-68 is 65 and 90 is 85.  3% is pretty darn good for a bike.

[Ncdan]

That's good to know that mine is like y'alls, so can I assume there is no on board  adjustments for the issue?

[Kiwi Dave]

Tyre diameter from new to worn will change the speedo accuracy too.  Perhaps Guzzi should have incorporated an automatic adjustment for this too?   

[Zoom Zoom]

That matches with my own observations.  It's actually the most accurate speedometer I've ever had on a motorcycle.  It's off 2-3mph at 65 and about 5mph at 90.  67-68 is 65 and 90 is 85.  3% is pretty darn good for a bike.

This /\

Although my odometer is within a few 1/10ths, (less than 1 mile), when comparing it to the GPS ovre a tank of fuel. (180 miles)

John Henry

[Moto]

The calibration for the wheel size must be in there somewhere.

Let's see, if you wore 1/4" of tread off of a wheel that had a radius of 13 inches, for example, that would be a change of (.25/13)x100 = 1.9, or roughly 2 percent. So the 3 percent you are concerned about, if corrected, could be thrown off substantially by tire wear. (Pulses per mile sent to the speedometer is proportional to tire circumference, which is proportional to diameter and radius.) Probably an even more important influence on the effective radius is tire inflation pressure.

I agree that the 3 percent error is negligible and that correcting it for your current tire diameter would be of little long term benefit.

But it would be fun to be able to do it. (I found out how to do it for my Italjet a while ago.)

Moto

[Ncdan]

The calibration for the wheel size must be in there somewhere.

Let's see, if you wore 1/4" of tread off of a wheel that had a radius of 13 inches, for example, that would be a change of (.25/13)x100 = 1.9, or roughly 2 percent. So the 3 percent you are concerned about, if corrected, could be thrown off substantially by tire wear. (Pulses per mile sent to the speedometer is proportional to tire circumference, which is proportional to diameter and radius.) Probably an even more important influence on the effective radius is tire inflation pressure.

I agree that the 3 percent error is negligible and that correcting it for your current tire diameter would be of little long term benefit.

But it would be fun to be able to do it. (I found out how to do it for my Italjet a while ago.)

Moto

Now thats an educated answer and a little over my mathematical skills but it sounded like you just said to leave it to hell alone it's ok. LOL, thanks for the response Moto. The 5 miles difference from 125 to an actual 130 miles will make quite a deference over several thousand miles.

[Moto]

... The 5 miles difference from 125 to an actual 130 miles will make quite a deference over several thousand miles.

No doubt. It must be frustrating for the engineers to admit that there is no practical way to get complete accuracy from tire revolutions. (GPS is a different matter.)

[TN Mark]

There's a device called a SpeedoHealer that's made to correct the speedometer error. The electronic item is sometimes used with belt drive bikes when they change to a smaller front pulley. In some cases, adding an underdrive front pulley may add a 7% error due to the front pulley smaller size. Here's a link to the device: https://www.healtech-electronics.com/products/sh/

But in your case NCDan, I'd leave things as they are.

[beetle]

Later model Guzzi's have a speedo correction factor in the map. For the CARC series, this value varied depending on whether the bike had ABS (dual sensors), or single front or rear speed sensor. For ABS bikes (including) the 1400 Cali, the ABS unit does the speed number crunching. The ECU crunches it some more, then sends the speed data to the dash via CAN bus.

I have not found (nor bothered to look, to be brutally honest) for any speed correction values in the map. It may not exist, given the Cali is not available without ABS, and the ECU may simply convert it to a format the dash requires. In that case, trying to change it may be impossible.

Given that the ABS unit is vital to the speed display, I would strongly advise against any attempt to modify it. Let's face it, a 3% error is pretty damn good.

[lucian]

Fortunately the error is > actual or we'd all be without a licence.

[JohninVT]

Fortunately the error is > actual or we'd all be without a licence.

I was curious so I tried setting the cruise control at 100mph.  Yup, you can set it at 100mph.  I’m pretty sure my license isn’t safe whether I’m riding the 1400 or a moped.   

[Moto]

Fortunately the error is > actual or we'd all be without a licence.

I believe speedometers are generally set to read high by the vehicle manufacturer to give it protection from liability for speeding tickets that might come from having them set low. They can't just calibrate them to the true speed for fear that uncontrolled factors would make some read low and some high. No evidence for this though, except my observation that they always read high.

Moto

[Ncdan]

I was curious so I tried setting the cruise control at 100mph.  Yup, you can set it at 100mph.  I�m pretty sure my license isn�t safe whether I�m riding the 1400 or a moped.   

John boy, you ain't right😂

[Ncdan]

Thanks guys for the schooling on the subject and yes 3 MPH reallys not much. I just figured with all this advanced technology some of you guys would know if there was a simple way to correct even a minor inconsistencies through the ECU. Thanks again!

[Kiwi Dave]

I have not found (nor bothered to look, to be brutally honest) for any speed correction values in the map. It may not exist,

I tried to tweak my Norge speedo a few years ago, but the speedo just went crazy and went full scale at walking pace.  Obviously, I must have got something wrong.  Luckily, I noted the original value.

[beetle]

The way to do it is to note the percentage difference between actual and indicated speed. Multiply the speedo correction value by the percentage difference, then reduce the correction value by the result.

I always reduced the correction value by about 95% of the difference, to be sure that indicated speed was less than actual. I didn't want people going faster than indicated. I've had to do it for the 1200 Sport quite a few times. The error on the front wheel sensor was often woeful.

[elvisboy77]

Moto Guzzis read in ITALIAN MILES.  Not the same as plain old miles.  Thus the difference......

[Ncdan]

The way to do it is to note the percentage difference between actual and indicated speed. Multiply the speedo correction value by the percentage difference, then reduce the correction value by the result.

I always reduced the correction value by about 95% of the difference, to be sure that indicated speed was less than actual. I didn't want people going faster than indicated. I've had to do it for the 1200 Sport quite a few times. The error on the front wheel sensor was often woeful.

So this is something that's done through the laptop connected to the
ECU if a bike is off considerably and fairly simple to make the adjustments?

[Kiwi Dave]

So this is something that's done through the laptop connected to the
ECU if a bike is off considerably and fairly simple to make the adjustments?

From what Beetle said, and my experience on my Norge, it ain't going to be that simple if the bike has ABS.  It was simple tweaking a non-ABS bike (like a 1200 Sport) but since the Cali 1400 has ABS you might not be successful.

My $0.02¢.

[Diploman]

All of these inaccuracies - speed, distance, tire size, gearing, etc - are moot with a GPS speedometer.
Spot-on accurate readouts for speed and distance, and the GPS speedo is totally indifferent to changes of wheel or tire size.  Additionally, the weight, unreliability and general hassle of cables and drives is completely absent.  This is an easy, worthwhile modernization.

[Kiwi Dave]

All of these inaccuracies - speed, distance, tire size, gearing, etc - are moot with a GPS speedometer.

Until you're riding in a long tunnel.

[beetle]

So this is something that's done through the laptop connected to the
ECU if a bike is off considerably and fairly simple to make the adjustments?

Not exactly. The the map has to be modified, then reloaded. As I previously mentioned, I don't know if the Cali map has this feature. I've not tried to find it in the map.

[lucian]

I wonder if the calibration function for the TC and ABS is also responsible for keeping the speed correction within design parameters ?

[Ncdan]

I can live with with a reading of 60 MPH when actually running 57 that may save me a citation sometime and also it's easy to calculate total mileage over a period of time, the odometer showed 125 and the GPS WAS ACTUALLY 130. So instead of the odometer reading getting 40MPG I actually got 42 mpg:) Im just trying to increase my overall knowledge of how this modern beast thinks!