Speedo/Odom Experiment - Part 2 - Wrist Twisters
 
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post #1 of 11 Old 09-19-2008, 06:22 AM Thread Starter
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Speedo/Odom Experiment - Part 2

So I strapped a different GPs to my stock 04 919, and again it showed the same exact error as last time on the speedometer. Subtract 10% from indicated to find the true speed. This error was constant for the whole range of speed (tested from 35 - 100).

As for the odometer, the odometer showed 55.5 miles after the trip, and the trip meter on the GPS indicated 54.3. Also considering that the GPS stopped tracking at least once on the trip for less than a minute, the odometer error is less than 2.4%.

I find it a little odd that there is such a difference in errors between the two instruments. I'm going to do a clear sky trip to recalc the odometer with no interuptions to get a better idea of the error. I have a feeling its much closer to 0 than 2.4%.

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post #2 of 11 Old 09-19-2008, 06:33 AM
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10% seems like a universal standard. My KLR is optimistic by that. My zx10r was 8%. I used stationary radar at two different locations for the test. No info on the odo though.

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post #3 of 11 Old 09-19-2008, 07:14 AM
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what is the (+ -) on the speedo? been bugging the pi$$ outta me





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post #4 of 11 Old 09-19-2008, 10:09 AM
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I tested this theory myself just today too. I was considering a speedo healer when I read on their own site that if I were to install it, my odometer would now likely be off! However I just used google maps to get a mileage estimate, I followed the course exactly and 32.2 miles later they matched up exactly. My GPS also claims my speedometer is off by just about 10%.

Making the speedo read high is a retarded way to try and make bikes more safe.. now I find myself just gonig as fast as I want, I'm tired of doing math while im driving!

side note: I'm considering make up a new overlay for my speedometer to fix my problem.. anyone ever do that? I've seen people do it alot for car gauges (though not to corret discrepencies, heh) .. I guess the gauge would look a little weird not being totally uniform but it could work and would be cheap :P

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post #5 of 11 Old 09-19-2008, 10:14 AM
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I've checked my odometer twice against a gps on two 60-70 miles little jaunts around.

Both times they were around .2 tenths different in that distance.

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post #6 of 11 Old 09-19-2008, 03:36 PM
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On my 07 919 the speedo seems to be off about 10% compared to my GPS. I checked my odo on a 150 mile trip and it was off about 2%

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post #7 of 11 Old 09-19-2008, 04:38 PM
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Checking your odo against a GPS works in theory, but it won't take into account lines that you will choose to ride or hills that you go up or down. How many miles up are those satillites? Up here in Canada AAA marks out sections of highway on straight flat ground (5 Kms). I have checked my odo with a 15, 16, and 17 tooth sprocket. 16 is out about 10%, 15 tooth is out even more. 17 however, right on. As you may guess, the speedo follows the odo. With the different sprockets, same bike, same section of road, same rider. I'll let you draw you own conclusion.....

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post #8 of 11 Old 09-19-2008, 05:40 PM
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Quote:
Originally Posted by rickard919 View Post
Checking your odo against a GPS works in theory, but it won't take into account lines that you will choose to ride or hills that you go up or down. How many miles up are those satillites? Up here in Canada AAA marks out sections of highway on straight flat ground (5 Kms). I have checked my odo with a 15, 16, and 17 tooth sprocket. 16 is out about 10%, 15 tooth is out even more. 17 however, right on. As you may guess, the speedo follows the odo. With the different sprockets, same bike, same section of road, same rider. I'll let you draw you own conclusion.....
Yep. But I've done straight sections of interstate. Both by mile markers and GPS my speedo is 8 miles an hour high, mileage dead on, with two GPS I own.

I've also checked one Chevy and two Fords I have. They're dead on both speed and odo.

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post #9 of 11 Old 09-19-2008, 07:23 PM
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Honda Jim, try changing your front sprocket if you have a different one and try again with the gps. I am curious what it will do. I have checked my truck with my gps and seems to be right on, bike is out. Each bike different? You have a speedo healer?

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post #10 of 11 Old 09-19-2008, 07:56 PM
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Quote:
Originally Posted by rickard919 View Post
Honda Jim, try changing your front sprocket if you have a different one and try again with the gps. I am curious what it will do. I have checked my truck with my gps and seems to be right on, bike is out. Each bike different? You have a speedo healer?
All my bikes are stock gearing and tire sizes. No speedo healers. No other sprocket sizes to try.

The 9er, Superhawk and F3 all are the same as far as odo on and speedo off. Never checked the Hurricane.

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post #11 of 11 Old 09-19-2008, 09:18 PM
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Both my gal and I ride 9ers. I have on a 16/45, hers I put on 17/43. Her speedo and odo is right. My speedo is out (10%) and odo always reads that I have gone about 10% farther than she has gone. Same size tires front and rear. Rear sprocket have an effect?

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