Speedometer Error
07-17-2010 | 10:37 AM
#31
Out of my mind, back in 5
MotoGP
Joined: Nov 2006
Posts: 6,109
From: Skurup, Sweden
I've always wondered if there is some kind of electrical voltage fluctuation. I know that my bike is fairly stable (because of the modified ground wiring from the charging system) but it will still vary quite a bit. Each recording was made a the same engine speed (4000rpm) but it's possible that for some reason the voltage was different each time. Since my assumption is that the speedometer is a cheap device, it would stand to reason that it doesn't compensate very well to changes in chassis voltage. Not sure, just another theory.
But yeah, bad grounding, or different grounding resistance in different parts of the bike will definetly throw the measurements off... Another good reason to do maintainance on your bikes electronics as well as mechanic parts...
07-17-2010 | 11:05 AM
#32
Banned
MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
Well I guess I'm going to need to do some testing when I get the bike back on the road.... This has been an interesting read so far and I always thought my speedo read a pretty consistent 10% fast with my gearing but I never really paid too much attention to it. 
07-17-2010 | 12:56 PM
#33
Senior Member
Superstock
Superstock
Joined: Apr 2007
Posts: 293
It's been awhile since I've done a highway trip long enough to worry about it (last summer), but with 15/43 I think it's darn near 15mph off. So 80 indicated is about 65. I will be taking a 1500-2000 mi trip in Sept. I usually run a GPS program by google called "mytracks" that I can then pull the .gpx files into google earth for later use. It's nice, as you can see what your exact speed was on a specific corner etc, etc... But I digress. I will figure out exactly how accurate the odometer remains vs how far the speedo is off, cause I certainly don't want to put a speedohealer on if its throwing my odometer off drastically. I've been living with the speedo being off for a few years anyway. With the android os phone app "Speedometer" I can get it to display in huge numbers on the phone, that are far easier to discern than than the guage anyway. I'll let ya'll know what I find.
07-18-2010 | 08:07 PM
#34
jet wrench
Back Marker
Joined: Jun 2007
Posts: 175
From: cowtown, CA
It's been awhile since I've done a highway trip long enough to worry about it (last summer), but with 15/43 I think it's darn near 15mph off. So 80 indicated is about 65. I will be taking a 1500-2000 mi trip in Sept. I usually run a GPS program by google called "mytracks" that I can then pull the .gpx files into google earth for later use. It's nice, as you can see what your exact speed was on a specific corner etc, etc... But I digress. I will figure out exactly how accurate the odometer remains vs how far the speedo is off, cause I certainly don't want to put a speedohealer on if its throwing my odometer off drastically. I've been living with the speedo being off for a few years anyway. With the android os phone app "Speedometer" I can get it to display in huge numbers on the phone, that are far easier to discern than than the guage anyway. I'll let ya'll know what I find.
07-18-2010 | 09:29 PM
#35
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MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
That is true but what I meant was it has seemed to be consistent (by checking against local radar speed zones) at pretty much all speeds. I will have to pay a bit more attention to see if it varies at different speeds and gears.
07-18-2010 | 10:02 PM
#37
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Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
07-19-2010 | 09:14 AM
#38
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MotoGP
Joined: Apr 2006
Posts: 4,402
From: Kempner, TX
07-19-2010 | 11:36 AM
#39
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Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
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